MF研究者総覧

研究者データベース

詳細
佐藤　友徳(サトウ　トモノリ)
地球環境科学研究院　統合環境科学部門　自然環境保全分野
准教授
researchmap個人ページ
Last Updated :2024/05/09

基本情報

所属

  • 地球環境科学研究院　統合環境科学部門　自然環境保全分野

職名

  • 准教授

学位

  • 博士（理学）（筑波大学）

ホームページURL

科研費研究者番号

  • 10512270

ORCID ID

J-Global ID

研究キーワード

  • 大気-陸面相互作用   ダウンスケーリング   気候変動   気候学   気象学   

研究分野

  • 自然科学一般 / 地球人間圏科学
  • 環境・農学 / 環境動態解析
  • 自然科学一般 / 大気水圏科学

担当教育組織

職歴

  • 2018年07月 - 現在 国立研究開発法人 防災科学技術研究所 客員研究員
  • 2015年04月 - 現在 北海道大学 北極域研究センター 兼務
  • 2013年01月 - 現在 北海道大学 大学院地球環境科学研究院 准教授
  • 2009年04月 - 2012年12月 北海道大学 大学院地球環境科学研究院 特任助教
  • 2010年03月 - 2010年06月 カリフォルニア大学ロサンゼルス校 客員研究員
  • 2007年 - 2009年 東京大学気候システム研究センター 特任助教
  • 2006年 - 2007年 東京大学気候システム研究センター 日本学術振興会特別研究員
  • 2006年 - 2007年 Postdoctoral Fellowships of Japan Society for the Promotion of Science
  • 2002年 - 2006年 科学技術振興機構 研究員
  • 2002年 - 2006年 Researcher

学歴

  •         - 2002年   筑波大学   地球科学研究科
  •         - 2002年   筑波大学
  •         - 1999年   筑波大学   第一学群
  •         - 1999年   筑波大学

所属学協会

  • 日本農業気象学会   日本雪氷学会   アメリカ地球物理連合   アメリカ気象学会   日本気象学会   

研究活動情報

論文

  • Hiroshi G. Takahashi, Shiori Sugimoto, Tomonori Sato
    Climate Dynamics 2024年01月20日 
    Abstract Influence of land-surface memory effects over the Tibetan Plateau on the Asian summer monsoon has long been studied, but not quantified because of the difficulty of extracting only these effects from observational data. This study examines the impact of spring land-surface conditions, including surface air temperature (SAT) and snow cover, over the Tibetan Plateau and its surrounding regions on the early stage of the Asian summer monsoon using large-ensemble experiments produced by an atmospheric global climate model (AGCM). The results show that the above-normal SAT over and around the Tibetan Plateau in May can enhance June monsoon circulation without the sea surface temperature (SST) forcing. The physical mechanism behind this involves warmed surface air over the plateau enhancing the north–south SAT gradient, leading to strengthening the Asian summer monsoon circulation and precipitation. Inter-ensemble correlation analysis indicated that SAT warming over the plateau is clearly associated with upper-tropospheric anti-cyclonic circulation anomalies in May. Also, although winter land-surface signals do not persist until late spring, SAT anomalies in March tend to persist until May, explaining 10–20% of the total SAT variance in May. Interestingly, the spring SAT impacts on June monsoon circulations vary interannually, indicating that the contribution of the land–atmosphere (L–A) coupling process to interannual monsoon variability differs from year to year. Active L–A coupling years tend to coincide with cooler SSTs with anomalous low-level divergence and upper-level convergence over and around the Maritime continent, implying that SST forcing is associated with the L–A coupling strength. Specifically, in May of the developing stage of monsoon circulation, the weak Walker circulation over the equatorial and northern Indian Ocean and undeveloped monsoon circulation are suitable for the L–A coupling to influence the development of the monsoon circulation effectively. However, the well-known oceanic events, such as El Ni$${\widetilde{n } }$$o, are found to be less connected with the interannual L–A coupling variations.
  • Jianping Tang, Yongkang Xue, Mengyuan Long, Mengnan Ma, Xin-Zhong Liang, Shiori Sugimoto, Kun Yang, Zhenming Ji, Jinkyu Hong, Jeongwon Kim, Haoran Xu, Xu Zhou, Tomonori Sato, Hiroshi G. Takahashi, Shuyu Wang, Guiling Wang, Sin Chan Chou, Weidong Guo, Miao Yu, Xiaoduo Pan
    Climate Dynamics 2023年11月03日
  • Shixue Li, Tomonori Sato, Tetsu Nakamura, Wenkai Guo
    Nature Communications 14 1 2023年09月22日 [査読有り][通常論文]
     
    Abstract The responses of the East Asian summer monsoon (EASM) to the Indian summer monsoon (ISM) have been the subject of extensive investigation. Nevertheless, it remains uncertain whether the ISM can serve as a predictor for the EASM. Here, on the basis of both observations and a large-ensemble climate model experiment, we show that the subseasonal variability of abnormal diabatic heating over India enhances precipitation over central East China, the Korean Peninsula, and southern Japan in June. ISM heating triggers Rossby wave propagation along the subtropical jet, promoting southerly winds over East Asia. The southerly winds helps steer anomalous mid-tropospheric warm advection and lower-tropospheric moisture advection toward East Asia, providing conditions preferential for rainband formation. Cluster analysis shows that, depending on jet structures, ISM heating can serve as a trigger as well as a reinforcer of the rainband.
  • Yongkang Xue, Ismaila Diallo, Aaron A. Boone, Yang Zhang, Xubin Zeng, William K. M. Lau, J. David Neelin, Tandong Yao, Qi Tang, Tomonori Sato, Myung-Seo Koo, Frederic Vitar, Constantin Ardilouze, Subodh K. Saha, Stefano Materia, Zhaohui Lin, Yuhei Takaya, Jing Yang, Tetsu Nakamura, Xin Qi, Yi Qin, Paulo Nobre, Retish Senan, Hailan Wang, Hongliang Zhang, Mei Zhao, Hara Prasad Nayak, Yan Pan, Xiaoduo Pan, Jinming Feng, Chunxiang Shi, Shaocheng Xie, Michael A. Brunke, Qing Bao, Marcus Jorge Bottino, Tianyi Fan, Songyou Hong, Yanluan Lin, Daniele Peano, Yanling Zhan, Carlos R. Mechoso, Xuejuan Ren, Gianpaolo Balsamo, Sin Chan Chou, Patricia de Rosnay, Peter J. van Oevelen, Daniel Klocke, Michael Ek, Xin Li, Weidong Guo, Yuejian Zhu, Jianping Tang, Xin-Zhong Liang, Yun Qian, Ping Zhao
    Climate Dynamics 2023年08月08日 [査読有り]
     
    Abstract The prediction skill for precipitation anomalies in late spring and summer months—a significant component of extreme climate events—has remained stubbornly low for years. This paper presents a new idea that utilizes information on boreal spring land surface temperature/subsurface temperature (LST/SUBT) anomalies over the Tibetan Plateau (TP) to improve prediction of subsequent summer droughts/floods over several regions over the world, East Asia and North America in particular. The work was performed in the framework of the GEWEX/LS4P Phase I (LS4P-I) experiment, which focused on whether the TP LST/SUBT provides an additional source for subseasonal-to-seasonal (S2S) predictability. The summer 2003, when there were severe drought/flood over the southern/northern part of the Yangtze River basin, respectively, has been selected as the focus case. With the newly developed LST/SUBT initialization method, the observed surface temperature anomaly over the TP has been partially produced by the LS4P-I model ensemble mean, and 8 hotspot regions in the world were identified where June precipitation is significantly associated with anomalies of May TP land temperature. Consideration of the TP LST/SUBT effect has produced about 25–50% of observed precipitation anomalies in most hotspot regions. The multiple models have shown more consistency in the hotspot regions along the Tibetan Plateau-Rocky Mountain Circumglobal (TRC) wave train. The mechanisms for the LST/SUBT effect on the 2003 drought over the southern part of the Yangtze River Basin are discussed. For comparison, the global SST effect has also been tested and 6 regions with significant SST effects were identified in the 2003 case, explaining about 25–50% of precipitation anomalies over most of these regions. This study suggests that the TP LST/SUBT effect is a first-order source of S2S precipitation predictability, and hence it is comparable to that of the SST effect. With the completion of the LS4P-I, the LS4P-II has been launched and the LS4P-II protocol is briefly presented.
  • K. Tamura, T. Sato
    Geophysical Research Letters 50 11 2023年06月06日 [査読有り]
     
    Abstract East Asian winter weather has altered dramatically in response to progressing climate change. However, analysis of time‐averaged atmospheric fields might obscure climate change signals that could relate to specific types of events. This study aimed to detect climate change signals for various background atmospheric fields by applying classification to daily surface pressure patterns. We found a pronounced trend of increase in surface air temperature over Japan since the 1980s, stronger than the seasonal mean trend, when dominating cold air advection from the Sea of Okhotsk. This cold air was warmed and humidified by the retreat of sea ice in the Sea of Okhotsk. In contrast, the warming trend was mitigated when warm air advection was dominant. These results highlight the importance of daily background atmospheric conditions in amplifying and localizing the impact of regional climate change.
  • Toru Terao, Shinjiro Kanae, Hatsuki Fujinami, Someshwar Das, A. P. Dimri, Subashisa Dutta, Koji Fujita, Azusa Fukushima, Kyung-Ja Ha, Masafumi Hirose, Jinkyu Hong, Hideyuki Kamimera, Rijan Bhakta Kayastha, Masashi Kiguchi, Kazuyoshi Kikuchi, Hyun Mee Kim, Akio Kitoh, Hisayuki Kubota, Weiquang Ma, Yaoming Ma, Millind Mujumdar, Masato I. Nodzu, Tomonori Sato, Z. Su, Shiori Sugimoto, Hiroshi G. Takahashi, Yuhei Takaya, Shuyu Wang, Kun Yang, Satoru Yokoi, Jun Matsumoto
    Bulletin of the American Meteorological Society 104 4 E884 - E908 2022年12月28日 [査読有り][招待有り]
     
    Abstract The Asian Precipitation Experiment (AsiaPEX) was initiated in 2019 to understand terrestrial precipitation over diverse hydroclimatological conditions for improved predictions, disaster reduction, and sustainable development across Asia under the framework of the Global Hydroclimatology Panel (GHP)/Global Energy and Water Exchanges (GEWEX). AsiaPEX is the successor to GEWEX Asian Monsoon Experiment (GAME, 1995-2005) and Monsoon Asian Hydro-Atmosphere Scientific Research and Prediction Initiative (MAHASRI, 2006-2016). While retaining the key objectives of the aforementioned projects, the scientific targets of AsiaPEX focus on land-atmosphere coupling and improvements to the predictability of the Asian hydroclimatological system. AsiaPEX was designed for both fine-scale hydroclimatological processes occurring at the land surface and the integrated Asian hydroclimatological system characterized by multiscale interactions. We adopt six approaches including observation, process studies, scale interactions, high-resolution hydrological modeling, field campaigns, and climate projection, which bridge gaps in research activities conducted in different regions. Collaboration with mesoscale and global modeling researchers is one of the core methods in AsiaPEX. We review these strategies based on the literature and our initial outcomes. These include the estimation and validation of high-resolution satellite precipitation, investigations of extreme rainfall mechanisms, field campaigns over the Maritime Continent and Tibetan Plateau, areas of significant impact on the entire AsiaPEX region, process studies on diurnal to interdecadal scale interactions, and evaluation of the predictabilities of climate models for long-term variabilities. We will conduct integrated observational and modeling initiative, the Asian Monsoon Year (AMY)-II around 2025-2028, whose strategies are the sub-regional observation platforms and integrated global analysis.
  • Kenta Tamura, Tomonori Sato
    International Journal of Climatology 42 15 7598 - 7610 2022年12月15日 [査読有り]
  • Yongkang Xue, Ismaila Diallo, Aaron A. Boone, Tandong Yao, Yang Zhang, Xubin Zeng, J. David Neelin, William K. M. Lau, Yan Pan, Ye Liu, Xiaoduo Pan, Qi Tang, Peter J. van Oevelen, Tomonori Sato, Myung-Seo Koo, Stefano Materia, Chunxiang Shi, Jing Yang, Constantin Ardilouze, Zhaohui Lin, Xin Qi, Tetsu Nakamura, Subodh K. Saha, Retish Senan, Yuhei Takaya, Hailan Wang, Hongliang Zhang, Mei Zhao, Hara Prasad Nayak, Qiuyu Chen, Jinming Feng, Michael A. Brunke, Tianyi Fan, Songyou Hong, Paulo Nobre, Daniele Peano, Yi Qin, Frederic Vitart, Shaocheng Xie, Yanling Zhan, Daniel Klocke, Ruby Leung, Xin Li, Michael Ek, Weidong Guo, Gianpaolo Balsamo, Qing Bao, Sin Chan Chou, Patricia de Rosnay, Yanluan Lin, Yuejian Zhu, Yun Qian, Ping Zhao, Jianping Tang, Xin-Zhong Liang, Jinkyu Hong, Duoying Ji, Zhenming Ji, Yuan Qiu, Shiori Sugimoto, Weicai Wang, Kun Yang, Miao Yu
    Bulletin of the American Meteorological Society 103 12 E2756 - E2767 2022年12月 [査読有り]
     
    Abstract Subseasonal-to-seasonal (S2S) precipitation prediction in boreal spring and summer months, which contains a significant number of high-signal events, is scientifically challenging and prediction skill has remained poor for years. Tibetan Plateau (TP) spring observed surface ­temperatures show a lag correlation with summer precipitation in several remote regions, but current global land–atmosphere coupled models are unable to represent this behavior due to significant errors in producing observed TP surface temperatures. To address these issues, the Global Energy and Water Exchanges (GEWEX) program launched the “Impact of Initialized Land Temperature and Snowpack on Subseasonal-to-Seasonal Prediction” (LS4P) initiative as a community effort to test the impact of land temperature in high-mountain regions on S2S prediction by climate models: more than 40 institutions worldwide are participating in this project. After using an innovative new land state initialization approach based on observed surface 2-m temperature over the TP in the LS4P experiment, results from a multimodel ensemble provide evidence for a causal relationship in the observed association between the Plateau spring land temperature and summer precipitation over several regions across the world through teleconnections. The influence is underscored by an out-of-phase oscillation between the TP and Rocky Mountain surface temperatures. This study reveals for the first time that high-mountain land temperature could be a substantial source of S2S precipitation predictability, and its effect is probably as large as ocean surface temperature over global “hotspot” regions identified here; the ensemble means in some “hotspots” produce more than 40% of the observed anomalies. This LS4P approach should stimulate more follow-on explorations.
  • Tomonori Sato, Tetsu Nakamura, Yoshihiro Iijima, Tetsuya Hiyama
    npj Climate and Atmospheric Science 5 1 2022年11月24日 [査読有り]
     
    Abstract Rapid Arctic warming has altered the regional hydrological cycle through reduction in Arctic sea ice. Observational and modeling efforts provided evidence that the enhanced evaporation from the Arctic Ocean could increase snowfall over high latitude terrestrial zones. However, questions remain regarding the amount of equatorward moisture transport and its change over the decadal timescale. Here we show that the transport of atmospheric moisture to Siberia that originated from Arctic Ocean evaporation has increased significantly in autumn to early winter during 1981–2019 when substantial sea ice retreat was observed. The enhanced Arctic moisture content is found in western Siberia in September, consistent with the observed increase in snow cover investigated in earlier studies. Meanwhile, the annual maximum daily amount of Arctic moisture shows a sharp increase in eastern Siberia during October–December associated with cyclonic activities along coastal regions. Our results suggest the importance of monitoring equatorward moisture transport during snow accumulation seasons because it could enhance local snowstorms as evaporation from the Arctic Ocean increases in the near future.
  • Shiori Sugimoto, Yongkang Xue, Tomonori Sato, Hiroshi G. Takahashi
    Climate Dynamics 2022年11月21日 [査読有り]
     
    Abstract Dynamical downscaling with a 20 km horizontal resolution was undertaken over East Asia for the period May–August in 1991–2015 using the Weather Research and Forecasting (WRF) model with Grell-3D ensemble cumulus parameterization as a product of the Impact of Initialized Land Temperature and Snowpack on Sub-Seasonal to Seasonal Prediction (LS4P) program. Simulated climatological precipitation biases were investigated over land during June when heavy precipitation occurred. Simulations underestimated precipitation along the Meiyu/Baiu rainband, while overestimating it farther north. Dry and wet biases expanded to south and north of the Yangtze River in China, respectively, marking years with poor precipitation simulations. Model biases in synoptic-scale circulation patterns indicate a weakened clockwise circulation over the western North Pacific in the model due to active convection there, and suppressed northward moisture transport to the Meiyu/Baiu rainband. Moisture convergence was slightly enhanced over central China due to an apparent anticyclonic circulation bias over northern China. In years with large biases, positive feedback between reduced moisture inflow and inactive convection occurred over southern China, while moisture transport to central China intensified on regional scales, with amplification of dry and wet biases over China. The Kain–Fritch scheme was used to test the influence of cumulus parameterization, improving the dry bias over southern China due to the modification of synoptic-scale circulation patterns in the lower troposphere. However, precipitation was further overestimated over central China, with the accuracy of precipitation distribution deteriorating.
  • Hatsuki Fujinami, Tomonori Sato, Hironari Kanamori, Masaya Kato
    Geophysical Research Letters 49 18 2022年09月28日 [査読有り]
  • Tetsu Nakamura, Tomonori Sato
    Environmental Research 209 112881 - 112881 2022年06月 [査読有り]
  • Daisuke Hatsuzuka, Tomonori Sato
    Journal of Geophysical Research: Atmospheres 127 9 2022年05月16日 [査読有り]
  • Shiori Sugimoto, Kenichi Ueno, Hatsuki Fujinami, Tomoe Nasuno, Tomonori Sato, Hiroshi G. Takahashi
    JOURNAL OF HYDROMETEOROLOGY 22 12 3171 - 3188 2021年12月 [査読有り]
     
    A numerical experiment with a 2-km resolution was conducted using the Weather Research and Forecasting (WRF) Model to investigate physical processes driving nocturnal precipitation over the Himalayas during the mature monsoon seasons between 2003 and 2010. The WRF Model simulations of increases in precipitation twice a day, one in the afternoon and another around midnight, over the Himalayan slopes, and of the single nocturnal peak over the Himalayan foothills were reasonably accurate. To understand the synoptic-scale moisture transport and its local-scale convergence generating the nocturnal precipitation, composite analyses were conducted using the reanalysis dataset and model outputs. In the synoptic scale, moisture transport associated with the westward propagation of low pressure systems was found when nocturnal precipitation dominated over the Himalayan slopes. In contrast, moisture was directly provided from the synoptic-scale monsoon westerlies for nocturnal precipitation over the foothills. The model outputs suggested that precipitation occurred on the mountain ridges in the Himalayas during the afternoon and expanded horizontally toward lower-elevation areas through the night. During the nighttime, the downslope wind was caused by radiative cooling at the surface and was intensified by evaporative cooling by hydrometeors in the near-surface layer. As a result, convergence between the downslope wind and the synoptic-scale flow promoted nocturnal precipitation over the Himalayas and to the south, as well as the moisture convergence by orography and/or synoptic-scale circulation patterns. The nocturnal precipitation over the Himalayas was not simulated well when we used the coarse topographic resolution and the smaller number of vertical layers.SIGNIFICANCE STATEMENT: Nocturnal precipitation is observed over the Himalayan slopes and foothills during summer. We investigated physical factors to cause the nocturnal precipitation there using a reanalysis dataset and a numerical simulation with 2-km horizontal resolution. Water vapor was intensively transported to the Himalayas between midnight and morning in the synoptic scale, and then generated precipitation under the influence of mountain topography. A downslope wind, which occurred in association with nocturnal cooling of land surface, enhanced a moisture convergence and caused precipitation over the Himalayan slopes and foothills. Evaporative cooling from the precipitation also contributed the cooling in the near-surface layer, which assisted an intensification of the nocturnal downslope wind.
  • Daisuke Hatsuzuka, Tomonori Sato, Yoshihito Higuchi
    npj Climate and Atmospheric Science 4 1 2021年12月 [査読有り]
     
    AbstractThe intensity of extreme precipitation has been projected to increase with increasing air temperature according to the thermodynamic Clausius–Clapeyron (C-C) relation. Over the last decade, observational studies have succeeded in demonstrating the scaling relationship between extreme precipitation and temperature to understand the projected changes. In mid-latitude coastal regions, intense precipitation is strongly influenced by synoptic patterns and a particular characteristic is the long-lasting heavy precipitation driven by abundant moisture transport. However, the effect of synoptic patterns on the scaling relationship remains unclear. Here we conduct an event-based analysis using long-term historical records in Japan, to distinguish extreme precipitation arising from different synoptic patterns. We find that event peak intensity increases more sharply in persistent precipitation events, which lasted more than 10 h, sustained by atmospheric river-like circulation patterns. The long duration-accumulated precipitation extremes also increase with temperature at a rate considerably above the C-C rate at higher temperatures. Our result suggests that long-lasting precipitation events respond more to warming compared with short-duration events. This greatly increases the risks of future floods and landslides in the mid-latitude coastal regions.
  • Md. Anowarul Islam, Tomonori Sato
    Water 13 20 2915 - 2915 2021年10月16日 [査読有り]
     
    The coastal area of Bangladesh is highly vulnerable to extreme sea levels because of high population exposure in the low-lying deltaic coast. Since the area lies in the monsoon region, abundant precipitation and the resultant increase in river discharge have raised a flood risk for the coastal area. Although the effects of atmospheric forces have been investigated intensively, the influence of precipitation on extreme sea levels in this area remains unknown. In this study, the influence of precipitation on extreme sea levels for three different stations were investigated by multivariate regression using the meteorological drivers of precipitation, sea level pressure, and wind. The prediction of sea levels considering precipitation effects outperformed predictions without precipitation. The benefit of incorporating precipitation was greater at Cox’s Bazar than at Charchanga and Khepupara, reflecting the hilly landscape at Cox’s Bazar. The improved prediction skill was mainly confirmed during the monsoon season, when strong precipitation events occur. It was also revealed that the precipitation over the Bangladesh area is insensitive to the El Niño-Southern Oscillation and Indian Ocean Dipole mode. The precipitation over northern Bangladesh tended to be high in the year of a high sea surface temperature over the Bay of Bengal, which may have contributed to the variation in sea level. The findings suggest that the effect of precipitation plays an essential role in enhancing sea levels during many extreme events. Therefore, incorporating the effect of terrestrial precipitation is essential for the better prediction of extreme sea levels, which helps coastal management and reduction of hazards.
  • Hiromichi Sakurai, Masanobu Yamamoto, Osamu Seki, Takayuki Omori, Tomonori Sato
    Geochemistry, Geophysics, Geosystems 22 9 2021年09月 [査読有り]
     
    The cellulose delta O-18 of plant tissues in peat is a potential climate proxy. However, understanding what is driving the shifts in delta O-18 of cellulose is required for its application. Here, we analyzed the delta O-18 values of Sphagnum and vascular plant cellulose, as well as the delta O-18 and delta D values of pore water, in a 4-m-long peat core from the Bekanbeushi ombrotrophic bog to understand paleoclimatic changes in northern Japan over the past 2,000 years. The cellulose delta O-18 values of Sphagnum were lower than those of vascular plant tissues, although both draw water from the same layer. Whereas the cellulose delta O-18 values of Sphagnum more directly reflect those of precipitation, those of vascular plants become enriched through transpiration. Thus, the difference between vascular plants and Sphagnum (Delta delta O-18(vp-sp)) is a potential proxy for relative humidity. Cellulose delta O-18 of Sphagnum revealed centennial variations with maxima around 800, 1300, and 1500 CE and minima around 500, 1000, 1700, and 1900 CE. The Delta delta O-18(vp-sp) was inversely correlated with Sphagnum cellulose delta O-18, indicating that the axis of summer westerlies was more frequently located to the north and the climate was moist in the former periods, whereas the axis of summer westerlies was generally located to the south and the climate was dry in the latter periods. These results suggest a warm and moist climate during the former periods due to frequent rainy summers driven by strong East Asian summer monsoon activity, and the opposite conditions in the latter periods.
  • Yongkang Xue, Tandong Yao, Aaron A. Boone, Ismaila Diallo, Ye Liu, Xubin Zeng, William K. M. Lau, Shiori Sugimoto, Qi Tang, Xiaoduo Pan, Peter J. van Oevelen, Daniel Klocke, Myung-Seo Koo, Tomonori Sato, Zhaohui Lin, Yuhei Takaya, Constantin Ardilouze, Stefano Materia, Subodh K. Saha, Retish Senan, Tetsu Nakamura, Hailan Wang, Jing Yang, Hongliang Zhang, Mei Zhao, Xin-Zhong Liang, J. David Neelin, Frederic Vitart, Xin Li, Ping Zhao, Chunxiang Shi, Weidong Guo, Jianping Tang, Miao Yu, Yun Qian, Samuel S. P. Shen, Yang Zhang, Kun Yang, Ruby Leung, Yuan Qiu, Daniele Peano, Xin Qi, Yanling Zhan, Michael A. Brunke, Sin Chan Chou, Michael Ek, Tianyi Fan, Hong Guan, Hai Lin, Shunlin Liang, Helin Wei, Shaocheng Xie, Haoran Xu, Weiping Li, Xueli Shi, Paulo Nobre, Yan Pan, Yi Qin, Jeff Dozier, Craig R. Ferguson, Gianpaolo Balsamo, Qing Bao, Jinming Feng, Jinkyu Hong, Songyou Hong, Huilin Huang, Duoying Ji, Zhenming Ji, Shichang Kang, Yanluan Lin, Weiguang Liu, Ryan Muncaster, Patricia de Rosnay, Hiroshi G. Takahashi, Guiling Wang, Shuyu Wang, Weicai Wang, Xu Zhou, Yuejian Zhu
    Geoscientific Model Development 14 7 4465 - 4494 2021年07月21日 [査読有り]
     
    Abstract. Subseasonal-to-seasonal (S2S) prediction, especially the prediction of extreme hydroclimate events such as droughts and floods, is not only scientifically challenging, but also has substantial societal impacts. Motivated by preliminary studies, the Global Energy and Water Exchanges (GEWEX)/Global Atmospheric System Study (GASS) has launched a new initiative called “Impact of Initialized Land Surface Temperature and Snowpack on Subseasonal to Seasonal Prediction” (LS4P) as the first international grass-roots effort to introduce spring land surface temperature (LST)/subsurface temperature (SUBT) anomalies over high mountain areas as a crucial factor that can lead to significant improvement in precipitation prediction through the remote effects of land–atmosphere interactions. LS4P focuses on process understanding and predictability, and hence it is different from, and complements, other international projects that focus on the operational S2S prediction. More than 40 groups worldwide have participated in this effort, including 21 Earth system models, 9 regional climate models, and 7 data groups. This paper provides an overview of the history and objectives of LS4P, provides the first-phase experimental protocol (LS4P-I) which focuses on the remote effect of the Tibetan Plateau, discusses the LST/SUBT initialization, and presents the preliminary results. Multi-model ensemble experiments and analyses of observational data have revealed that the hydroclimatic effect of the spring LST on the Tibetan Plateau is not limited to the Yangtze River basin but may have a significant large-scale impact on summer precipitation beyond East Asia and its S2S prediction. Preliminary studies and analysis have also shown that LS4P models are unable to preserve the initialized LST anomalies in producing the observed anomalies largely for two main reasons: (i) inadequacies in the land models arising from total soil depths which are too shallow and the use of simplified parameterizations, which both tend to limit the soil memory; (ii) reanalysis data, which are used for initial conditions, have large discrepancies from the observed mean state and anomalies of LST over the Tibetan Plateau. Innovative approaches have been developed to largely overcome these problems.
  • Hatsuki Fujinami, Koji Fujita, Nobuhiro Takahashi, Tomonori Sato, Hironari Kanamori, Sojiro Sunako, Rijan B. Kayastha
    Journal of Geophysical Research: Atmospheres 126 13 2021年07月16日 [査読有り]
  • Kevin Ray Español Lucas, Tomonori Sato, Masamichi Ohba
    Energies 14 8 2310 - 2310 2021年04月20日 [査読有り]
     
    Wind energy development has been limited by concerns associated to the varying features in wind speed which tends to destabilize the power system. This study aims to clarify the variability of winds within a day in the Philippines, specifically the hourly changes of onshore horizontal winds at 100-m hub-heights. A whole one-year experiment using the Weather Research and Forecasting model shows that onshore wind speeds decrease during the transitional hours between land breeze and sea breeze. The decreases in wind speed are most significant over coastal regions with high sloping topography. The extreme decreases in wind speed during morning hours, due to the natural processes, are found to often occur at the same time as the extreme electricity undersupply caused by the morning increase in energy demand. This result warns that the power system stability in the Philippines may become more sensitive to the variability of wind as the share of wind energy generation increases in the future. The findings of this study can contribute to promote sustainability in the operation of existing wind-reliant power systems and planning of future wind energy developments.
  • Muhammad Mubashar Dogar, Tomonori Sato, Fei Liu
    Scientific Reports 10 1 2020年12月 [査読有り][通常論文]
  • Nagai Shin, Ayumi Kotani, Tomonori Sato, Atsuko Sugimoto, Trofim C. Maximov, Aleksandr Nogovitcyn, Yumiko Miyamoto, Hideki Kobayashi, Shunsuke Tei
    Polar Science 25 100550 - 100550 2020年09月 [査読有り][通常論文]
     
    Accurate calculation of leaf area index (LAI) in boreal forests, which are vulnerable to climate change and have insufficient ground-truth data, is an important but challenging task when evaluating the spatio-temporal variability of ecosystem structures and functions (photosynthesis and evapotranspiration). By applying a direct method, we calculated the LAI of multiple forest layers (i.e., overstory of larch; understory of birch, willow, and alder; and floor vegetation) in a deciduous needle-leaf forest with a somewhat open canopy in eastern Siberia. We performed field studies that included logging one overstory larch tree, harvesting leaves of larch and floor vegetation (e.g., Vaccinium vitis-idaea), sampling leaves of understory trees, and measuring the architecture and morphology of overstory and understory trees and leaves. The plot-scale LAIs of larch overstory, understory trees, and floor vegetation were 1.30, 0.50, and 0.51, respectively, for a total of 2.31. Sum of our plot-scale LAI of larch overstory and understory trees was similar to previously reported results based on indirect methods. Our results indicate that LAI of understory trees and forest floor vegetation is important to improve the accuracy of total LAI of a deciduous needle-leaf forest with a somewhat open canopy in eastern Siberia.
  • Daisuke Hatsuzuka, Tomonori Sato, Kohei Yoshida, Masayoshi Ishii, Ryo Mizuta
    Scientific Online Letters on the Atmosphere 16 0 23 - 29 2020年02月 [査読有り][通常論文]
  • Kenta TAMURA, Tomonori SATO
    Journal of the Meteorological Society of Japan. Ser. II 98 6 1261 - 1277 2020年 [査読有り][通常論文]
  • Tetsu Nakamura, Koji Yamazaki, Tomonori Sato, Jinro Ukita
    Nature Communications 10 1 2019年11月 [査読有り][通常論文]
  • Muhammad Mubashar Dogar, Tomonori Sato
    Journal of Geophysical Research: Atmospheres 124 14 7580 - 7598 2019年07月27日 [査読有り][通常論文]
  • Tomonori Sato, Tetsu Nakamura
    Scientific Reports 9 1 2019年07月 [査読有り][通常論文]
  • Hiroki Teramura, Tomonori Sato, Kenta Tamura
    Scientific Online Letters on the Atmosphere 15 0 143 - 148 2019年05月31日 [査読有り][通常論文]
  • Hatsuzuka, D, T. Sato
    Journal of Hydrometeorology 20 3 563 - 574 2019年03月 [査読有り][通常論文]
     
    Abstract This study investigated future changes in monthly extreme precipitation in Japan during summer (June–August). The uncertainties in estimating extreme monthly precipitation were analyzed using large-ensemble regional climate simulations for both present and 4-K warmer climates. The main diagnostics were based on the 100-yr return values of monthly total precipitation PT100 estimated from a best-fit probability distribution. Under the warmer climate, PT100 was projected to increase in approximately 87%, 88%, and 78% of the total number of stations for June, July, and August, respectively, suggesting that once-per-century monthly precipitation will increase as temperature increases over a wide area of Japan, although large regional variations will exist. The western part of Kyushu and the Hokkaido region showed significant and moderately robust increases in PT100 throughout the summer months. In contrast, a considerable and robust increase was projected only in June in the Nansei Islands. The percentage change in PT100 was small in western and eastern Japan, and thus the sign of the change was uncertain. Further analysis indicated that uncertainty in internal variability is more important than uncertainty in the SST scenario for future projections of monthly precipitation extremes.
  • Ta-Huu. C, T. Sato
    International Journal of Climatology 39 2461 - 2473 2019年 [査読有り][通常論文]
  • Habib, S. M. A, T. Sato, D. Hatsuzuka
    Atmospheric Science Letters 20 e879 e879 - e879 2019年01月 [査読有り][通常論文]
  • Fujita, M, T. J. Yamada, T. Sato, S. Kawazoe, M. Nakano, K. Ito
    気象集誌 2019年 [査読有り][通常論文]
  • 星野剛, 山田朋人, 稲津將, 佐藤友徳, 川瀬宏明, 杉本志織
    土木学会論文集B1(水工学) 74 5 I_13 - I_18 2018年11月 [査読有り][通常論文]
  • Dogar M. M, F. Kucharski, T. Sato, S. Mehmood, S Ali, Z. Gong, D. Das, J. Arraut
    Global and Planetary Change 172 223 - 241 2018年10月 [査読有り][通常論文]
  • Boniface Wainaina Kariuki, Tomonori Sato
    RENEWABLE ENERGY 116 88 - 96 2018年02月 [査読有り][通常論文]
     
    Kenya is faced with a rising demand in electricity resulting from a rapidly growing economy and an increasing population. Being a tropical country, lying astride the equator, solar energy is one of the readily available renewable energy resource options to meet this need. Unfortunately, there is still very low adoption of solar systems in the country which could be majorly attributed to lack of adequate solar resource assessment. Besides, past studies" on this area in Kenya only focused on the available amount of solar resource leaving out the issue of variability. To bridge this gap, the temporal and spatial variability of global horizontal irradiance (GHI) and direct normal Irradiance (DNI) is analyzed using 19-year long (1995-2013) Meteosat satellite dataset. GHI interannual variability is low in most parts of the country but DNI has a clearly higher variability except a few locations in the East and Northern desert. Low spatial variability for GHI was recorded for locations within 1225 km(2) while DNI variability was double that of GHI. The results offer readers a quick reference of variability of solar resource at different locations in Kenya which is useful in guiding measurement requirements and consequently in promoting deployment of solar systems. (C) 2017 The Authors. Published by Elsevier Ltd.
  • Erdenebat Enkhbat, Sato Tomonori
    Progress in Earth and Planetary Science 5 2018年 [査読有り][通常論文]
  • 田村 健太, 佐藤 友徳
    雪氷研究大会講演要旨集 2018 99  公益社団法人 日本雪氷学会／日本雪工学会 2018年
  • Fujita, M, R. Mizuta, M. Ishii, H. Endo, T. Sato, Y. Okada, S. Kawazoe, S. Sugimoto, K. Ishihara, S. Watanabe
    Geophysical Research Letters 45 2018年 [査読有り][通常論文]
  • Dogar, M. M, T. Sato
    Journal of Geophysical Research Atmospheres 123 13074 - 13091 2018年 [査読有り][通常論文]
  • Hatsuki Fujinami, Tomonori Sato, Hironari Kanamori, Fumie Murata
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 122 18 9591 - 9610 2017年09月 [査読有り][通常論文]
     
    Precipitation features around the Meghalaya Plateau, northeast India, during summer are investigated using a 17 year (1998-2014) high-spatial-resolution Tropical Rainfall Measuring Mission precipitation radar data set. Precipitation around the plateau fell into two distinct regimes based on the low-level wind direction that fluctuates on intraseasonal time scales over Bangladesh, windward of the plateau: a westerly regime (WR) and an easterly regime (ER). Under the WR, strong low-level onshore southwesterlies across Bangladesh encounter the plateau, and localized strong low-level southerlies running parallel to the Arakan Mountains (i.e., the barrier jet) also blow toward the plateau, concentrating convective unstable air onto its southern slopes. The low-level wind fields and large-scale upper level divergent fields promote frequent and intense orographic rainfall along the southern slopes due to forced uplift, generating high precipitation. In contrast, under the ER, strong southeasterlies that blow along the Gangetic Plain without encountering the plateau and subsidence inhibit upward motion around the plateau, resulting in low precipitation. Diurnal variations in precipitation significantly affect the daily precipitation around the plateau under both regimes. High rainfall frequency persists over the southern slopes between 2100 and 1200 LT of the next day under the WR, whereas modest rainfall frequency occurs between 0000 and 0600 LT under the ER, with a daytime minimum and nocturnal maximum in both regimes. The atmospheric boundary layer processes over Bangladesh regulate the wind speed and vertical structure of the low-level wind toward the plateau, with deceleration during daytime and acceleration at night (i.e., nocturnal jet) that result in the nocturnal rainfall maximum. Plain Language Summary The Meghalaya Plateau of northeast India is one of the wettest places in the world. Extreme rainfall often causes flooding across the flat lowlands of Bangladesh to the south of the plateau. This study reveals the features contributing to this heavy rainfall and the mechanisms responsible using a 17 year (1998-2014) high-spatial-resolution spaceborne precipitation radar (TRMM-PR) data set and state-of-the-art atmospheric circulation data (ERA-Interim). Precipitation around the plateau is highly sensitive to whether strong low-level southerly monsoon winds from the ocean have westerly or easterly components (westerly and easterly regimes, respectively) over Bangladesh, windward of the plateau. Under the westerly regime, strong low-level southwesterlies blow over Bangladesh directly toward the plateau and localized strong low-level southerlies running parallel to the Arakan Mountains also blow toward the plateau. These winds concentrate moist air onto the southern slopes of the plateau, and rainfall occurs as the air is forced upward. The large rainfall amounts are caused by frequent heavy rain. In contrast, under the easterly regime, strong southeasterlies blow along the Gangetic Plain through northwestern Bangladesh and avoid the plateau, resulting in less frequent and lighter rain around the plateau.
  • Mikiko Fujita, Tomonori Sato
    SCIENTIFIC REPORTS 7 2017年07月 [査読有り][通常論文]
     
    Extremely heavy precipitation affects human society and the natural environment, and its behaviour under a warming climate needs to be elucidated. Recent studies have demonstrated that observed extreme precipitation increases with surface air temperature (SAT) at approximately the Clausius-Clapeyron (CC) rate, suggesting that atmospheric water vapour content can explain the relationship between extreme precipitation and SAT. However, the relationship between atmospheric water vapour content and SAT is poorly understood due to the lack of reliable observations with sufficient spatial and temporal coverage for statistical analyses. Here, we analyse the relationship between atmospheric water vapour content and SAT using precipitable water vapour (PWV) derived from global positioning system satellites. A super-CC rate appears in hourly PWV when the SAT is below 16 degrees C, whereas the rate decreases at high SAT, which is different from the precipitation-SAT relationship. The effects of upper air temperature and water vapour can consistently explain the super-CC rate of PWV relative to SAT. The difference between moist and dry adiabatic lapse rates increases with SAT, in consequence of more ability to hold water vapour in the free atmosphere under higher SAT conditions; therefore, attainable PWV increases more rapidly than the CC rate as SAT increases.
  • 佐藤 友徳, 田村 健太
    雪氷研究大会講演要旨集 2017 264 - 264 公益社団法人 日本雪氷学会／日本雪工学会 2017年
  • Manabu Nemoto, Tomoyoshi Hirota, Tomonori Sato
    JOURNAL OF AGRICULTURAL METEOROLOGY 72 3-4 167 - 172 2016年09月 [査読有り][通常論文]
     
    This paper investigates the shifts in climatic suitability for cultivating grapes (Vitis vinifera) in Hokkaido, Japan, throughout the 20th and 21st century. To assess area suitability over time, we used two climate model datasets and three climatic criteria (summer temperature, summer precipitation, and winter temperature). The optimum area for growth gradually enlarged from the 1990s to present (2010s), and this area will cover almost all of the Hokkaido region by the 2050s. Even when considering model uncertainties, almost all low elevation areas in Hokkaido are projected to be suitable for V. vinifera cultivation in the future.
  • Shinji Matsumura, Takeshi Horinouchi, Shiori Sugimoto, Tomonori Sato
    JOURNAL OF CLIMATE 29 8 3075 - 3093 2016年04月 [査読有り][通常論文]
     
    The Pacific Japan (PJ) teleconnection pattern leads to a meridional precipitation dipole between the subtropics and East Asia in the summer of El Nino decaying years. However, observational analysis and model experiments indicate that increased sea surface temperature (SST) in the Kuroshio Oyashio Extension (KOE) region, where a strong northward-decreasing SST gradient occurs, induces a northward shift of baiu rainfall with the subtropical jet, forming a tripolar precipitation anomaly pattern over the northwest Pacific. In July, the leading empirical orthogonal function (EOF) mode for precipitation represents the meridional dipole between subtropical and baiu rainfalls, while EOF-2 features the northward-shifted baiu rainband. The PJ atmospheric forcing increases KOE SST, which enhances northward shifts in the subtropical jet and baiu rainband, resulting in oceanic forcing over the KOE. In experiments using a regional climate model the subtropical jet response to KOE SST forcing explains about 20% of the anomalies in the control experiment. The northward-shifted baiu condensational heating also enhances the northward shift of the subtropical jet with a northeastward extension. In August when the baiu rainband disappears, the northward shift of the subtropical jet is enhanced mainly by KOE SST variability. During the summer, as a result of increased KOE SST and the northward-shifted baiu heating, cyclonic anomalies intensify over the Sea of Okhotsk and anticyclonic anomalies intensify over the northwest Pacific, affecting the western Pacific subtropical high. The results suggest that air sea interaction over the KOE must be considered to better understand the summer northwest Pacific climate.
  • Enkhbat Erdenebat, Tomonori Sato
    ATMOSPHERIC SCIENCE LETTERS 17 2 135 - 140 2016年02月 [査読有り][通常論文]
     
    A 30-year meteorological station and reanalysis datasets revealed that the frequency and intensity of hot extremes have increased dramatically around Mongolia since the late 1990s. Many recent heat waves (HWs) were triggered by atmospheric forcing with a mid-tropospheric ridge pattern which appears frequently around Mongolia in 2000s. An observational data analysis for each HW event indicates that the rate of temperature increase at the beginning stage of HW is sensitive to the soil moisture condition. Therefore, it is suggested that the recent drier soil conditions played a role in enhancing the frequency and intensity of HWs and localization around Mongolia.
  • 佐藤 友徳, 田村 健太
    雪氷研究大会講演要旨集 2016 146  公益社団法人 日本雪氷学会／日本雪工学会 2016年
  • Hiroshi G. Takahashi, Sachiho A. Adachi, Tomonori Sato, Masayuki Hara, Xieyao Ma, Fujio Kimura
    JOURNAL OF CLIMATE 28 18 7128 - 7144 2015年09月 [査読有り][通常論文]
     
    This study used a 4-km resolution regional climate model to examine the sensitivity of surface air temperature on the Pacific coast of Japan to sea surface temperature (SST) south of the Pacific coast of Japan during summer. The authors performed a control simulation (CTL) driven by reanalysis and observational SST datasets. A series of sensitivity experiments using climatological values from the CTL SST datasets over a 31-yr period was conducted. The interannual variation in surface air temperature over the Pacific coast was well simulated in CTL. The interannual variation in SST over the Kuroshio region amplified the interannual variation in surface air temperature over the Pacific coast. It was found that 30% of the total variance of interannual variation in surface air temperature can be controlled by interannual variation in SST. The calculated surface air temperature on the Pacific coast increased by 0.4 K per 1-K SST warming in the Kuroshio region. Note that this sensitivity was considerably greater during nighttime than during daytime. Concurrent with the warming in surface air temperature, downward longwave radiation at the surface was also increased. In summer, the increase in latent heat flux was considerably larger than that in sensible heat flux over the ocean because of SST warming, according to the temperature dependence of the Bowen ratio. This implies that the primary factor for the increase in surface air temperature in summer is increased moisture in the lower troposphere, indicating that the regional warming was caused by an increase in H2O greenhouse gas.
  • Masaru Inatsu, Tomonori Sato, Tomohito J. Yamada, Ryusuke Kuno, Shiori Sugimoto, Murad A. Farukh, Yadu N. Pokhrel, Shuichi Kure
    ATMOSPHERIC SCIENCE LETTERS 16 3 297 - 304 2015年07月 [査読有り][通常論文]
     
    The experiments with three general circulation models (GCMs) by three regional atmospheric models (RAMs) for the dynamical downscaling (DDS) have been performed to evaluate the uncertainty in the global warming response during summertime in Hokkaido, Japan. The results of a 10-year RAM integration nested into GCM under present or future climate conditions were synthesized after applying bias correction. For the target decades during which the global-mean temperature increases by 2 K in each GCM, the DDS results indicate that surface air temperature and precipitation mostly depend on the GCM imposed as the lateral boundary condition.
  • Shiori Sugimoto, Tomonori Sato, Tomonori Sasaki
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 120 11 5437 - 5445 2015年06月 [査読有り][通常論文]
     
    The influence of historical urbanization on warming trends observed on Hokkaido Island (Japan) is discussed with an emphasis on seasonally and diurnally differential responses of air temperature to urban effects. Two numerical experiments using past and current land use scenarios successfully simulated the observed temperature trends, showing a greater rate of warming in winter than in summer and a greater increase in daily minimum than daily maximum temperatures. The results suggest that seasonal and diurnal variations in the thermal structure of the planetary boundary layer play a leading role in determining the warming rate of surface air. Under strongly stable stratification, anomalous heating within the urban canopy dissipates into a near-surface shallow layer, resulting in increased daily minimum temperatures during winter. In summer, however, anomalous urban heating due to increased Bowen ratios is attenuated by vertical mixing in the convective daytime boundary layer, suppressing the impact of urban heating on surface warming.
  • Shinji Matsumura, Shiori Sugimoto, Tomonori Sato
    JOURNAL OF CLIMATE 28 7 2873 - 2883 2015年04月 [査読有り][通常論文]
     
    The summer western Pacific subtropical high (WPSH) has intensified during the past three decades. However, the underlying mechanism is not yet well understood. Here, it is shown that baiu rainband activity in midsummer, which is part of the East Asian summer monsoon, plays an important role in recent intensification in the WPSH along the baiu rainband. In contrast with the WPSH, the summer Okhotsk high, which is located to the north of the baiu rainband, has weakened during the past three decades. The north-south contrasting changes between the two highs reflect a response to northward-moved and enhanced baiu heating, which intensifies the upper-tropospheric ridge, resulting in the baroclinic intensification of the WPSH. Regional climate model experiments also support the observational analysis. Therefore, baiu convective activity in midsummer can act as a major driver for the WPSH intensification. The results here suggest that the mechanism intensifying the summer North Pacific subtropical high clearly differs between the western and eastern Pacific.
  • 地域気候変動の不確実性を考慮した北海道におけるてん菜糖量の将来変化
    友貞俊成, 佐藤友徳
    北海道の農業気象 67 13 - 21 2015年 [査読有り][通常論文]
  • Ayuma Shimokawabe, Yuichi Yamaura, Takumi Akasaka, Tomonori Sato, Yuichiro Shida, Satoshi Yamanaka, Futoshi Nakamura
    PloS one 10 8 e0135732  2015年 [査読有り][通常論文]
     
    It has recently been proposed that microrefugia played an important role in species survival during past climate change events. However, the current distributions of microrefugia remain largely unknown. Wind-hole sites are areas affected by preferential flows of cool air generated in interstitial spaces created by rock fragments or colluvia. Alpine plant species occurring in lowland wind-hole sites isolated from alpine zones may be relicts of the last glacial period. Hokkaido, northern Japan, is known to contain many wind-hole sites in which alpine plant species can occur. Here we surveyed 55 wind-hole sites in the Kitami region, eastern Hokkaido, and observed two alpine plant species (lingonberry, Vaccinium vitis-idaea, and Labrador tea, Rhododendron groenlandicum ssp. diversipilosum var. diversipilosum) in 14 wind-hole sites. Statistical modeling showed that wind-hole sites are likely to occur in areas with high maximum slope angles and volcanic rock cover, and concave surfaces. Our predictions of wind-hole site distributions suggest that such topographic conditions are common in our study area, and that many undiscovered wind-hole sites exist. Ignoring microhabitats may greatly underestimate species distributions in topographically complex regions, and dispersed cool spots may also function as stepping stones and temporal habitats for cold-adapted species. Because these localized unique habitats usually occur in economically unproductive sites, identifying and protecting potential microrefugia (cool spots) would be a robust and cost-effective mitigation of climate change impacts.
  • Shinji Matsumura, Koji Yamazaki, Tomonori Sato
    JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 93 2 229 - 244 2015年 [査読有り][通常論文]
     
    We investigate the formation mechanism of the summer Okhotsk High (OH) in terms of the land-atmosphere coupling in Siberia. A reanalysis data indicates that the formation mechanism of the OH clearly differs between early and late summer because it changes from a nearly barotropic to a baroclinic structure with seasonal changes. Then, we assess the influence of springtime snow cover on the formation of the late summer OH with the baroclinicity using a regional climate model. The model performs well in reproducing the land-atmosphere coupling in eastern Siberia and the OH in August 2008, when abnormal weather prevails in Japan, in conjunction with the intensively developed OH. The August OH develops with a distinct baroclinic structure owing to increased surface heating, which is related to land-atmosphere coupling in response to reduced spring snow cover in eastern Siberia. The land-atmosphere coupling can help to reinforce and maintain the baroclinic structure through surface heating, forming strong surface anticyclone to the southeast over the Sea of Okhotsk. Our results suggest that the late summer OH is a regional climate system that involves coupling among the atmosphere, the cool ocean, and the warm land surface.
  • Shiori Sugimoto, Tomonori Sato, Tomonori Sasaki
    SOLA 11 95 - 99 2015年 [査読有り][通常論文]
     
    The effect of historical land-use change on winter precipitation in Hokkaido, Japan is evaluated by sensitivity experiments using a regional climate model and past and current land-use maps. The regional climate model successfully simulates winter precipitation characteristics, such as heavy precipitation in central mountain areas and around the Japan Sea coast, and a gradual decrease in precipitation from west to east. A comparison of model simulations using 1850 and 1985 land-use maps shows that precipitation has decreased approximately 1.7 mm mon(-1), especially over deforested areas. This decrease is mainly a result of reduced evapotranspiration (approximately 2.4 mm mon(-1)) from lower net radiation associated with increased snow cover and higher surface albedo. Meanwhile, precipitation has increased in mountainous areas and on leeward slopes as a result of intensified upward air motion, which is attributed to a decrease in surface roughness caused by deforestation and the strengthening of horizontal wind speeds.
  • Keisuke Mori, Tomonori Sato
    JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 93 5 581 - 592 2015年 [査読有り][通常論文]
     
    Climate monitoring in urban areas is important because climate change in densely populated areas has a strong influence on society. The rate of long-term temperature increase in high-latitude snowy urban areas is relatively large due to global warming and urban heat islands. However, the influence of snow cover on urban heat islands is unclear. The purpose of this study is to assess the effect of snow cover in urban canopy layer on winter heat islands using a mesoscale atmospheric model coupled with an urban canopy model. Numerical experiments indicate that snow cover in urban areas serves to decrease surface air temperature, with a stronger decrease in daily maximum temperatures (0.4-0.6 degrees C) than daily minimum temperatures (0.1-0.3 degrees C). The increase in surface albedo is primarily responsible for the decrease in net shortwave radiation and sensible heat flux. In addition, increased evaporation causes a weakened sensible heat flux. The estimated snow cover effect during the day is comparable with the typical magnitude of anthropogenic heat release. In urban canopy layer, snow cover on roofs plays a significant role in reducing surface air temperature. Snow clearing on roads tends to increase nocturnal surface air temperature, especially in suburban areas because decreased snow depth increases ground heat transfer. These results indicate that snow cover in urban canopy layer reduces surface air temperature, resulting in weakened urban heat islands.
  • Yamada, T. J, M. A. Farukh, T. Fukushima, M. Inatsu, T. Sato, Y. N. Pokhrel, T. Oki
    Hydro. Res. Lett 8 4 108 - 113 THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES 2014年 [査読有り][通常論文]
     
    This paper introduces a method named "hybrid-downscaling" to estimate the future extreme hourly precipitation intensity based on observational evidence of the 99th percentile precipitation intensity against air temperature in Sapporo and Tokyo, Japan. The future projected air temperature under the Special Report on Emissions Scenarios (SRES) A1B was used after dynamical downscaling using 3 different regional atmospheric models (RAMs) with lateral boundary conditions from 3 different general circulation models (GCMs). We analyzed the 99th percentile of hourly precipitation intensity against daily mean air temperature in Sapporo and Tokyo. The 99th percentile precipitation intensity tended to have an approximate equation in which the rate of increment was similar to the Clausius-Clapeyron rate of change in the saturated water vapor. This study also showed that the precipitable water vapor and the convective instability followed the Clausius-Clapeyron-like rate of change during the hours with the 99th percentile precipitation intensity.
  • Keisuke Mori, Tomonori Sato
    JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 92 4 327 - 346 2014年 [査読有り][通常論文]
     
    This study investigated the spatiotemporal characteristics of high-temperature events in Hokkaido, Japan, using observational data of 26 years. Statistical analyses revealed that the annual mean frequency of these events was lower (higher) at stations on the western (eastern) side of Hokkaido. The frequency of these events showed clear seasonal variation with two distinct peaks occurring in January and May. In addition, the local time of the high-temperature onset was strongly dependent on the season; the onset occurred more frequently from 1600 to 0400 Japan Standard Time (JST) in January and from 0700 to 1300 JST in May. The seasonal dependence mechanism of the high-temperature onset was investigated in eastern Hokkaido, where the frequencies of both January and May high-temperature events were the highest. In January, an extratropical cyclone passage caused intensified warm advection and increased precipitable water vapor, leading to weakened radiative cooling during the night. In May, the high-temperature events were triggered by two different mechanisms related to solar insolation. The first mechanism is explained by dynamic foehn, which forms the subsidence of the high potential temperature layer on the lee of mountains. However, the nocturnal inversion layer prevented vertical mixing of the foehn-induced warm air aloft and cold air near the ground. The surface air temperature dramatically increased after sunrise when the nocturnal inversion layer disappeared. The second mechanism is explained by the combination of airflow diabatically heated by surface sensible heat flux and dynamic foehn. Therefore, solar insolation is the key factor that controlled the diurnal variation in high-temperature events in May.
  • Akemi Tanaka, Tomonori Sato, Manabu Nemoto, Yasuhiro Yamanaka
    JOURNAL OF AGRICULTURAL METEOROLOGY 70 1 25 - 40 2014年 [査読有り][通常論文]
     
    In Hokkaido, in northern Japan, rice yields are frequently affected by cool summers in the present climate. Recently, several studies have noted the possibility that cool summer damage may not be reduced even with global warming due to earlier rice phenology. We examined the changes in the range of rice sterility associated with rising temperatures focusing on inter-annual variation in temperature. By raising daily mean and daily maximum temperatures uniformly, we calculated the sterility rate of the Kirara397 variety locally planted in Hokkaido. Generally, long-term mean rice sterility decreases with rising temperatures. However, in each year and with each transplanting date, rice sterility remains identical to the present or even worsens in some cases. We called those cases "accelerated cool summer damage'' (ACSD). In the cases of rising temperature, the growth rate is accelerated, and the period of vulnerability to low temperatures become earlier. When the temperature during the earlier period of vulnerability is equal to or less than that during the original period of vulnerability in the present, ACSD occurs. Future rice sterility that induces cool summer damage may remain even if the temperatures rise associated with global warming, since the increase in temperature during the period of vulnerability is smaller than the range of inter-annual variation in temperature. We also found that there is a possibility that extremely high rice sterility is increased in a warmer climate if the range of inter-annual variation in temperature expands. This finding suggests that rice sterility may be increased by the inter-annual variation in temperature, even if the long-term mean sterility decreases as the temperature rises.
  • 中村一樹, 佐藤友徳
    寒地技術シンポジウム論文集 29 10 - 15 北海道開発技術センター 2013年11月 [査読有り][通常論文]
  • Tomonori Sato, Yongkang Xue
    Climate Dynamics 41 9-10 2411 - 2426 2013年11月 [査読有り][通常論文]
     
    Performance of a regional climate model (RCM), WRF, for downscaling East Asian summer season climate is investigated based on 11-summer integrations associated with different climate conditions with reanalysis data as the lateral boundary conditions. It is found that while the RCM is essentially unable to improve large-scale circulation patterns in the upper troposphere for most years, it is able to simulate better lower-level meridional moisture transport in the East Asian summer monsoon. For precipitation downscaling, the RCM produces more realistic magnitude of the interannual variation in most areas of East Asia than that in the reanalysis. Furthermore, the RCM significantly improves the spatial pattern of summer rainfall over dry inland areas and mountainous areas, such as Mongolia and the Tibetan Plateau. Meanwhile, it reduces the wet bias over southeast China. Over Mongolia, however, the performance of precipitation downscaling strongly depends on the year: the WRF is skillful for normal and wet years, but not for dry years, which suggests that land surface processes play an important role in downscaling ability. Over the dry area of North China, the WRF shows the worst performance. Additional sensitivity experiments testing land effects in downscaling suggest the initial soil moisture condition and representation of land surface processes with different schemes are sources of uncertainty for precipitation downscaling. Correction of initial soil moisture using the climatology dataset from GSWP-2 is a useful approach to robustly reducing wet bias in inland areas as well as to improve spatial distribution of precipitation. Despite the improvement on RCM downscaling, regional analyses reveal that accurate simulation of precipitation over East China, where the precipitation pattern is strongly influenced by the activity of the Meiyu/Baiu rainfall band, is difficult. Since the location of the rainfall band is closely associated with both lower-level meridional moisture transport and upper-level circulation structures, it is necessary to have realistic upper-air circulation patterns in the RCM as well as lower-level moisture transport in order to improve the circulation-associated convective rainfall band in East Asia. © 2012 Springer-Verlag Berlin Heidelberg.
  • Tomonori Sato, Shiori Sugimoto
    WATER RESOURCES RESEARCH 49 11 7763 - 7777 2013年11月 [査読有り][通常論文]
     
    The role of sea surface temperature (SST) anomaly in modulating the terrestrial precipitation in winter around Japan was investigated using a regional atmospheric model. Large amount of snowfall occurs as the westerly winter monsoon carries abundant moisture from the Japan Sea. An experiment with realistic SST gives improved representation of terrestrial precipitation distribution compared to the reanalysis. The standard deviation of interannual variation of precipitation in the experiment was approximately 20% larger over the Kuroshio extension than that in the experiment with climatology SST, suggesting that the SST variability enhances the oceanic precipitation variability. For the role of Japan Sea, the terrestrial precipitation over the Japan Sea side (JSS) region in northern Japan was sensitive to the offshore SST anomaly through affecting moisture flux toward Japan. Since the offshore SST was clearly warmer in the 2000s relative to the 1980s, the effect of the long-term SST variation on the terrestrial precipitation trend was examined. The experiment with realistic SST simulated the observed trend in terrestrial precipitation in the JSS region. In contrast, the precipitation trend was significantly reduced in the experiment with climatology SST. Therefore, the long-term SST trend is an important factor for the precipitation trend in the region of Japan and the adjacent oceans where SST has significant trends. Precipitation in southern Japan facing the Pacific Ocean indicated increasing trend even without the SST trend. This suggests that the long-term variations in extratropical cyclones are also an important factor for precipitation trends around the Kuroshio extension.
  • Tomonori Sato
    Monthly Weather Review 141 7 2451 - 2466 2013年 [査読有り][通常論文]
     
    Mesoscale processes that cause tremendous amounts of precipitation around the Meghalaya Plateau, northeast India, were investigated using a regional atmospheric model, with a particular focus on the possible role of an intraseasonal oscillation (ISO) and the diurnal cycle. A numerical experiment was conducted using the Weather Research and Forecasting Model (WRF) to simulate a prominent submonthly-scale ISO event observed during June-July 2004. A WRF experiment successfully simulated the timing and magnitude of precipitation during the first active period and subsequent inactive period of the ISO, despite large biases in the second active period. The WRF experiment revealed that the magnitude of prevailing southwesterly winds in the lower troposphere differs significantly between active and inactive periods strong southwesterly flow transports abundant moisture to the southern slope of the Meghalaya Plateau during the active period, which triggers forced lifting and brings orographic precipitation. However, low-level wind during the inactive period is too weak to overcome the vertical stratification barrier hence, it is unable to reach the condensation level. The WRF experiment suggested that the diurnal cycle of precipitation is enhanced during the active period, exhibiting an evening to early morning maximum, as observed by the Tropical Rainfall Measuring Mission (TRMM). The experiment also indicated a prominent nocturnal low-level jet (LLJ) appearing at 900 hPa. The direction of the LLJ varies clockwise with time, which accelerates the preexisting southwesterly flow during 1800-0600 LT. The diurnal variation of the LLJ is responsible for the evening to early morning maximum of precipitation, thus contributing to the precipitation variability in the ISO. © 2013 American Meteorological Society.
  • Shiori Sugimoto, Tomonori Sato, Kazuki Nakamura
    Journal of Applied Meteorology and Climatology 52 10 2226 - 2242 2013年 [査読有り][通常論文]
     
    In this study, long-term visibility data for the Pacific Ocean side of Hokkaido Island, northeast Japan, are investigated to clarify the relationship between interannual variation in summer fog frequency (FF) and largescale circulation patterns. At Kushiro, a significant FF decrease is found during 1931-2010 even without the influence of the observatory's relocation after 2000. In particular, since the late 1970s, a linear declining trend has accelerated, as evidenced by an increased number of years with very low FF in July and August. To clarify the climatological factor causing the summer FF declining trend at Kushiro, atmospheric vertical conditions in the planetary boundary layer and large-scale circulation are examined during 1989-2009 and 1958-2002, respectively, using available datasets. Composite analyses that are based on radiosonde observations reveal that the shallow fog layer is covered with a strong inversion layer during fog days whereas the inversion layer is absent during nonfog days. Composite circulation anomalies for the low-FF years at Kushiro show an intensified Okhotsk high (OH) pressure feature and southward shrinking of the North Pacific high (NPH) in July, in addition to the eastward displacement or shrinking of the NPH in August. These anomalous synoptic circulation patterns cause weakening in the southerly-southeasterly wind, which reduces sea-fog advection toward Kushiro and prevents the formation of stable stratification over the sea-fog layer. The authors suggest that the interannual variation in summer FF with the recent accelerated decline at Kushiro is primarily controlled by changes in the synoptic circulation associated with the OH and NPH development. © 2013 American Meteorological Society.
  • 田中朱美, 高橋潔, SHIN Yonghee, 増冨祐司, 山中康裕, 佐藤友徳
    地球環境研究論文集 20 I.237-I.248  2012年09月13日 [査読無し][通常論文]
  • Nobumitsu Tsunematsu, Hiroaki Kuze, Tomonori Sato, Masamitsu Hayasaki, Feifei Cui, Akihiko Kondoh
    ATMOSPHERIC ENVIRONMENT 45 37 6682 - 6695 2011年12月 [査読有り][通常論文]
     
    Spatial patterns of future atmospheric warming presented by climate model projections indicate that the temperatures of the lower troposphere will increase markedly at high latitudes in the Northern Hemisphere and also the upper troposphere at low-middle latitudes. In this study, potential impacts of the spatial patterns of future atmospheric warming on Asian dust emission were investigated by performing numerical experiments using a dynamical downscaling method. After three significant Asian dust outbreak events were reproduced as control runs, initial and boundary conditions of the control runs were updated by adding differences in atmospheric variables between the future climate (2091-2100) and the recent climate (1991-2000) to execute pseudo global warming runs. The results showed that the dust emission fluxes in the main Asian dust sources (MADSs), i.e., the Taklimakan and Gobi deserts, decrease markedly in the future climate condition. The future decreases in the dust emission fluxes are likely to be caused by a combination of the relatively large increases in sea level pressures (SLPs) in MADSs and the small SLP changes to the north of MADSs, which reduces the meridional SLP gradients between the two areas and consequently weakens cold air outbreaks. The large SLP increases in MADSs may be due to a northward shift of storm tracks and increased atmospheric stabilities caused by the large upper-tropospheric warming at low-middle latitudes. The small SLP changes to the north of MADSs corresponded to the large increases in surface air temperatures, which would be influenced by the large lower-tropospheric warming at high latitudes. (C) 2011 Elsevier Ltd. All rights reserved.
  • 中村一樹, 佐藤友徳, 山中康裕, 西村浩一
    寒地技術シンポジウム論文集, 2011 27 80 - 85 2011年 [査読無し][通常論文]
  • Altangerel Batbold, Tomonori Sato, Mamoru Ishikawa, Jamba Tsogt
    SOLA 7 117 - 120 2011年 [査読有り][通常論文]
     
    Global weather forecasts do not have sufficient performance to predict the local severe weather events that are accompanied with cyclones and cold fronts due to their coarse horizontal resolution. This study investigated the performance of dynamical downscaling (DD) using mesoscale model to simulate the severe windstorm in eastern Mongolia which occurred on 26-27 May 2008. Our results revealed that the DD experiments were successful in capturing the general features of the windstorm in terms of wind and temperature patterns. The timing and amplitude of drastic changes in the simulated temperature and wind speed were very similar to that observed than that obtained from the global atmospheric data, suggesting that DD is capable of predicting extreme wind storm events in Mongolia. Analyses on the nested domains indicate that the DD has crucial impact on the performance for simulating severe storm even with a moderate resolution (27 km), and further nesting (9 and 3 km) plays a role to improve it. Furthermore, the maximum wind speed approaches the observed value more closely as the horizontal resolution increases, although it still underestimates the observed wind speed even in the 3 km mesh domain. On the other hand, the abrupt temperature change is captured well even in the low-resolution domain, suggesting a difference in necessary horizontal resolution for temperature change and maximum wind speed.
  • Tomonori Sato, Akira Juri, Kei Masuyama, Eiji Imakita, Masahide Kimoto
    SOLA 7 169 - 172 2011年 [査読有り][通常論文]
     
    The downscaling framework, which is originally proposed by Emanuel et al. (2008), is modified to improve the interannual variation of the tropical cyclone features in Western North Pacific (WNP). The original framework, which utilizes axisymmetric model driven using monthly mean atmosphere and ocean variables, well reproduced interannual variation of tropical cyclone indices over North Atlantic while there is room for further improvement over WNP. The modified treatment of relative vorticity plays an essential role for improving interannual variation of genesis counts and power dissipation index in WNP. In this update, we introduced probability of cyclogenesis special to WNP which is a priori calculated using monthly mean 850-hPa level relative vorticity and best track. The result suggests that the monthly mean relative vorticity represents a potential of characteristic initiating disturbance in WNP such as monsoon trough and intraseasonal variation. Another experiment shows increased influence of vertical wind shear in middle troposphere improves the distribution of tropical cyclogenesis in WNP while it slightly deteriorates the interannual variation of genesis count.
  • Shinji Matsumura, Tomonori Sato
    SOLA 7 205 - 208 2011年 [査読有り][通常論文]
     
    Wintertime climate around Hokkaido is highly sensitive to fluctuations in snow and sea-ice. We examined future climate change in heavy snowfall region around Hokkaido, using the Pseudo-Global-Warming method (PGW) by a regional climate model. The boundary conditions of the PGW run were obtained by adding the difference between the future (2090s) and past (1990s) climates simulated by coupled general circulation models, into the 6-hourly reanalysis and daily sea surface temperature data. The PGW experiments show that snow depth decreases significantly over mountainous areas. However, snow cover decreases mainly over plain areas, which accelerates surface warming due to the decreased snow albedo. Despite the snow reductions, precipitation increases over the mountainous areas because of enhanced water vapor content. However, precipitation decreases over the Japan Sea and neighboring the coastal areas, suggesting a weakening of the convergent cloud band which is formed by convergence between cold northwesterly from the Eurasian continent and anticyclonic circulation over the Okhotsk Sea. Our results indicate the contrasting cloud responses to future climate change over the Japan and Okhotsk Seas in terms of meso-scale climate system.
  • Sato, Tomonori, Miura, Hiroaki, Satoh, Masaki, Takayabu, Yukari N., Wang, Yuqing
    JOURNAL OF CLIMATE 22 18 4809 - 4826 2009年09月 [査読有り][通常論文]
     
    This study analyzes the diurnal cycle of precipitation simulated in a global cloud-resolving model (GCRM) named the Nonhydrostatic Icosahedral Atmospheric Model (NICAM). A 30-day integration of NICAM successfully simulates the precipitation diurnal cycle associated with the land-sea breeze and the thermally induced topographic circulations as well as the horizontal propagation of diurnal cycle signals. The first harmonic of the diurnal cycle of precipitation in the 7-km run agrees well with that from satellite observations in its geographical distributions although its amplitude is slightly overestimated. The NICAM simulation revealed that the precipitation diurnal cycle over the Maritime Continent is strongly coupled with the land-sea breeze that controls the convergence/divergence pattern in the lower troposphere around the islands. The analysis also suggests that the cold pool often forms over the open ocean where the precipitation intensity is high, and the propagation of the cold pool events is related to the precipitation diurnal cycle as well as the land-sea breeze.Sensitivity experiments suggest a prominent horizontal resolution dependence of the simulated precipitation diurnal cycle. Over continental areas the 14-km run induces the diurnal peak about three hours later than the 7-km run. The 3.5-km run produces the peak time and amplitude that are very similar to those in Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) observations. Meanwhile, the resolution dependence in phase and amplitude is negligibly small over the open oceans. This contrast sensitivity to the horizontal resolution is attributed to the differences in structure and life cycle of convective systems over land and ocean.Diurnal peaks of precipitable water vapor, precipitation, and outgoing long wave radiation (OLR) are compared over land areas using the NICAM 7-km run. The daily precipitable water vapor maximum appears around 1500 local time (LT), which is followed by the precipitation peak around 1630 LT. The diurnal cycle of high clouds tends to peak around 1930 LT, three hours later than the precipitation peak. These results from NICAM simulations can explain the cause of the phase differences among precipitation products based on several satellite observations. The authors demonstrate that the GCRM is a promising tool for realistically simulating the precipitation diurnal cycle and could be quite useful for studying the role of the diurnal cycle in the climate systems in a global context.
  • Tomonori Sato
    QUATERNARY INTERNATIONAL 194 148 - 158 2009年02月 [査読有り][通常論文]
     
    Large topographic features, like the Tibetan Plateau (TP) and the Rocky Mountains, have significant impacts on Earth's climate. Numerical experiments were carried out using a regional climate model in order to study the sensitivity of rainfall distribution to the TP's thermal/dynamic effects and meridional position of the subtropical westerly jet. The sensitivity experiments under the present winter conditions, characterized by weaker solar radiation and westerly jet located to the south of the TP, reveal that broad and climate characterizes Northeast Asia, covering North China and Mongolia. The results are consistent with previous studies, indicating that TP dynamic forcing is dominant in winter. In sensitivity experiments under present summer conditions, characterized by stronger solar radiation and the westerly jet located to the north of TP, a prominent subsidence occurred over North China, where the Taklimakan and Gobi deserts are located. In summer, dynamic forcing of TP is very weak, whereas the thermal forcing of TP mainly induces subsidence. Relatively smaller mountain ranges, such as the TianShan Mountains, also modify the atmospheric circulation even during the summer season. The active convection zone along the Baiu front, which produces an elongate rain belt that extends from East China to Korea and Japan, is near the boundary of two moisture sources, transported by the westerly wind over the Eurasian continent and by the Asian summer monsoon flow. The millennial-scale variation in the location of the boundary reflects corresponding changes in East Asian climate, including monsoon intensity, storm activity, and the subtropical jet. (C) 2008 Elsevier Ltd and INQUA. All rights reserved.
  • Tomonori Sato, Takao Yoshikane, Masaki Satoh, Hiroaki Miltra, Hatsuki Fujinami
    JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 86A 17 - 31 2008年11月 [査読有り][通常論文]
     
    Sensitivity of precipitation diurnal cycle to the horizontal grid spacing was investigated using a mesoscale model without cumulus parameterization. Four numerical experiments with changing horizontal resolution are performed over one month with NCEP reanalysis boundary forcing. The studied range of grid spacing is from 3.5 km to 28 km which has been known as the intermediate scale to simulate mesoscale systems with/without cumulus parameterization. The target area is the Tibetan Plateau where pronounced diurnal cycle of convective systems is observed during the spring season. Lower resolution runs (14 and 28 km grid) show delayed formation and delayed mature stage of the cumulus convection in comparison to satellite observations. On the other hand, higher resolution runs (3.5 and 7 km grid) reproduce the proper development of the clouds after local noon which is consistent with observations. The total hydrometeor content and rainfall rate increase with grid size. Such systematic relationship of resolution dependencies are confirmed even in the monthly mean diurnal cycle, although most of previous studies examined only short periods. These results suggest that finer resolution at less than 7 kilometer is necessary to simulate realistic phase of the precipitation diurnal cycle over the Tibetan Plateau. The mechanism that is responsible for the resolution dependency is discussed. We suggest that the daytime convection which initially occurs due to unstable stratification over the Tibetan Plateau in spring tends to have a horizontal scale smaller than that is resolvable by the coarse resolution runs. ne delayed cloud formation induces larger downward shortwave radiation, which increases surface fluxes and results in too strong rainfall in the coarser resolution runs.
  • Hiroyuki Iwasaki, Tomonori Sato, Tomoki Nii, Fujio Kimura, Kiyotaka Nakagawa, Ichirow Kaihotsu, Toshio Koike
    MONTHLY WEATHER REVIEW 136 4 1401 - 1415 2008年04月 [査読有り][通常論文]
     
    The diurnal variations of convective activity and precipitable water were investigated using a C-band airport radar and GPS receivers around Ulaanbaator (UB), Mongolia; this location was considered as an example of an and region. The convective activity exhibited a pronounced diurnal cycle; it increased rapidly at 1100 local solar time (LST; 0300 UTC), reached the maximum at 1400 LST, and almost disappeared after 1900 LST. On the other hand, no diurnal variation of precipitable water could be observed, which implied that there was no considerable evapotranspiration, and the diurnal variation of the convective activity was irrelevant to the variation of water vapor. The reason why the deep convection could not develop at night is discussed using numerical modeling from the viewpoint of soil moisture. In the moist soil conditions assumed for humid simulations, an increase in the water vapor in the boundary layer due to evapotranspiration led to a potentially unstable condition that was sustained until night. Deep convection was formed at the southern foot of mountains where topographical convergence was expected. On the other hand, in the dry soil conditions assumed for the and simulations, deep convection did not occur during nighttime even though topographical convergence was expected over the southern foot of the mountains. These features of dry soil conditions were consistent with the results from radar observations around UB. In other words, since the soil around UB is too dry in practice to sustain an unstable condition until night, the deep convection had to decay by night and could not be initiated at night.
  • G. Li, F. Kimura, T. Sato, D. Huang
    THEORETICAL AND APPLIED CLIMATOLOGY 92 1-2 15 - 29 2008年03月 [査読有り][通常論文]
     
    The diurnal variations of water vapor in central Japan were investigated with GPS-derived precipitable water (PWV) and surface meteorological data as classified to three kinds of locations. Twenty-five clear days in central Japan in August 2000 were investigated to clarify the role of water vapor in the nocturnal maximum in the diurnal cycle of convective rainfall. The diurnal variations of PWV and some meteorological factors were composite during the selected days at 6 stations. The PWV shows a clear diurnal cycle with the amplitude of 3.4mm to 8.8mm and changes little during the period from the morning to noon. The daily amplitude of PWV is the largest in basin and smallest in plain although mean of PWV keeps high value in plain. A typical feature of the diurnal variation in central Japan is a maximum appearing in the evening. The time of maximum is from 1800 LST to 2000 LST, and minima appears at noon nearly in mountainous area and basin, while in early morning in plain. The diurnal maximum of PWV appears earlier in mountainous region than in plain. A diurnal cycle of specific humidity can be observed in all locations, and the amplitude in mountainous region is especially large compared with that in basin and plain. It is important to notice that there are remarkable differences in specific humidity among the six stations. The results suggest that the diurnal variation of PWV seems to be strongly affected by the local thermal circulations generated by the topography around these stations. The moisture transport causes the differences in phase of the diurnal cycle of PWV between different locations as well as the phase difference in precipitation. A very clear diurnal variation in surface air temperature is similar to that of solar radiation, with a minimum in the morning and a maximum in early afternoon. Maximum of surface wind speed are corresponded to peak of precipitation very well. It can be concluded that the amplitude of solar radiation increases with altitude as opposed to the situation of PWV generally. The precipitation observed frequently in the evening also shows a similar diurnal variation to that of the PWV, indicating the peak of precipitation appearing in late afternoon or in the evening over central Japan. Meanwhile the PWV reaches its nocturnal maximum. There is a good relationship between the diurnal cycle of observed precipitation and that of the PWV.
  • Fahu Chen, Zicheng Yu, Meilin Yang, Emi Ito, Sumin Wang, David B. Madsen, Xiaozhong Huang, Yan Zhao, Tomonori Sato, H. John B. Birks, Ian Boomer, Jianhui Chen, Chengbang An, Bernd Wuennemann
    QUATERNARY SCIENCE REVIEWS 27 3-4 351 - 364 2008年02月 [査読有り][通常論文]
     
    We synthesize palaeoclimate records from the mid-latitude arid Asian region dominated today by the Westerlies ("arid central Asia" (ACA)) to evaluate spatial and temporal patterns of moisture changes during the Holocene. Sediment records from I I takes with reliable chronologies and robust proxies were selected to reconstruct moisture histories based on a five-class ordinal wetness index with assigned scores from the driest to wettest periods at individual sites for 200-year time slices. The proxies used in these records include pollen and diatom assemblages, sediment lithology, lake levels, and geochemistry (mainly isotope) data. The results of our synthesis show that ACA as a whole experienced synchronous and coherent moisture changes during the Holocene, namely a dry early Holocene, a wetter (less dry) early to mid-Holocene, and a moderately wet late Holocene. During the early Holocene most of the lakes experienced very low water levels and even dried out before ca 8 ka (1 ka = 1000cal a BP). Hence the effective-moisture history in ACA is out-of-phase with that in monsoonal Asia as documented by numerous palaeoclimate records. In monsoonal Asia, a strong summer monsoon and humid climate characterized the early Holocene, and a weakened summer monsoon and drier climate prevailed during the late Holocene, which were mainly controlled by changes in low-latitude summer insolation. In contrast, we propose that the pattern of Holocene effective-moisture evolution in the westerly dominated ACA was mainly determined by North Atlantic sea-surface temperatures (SSTs) and high-latitude air temperatures that affect the availability, amount and transport of water vapor. Also, topography of the Tibetan Plateau and adjacent Asian highlands could have contributed to the intensification of dry climate in ACA during the early Holocene, as a result of strengthening the subsidence of dry air masses, associated with stronger uplift motion on the plateau by intense heating under a stronger summer insolation. Summer insolation might have played a key role in directly controlling moisture conditions in ACA but only after the northern hemisphere ice-sheets had disappeared in the mid- and late Holocene. (C) 2007 Elsevier Ltd. All rights reserved.
  • Hiroaki Kawase, Takao Yoshikane, Masayuki Hara, Fujio Kimura, Tomonori Sato, Shingo Ohsawa
    GEOPHYSICAL RESEARCH LETTERS 35 1 6  2008年01月 [査読有り][通常論文]
     
    Irrigated farmland in an arid region creates a prominent heat contrast along its boundary. A statistical analysis of satellite images indicated that the frequency distribution of clouds has a clear contrast between the Hetao Irrigation District in China and the surrounding dry area in the summer. In this paper, we use a mesoscale model to clarify the impact of the extensive irrigation on the cloud formation. The numerical experiment assuming simplified irrigation indicates that the colder surface of the irrigated area induces a surface wind toward the dry area, where the surface temperature is higher. This wind is a part of a land-use-induced circulation. The circulation matures in the early afternoon and generates clouds near the border of the dry area and irrigated area.
  • Tomonori Sato, Fujio Kimura, Akira S. Hasegawa
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 D24 2007年12月 [査読有り][通常論文]
     
    [1] Cloud patterns over arid/semi-arid area in the Northeast Asia are investigated by statistical analysis of the satellite observations in relation to the roles of topography and vegetation contrasts. In the morning, cloud frequencies are high over the mountainous areas in the northern Mongolia. In the afternoon and early evening, the frequencies increase in the entire analyzed domain. The frequencies are prominently enhanced over the slopes and mountains. The upslope wind prevails during the daytime where vegetation contrasts are not sharp or the slope is steep, even though vegetation covers the mountain which tends to cool the mountain slope. The land- cover- induced cloud formations are distinctly observed where the slope is gentle and vegetation contrast is sharp enough to form a prominent surface temperature contrast. Around the Yellow River, the cloud frequency rapidly increases in the afternoon due to the vegetation contrast, whereas it remains very low over the river. We hypothesized that the smaller sensible heat flux from the vegetated surface suppresses the development of the daytime mixed layer. Thus the cumulus clouds near top of the mixed layer are difficult to form. It is inferred from the statistical analysis that the afforestation of the desertified lands may cause the decrease of cloud frequency above it.
  • Sato, Tomonori, Miura, Hiroaki, Satoh, Masaki
    GEOPHYSICAL RESEARCH LETTERS 34 18 6  2007年09月 [査読有り][通常論文]
     
    Thermal forcing of the Tibetan Plateau (TP) has large impacts on the Asian summer monsoon. In this study, we statistically analyzed the outputs from the global cloud- resolving model, NICAM (Nonhydrostatic ICosahedral Atmospheric Model). In order to investigate the convective activities, two brightness temperature datasets were compared, one derived from the satellite observation and another derived from the model. The model well simulated the spatio- temporal variations of convective clouds in April 2004. The diurnal cycle of clouds was better represented in NICAM, which shows only few- hour phase difference, than that in the reanalysis data. Three experiments changing horizontal resolution revealed that the higher resolution run conducts better representation of the diurnal cycle, especially on the nighttime disappearance of the high clouds. These results indicate that the global cloud- resolving model will improve the seasonal prediction of the Asian summer monsoon through better description on the thermal forcing of the Tibetan Plateau.
  • Tomonori Sato, Maki Tsujimura, Tsutomu Yamanaka, Hiroyuki Iwasaki, Atsuko Sugimoto, Michiaki Sugita, Fujio Kimura, Gombo Davaa, Dambaravjaa Oyunbaatar
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 D17 D17112?D17112-13  2007年09月 [査読有り][通常論文]
     
    Origin of water vapor, which falls as precipitation over arid/ semiarid area in northeast Asia, is investigated by modeling and observational approaches. The regional climate model evaluates the spatiotemporal variations of precipitation and water vapor budget, which are used to drive the single- layer isotope circulation model. Intraseasonal variations of delta(18) O in precipitation are well simulated during June- July- August of 2003. The delta(18) O in water vapor experiences rapid decreases according to the passage of synoptic- scale disturbances. The rapid decreases of delta(18) O are attributed to two processes. ( 1) The delta(18) O in air mass locally decreases over the western mountains associated with the mountain precipitation; the light vapor is advected to eastern Mongolia by the prevailing westerly wind. ( 2) Convective systems pass by in the vicinity of the observation site, which persistently keep the lower delta(18) O in the air mass. Origin of the water vapor during June-July- August in 2003 is evaluated by the colored moisture analysis in which the tracers are assigned depending on the region where the water vapor finally evaporated. Seasonal mean result indicates that the regions contributing to precipitation in Mongolia are not low- latitude regions but central Asia and western Siberia located to the northwest of Mongolia. Observed multilevel isotopic composition supports the model estimation. The moisture transport along the southwesterly wind of the Asian summer monsoon has difficulty reaching Mongolia as a monthly/ seasonal mean perspective. However, eastern Mongolia and northeast China are situated on the border area between westerly wind moisture transport ( by midlatitude synoptic cyclones) and southerly wind moisture transport ( by Asian summer monsoon).
  • SATO T., TSUJIMURA M., YAMANAKA T., KIMURA F., IWASAKI H., SUGIMOTO A., SUGITA M., DAVAA G., OYUNBAATAR D., NII T., NAKAGAWA K., KAIHOTSU I., KOIKE T.
    筑波大学陸域環境研究センター報告, 北東アジア植生変遷域の水循環と生物・大気圏の相互作用 : RAISEプロジェクトで何が分かったか = Bulletin of the Terrestrial Environment Research Center, the University of Tsukuba, Rangelands Atmosphere-Hydrosphere-Biosphere Interaction Study Experiment in Northeastern Asia : Highlights of the RAISE Project 8 75 - 79 筑波大学陸域環境研究センター 2007年08月 
    Where does precipitation water comes from? ......75The break in Mongolian rainy season and the relation with the stationary Rossby wave along the Asian jet ......76Study on influence of rainfall distribution on NDVI anomaly over the arid regions in Mongolia using an operational weather radar ......77Diurnal variation of convective activity and precipitable water around Ulaanbaator, and impact of soil moisture on convective activity in the nighttime ......78
  • 佐藤 友徳, 辻村 真貴, 山中 勤, 木村 富士男, 岩崎 博之, 杉本 敦子, 杉田 倫明, ダワー ゴンボ, オユンバータル ダムバラブジャー, 新居 知巳, 中川 清隆, 開發 一郎, 小池 俊雄
    筑波大学陸域環境研究センター報告, 北東アジア植生変遷域の水循環と生物・大気圏の相互作用 : RAISEプロジェクトで何が分かったか = Bulletin of the Terrestrial Environment Research Center, the University of Tsukuba, Rangelands Atmosphere-Hydrosphere-Biosphere Interaction Study Experiment in Northeastern Asia : Highlights of the RAISE Project 8 4 - 8 筑波大学陸域環境研究センター 2007年08月 
    モンゴルの雨はどこからやってくるのか？ ……4モンゴルにおける雨期の中休みとアジアジェットに沿った定在ロスビー波との関係 ……5空港レーダーを用いた降水量分布がモンゴルのNDVI偏差分布に及ぼす影響についての研究 ……6ウランバートル周辺の対流活動度と可降水量の日変化、及び、土壌水分量が夜間の対流活動度に与える影響 ……7
  • 佐藤 友徳, 木村 富士男, 陳 玉香, 李 吉宰, 李 弼宰, 及川 武久, 李 勝功, 浦野 忠朗, 杉田 倫明
    筑波大学陸域環境研究センター報告, 北東アジア植生変遷域の水循環と生物・大気圏の相互作用 : RAISEプロジェクトで何が分かったか = Bulletin of the Terrestrial Environment Research Center, the University of Tsukuba, Rangelands Atmosphere-Hydrosphere-Biosphere Interaction Study Experiment in Northeastern Asia : Highlights of the RAISE Project 8 29 - 32 筑波大学陸域環境研究センター 2007年08月 
    地球温暖化によりモンゴルの降水はどうなるか？ ……29モンゴル草原生態系の地上部バイオマスと純一次生産への放牧の影響 ……30モンゴル草原生態系における放牧への植物根の応答 ……31モンゴル草原生態系を対象とした炭素/水動態の推定と未来予測 ……32
  • Tomonori Sato, Fujio Kimura
    MONTHLY WEATHER REVIEW 135 5 2006 - 2015 2007年05月 [査読有り][通常論文]
     
    The roles of the Tibetan Plateau (TP) upon the transition of precipitation in the south Asian summer monsoon are investigated using a simplified regional climate model. Before the onset of the south Asian monsoon, descending flow in the midtroposphere, which can be considered as a suppressor against precipitation, prevails over northern India as revealed by the NCEP-NCAR reanalysis data. The descending motion gradually weakens and retreats from this region before July, consistent with the northwestward migration of the monsoon rainfall. To examine a hypothesis that the dynamical and thermal effects of TP cause the midtropospheric subsidence and its seasonal variation, a series of numerical experiments are conducted using a simplified regional climate model. The mechanical effect of the TP generates robust descending flow over northern India during winter and spring when the zonal westerly flow is relatively strong, but the effect becomes weaker after April as the westerly flow tends to be weaker. The thermal effect of the TP, contrastingly, enhances the descending flow over north India in the premonsoonal season. The descending flow enhanced by the thermal effect of the TP has a seasonal cycle because the global-scale upper-level westerly changes the energy propagation of the thermal forcing response. The subsidence formed by the mechanical and thermal effects of the TP disappears over northern India after the subtropical westerly shifts north of the plateau, the seasonal change of which is in good agreement with that in the reanalysis data. The retreat of the descending flow can be regarded as the withdrawal of the premonsoon season and the commencement of the south Asian monsoon. After that, the deep convection, indicating the onset of the Indian summer monsoon, is able to develop over north India in relation to the ocean atmosphere and land-atmosphere interaction processes. Northwest India is known to be the latest region of summer monsoon onset in south Asia. Thus, the thermal and mechanical forcing of the TP has great impact on the transition of the Indian monsoon rainfall by changing the midtropospheric circulation.
  • Tomonori Sato, Fujio Kimura, Akio Kitoh
    JOURNAL OF HYDROLOGY 333 1 144 - 154 2007年01月 [査読有り][通常論文]
     
    Climate change due to global warming is of concern to the public and may cause significant changes in the hydrological regimes in arid/semi-arid areas including Mongolia, which locates at a boundary between and and humid regions. However, general circulation models (GCMs) are not sufficient to evaluate climate change on a regional-scale. In this study, two kinds of dynamical downscaling (DDS), referred to as method-G and method-R, using a regional climate model (RCM) are applied to investigate the rainfall change over Mongolia in July due to the global warming. Method-G is a traditional DDS method in which an RCM is directly nested within a GCM, while method-R is newly suggested in this study and aims to improve the reproductivity of a regional climate. For current climate simulation, method-R uses reanalysis data as a boundary forcing of the RCM while a specialty created boundary condition, in which projected changes of meteorological variables in a GCM simulation are added on reanalysis data, is used for global warming simulation. Compared with in situ observations, the rainfall amount for July is very well reproduced by the RCM, even in a smatter area of four subregions in Mongolia. Rainfall intensity by method-R is very close to actual observations; on the other hand, method-G fails to simulate heavy rainfall events stronger than 16 mm day(-1). The two DDS methods show similar results with respect to the changes of precipitation in July due to the global warming, which are that precipitation decreases over northern and increases over southern Mongolia. In method-R, a decrease of precipitation of middle to heavy rainfall intensity, stronger than 4 mm day', contributes largely to the decreased July precipitation in northern Mongolia. Soil moisture over Mongolia also tends to decrease in July because of the combined effect caused by the decrease of precipitation and the increase of potential evaporation due to rising air temperature. This situation indicates that severe droughts may occur more frequently from the effects of global warming. (c) 2006 Elsevier B.V. All rights reserved.
  • Hiroaki Kawase, Yoshitaka Takeuchi, Tomonori Sato, Fujio Kimura
    SOLA 2 25 - 28 2006年 [査読無し][通常論文]
     
    During the winter monsoon, a convergence line called the Boso Front often appears in the area between the Kanto Plain and the Izu Islands, Japan. Two typical cases of high-level Precipitable Water Vapor (PWV) are observed along the convergence line in the lee of Chubu Mountains by the aid of latest techniques of Global Positioning System (GPS). Statistic analysis of GPS derived Precipitable Water Vapor (GPS-PWV) indicates that the prevailing wind direction controls the position of the high-level PWV in the lee of Chubu Mountains. A numerical model simulates the behavior of water vapor, namely, the temporal variation of simulated PWV and surface wind, which suggest the reasons for the high PWV near the convergence line. The convergence of surface wind gathers moisture, and trapped moisture by reduced wind velocity may also contribute the high-level PWV.
  • N Tsunematsu, T Sato, F Kimura, K Kai, Y Kurosaki, T Nagai, HF Zhou, M Mikami
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 110 D21 12  2005年11月 [査読有り][通常論文]
     
    [1] Extensive dust outbreaks occurred on the late morning of 26 March 2004 in the Taklimakan Desert. An image by the satellite AQUA shows the dust outbreaks as an enormous dust storm extending as far as 1000 km in the direction of east and west across the desert. A ground-based lidar was successful in observing the dust storm. Values of the backscattering ratio from near the ground surface to an altitude of 6 km above sea level rapidly increased as soon as the dust storm covered the lidar observation site. Numerical experiments including a diffusion experiment revealed that strong westerly winds appeared at the surface level following the morning inversion breakup and then induced the dust outbreaks. The nocturnal inversion layer prevented the strong westerly winds from spreading to the surface level until the breakup. Notable nocturnal inversion is considered to be easily formed in the Taklimakan Desert because of its deep basin topography which can accumulate cold air masses. These results show the stability of the planetary boundary layer to be an extremely important factor in dust outbreaks especially in basin deserts, in addition to the intensity of surface winds. This implies that the occurrence frequency of dust storms in the desert has a diurnal cycle.
  • T Sato, F Kimura
    JOURNAL OF THE ATMOSPHERIC SCIENCES 62 5 1626 - 1636 2005年05月 [査読有り][通常論文]
     
    Convective rainfall often shows a clear diurnal cycle. The nighttime peak of convective activity prevails in various regions near the world's mountains. The influence of the water vapor and convective instability upon nocturnal precipitation is investigated using a numerical model and observed data. Recent developments in GPS meteorology allow the estimation of precipitable water vapor (PWV) with a high temporal resolution. A dense network has been established in Japan. The GPS analysis in August 2000 provides the following results: In the early evening, a high-GPS-PWV region forms over mountainous areas because of the convergence of low-level moisture, which gradually propagates toward the adjacent plain before midnight. A region of convection propagates simultaneously eastward into the plain. The precipitating frequency correlates fairly well with the GPS-PWV and attains a maximum value at night over the plain. The model also provides similar characteristics in the diurnal cycles of rainfall and high PWV. Abundant moisture accumulates over the mountainous areas in the afternoon and then advects continuously toward the plain by the ambient wind. The specific humidity greatly increases at about the 800-hPa level over the plain at night, and the PWV reaches its nocturnal maximum. The increase in the specific humidity causes an increase of equivalent potential temperature at about the 800-hPa level: as a result. the convective instability index becomes more unstable over the plain at night. These findings are consistent with the diurnal cycle of the observed precipitating frequency.
  • Aoki, I, Y Kurosaki, R Osada, T Sato, F Kimura
    GEOPHYSICAL RESEARCH LETTERS 32 6 4  2005年03月 [査読有り][通常論文]
     
    By the numerical experiments, we clarify the regional wind systems that generate dust storms in the Tarim basin, Northwest China. In the basin, dust storms are generated by a mesoscale cold wind system induced by a synoptic-scale cold air mass behind a cold front. The intruding course of the mesoscale cold wind into the basin can be classified into three patterns. The first pattern is characterized by the easterly mesoscale cold wind, which is separated from the synoptic- scale cold westerly and turns westward after going around the eastern side of the TianShan Mountains. The mesoscale cold wind categorized in the second pattern directly crosses over the TianShan Mountains, which often gives a very strong wind in the basin with the largest dust storms in the three patterns. The third pattern indicates that the cold wind crosses over Pamir plateau, although the magnitude of the dust storm is usually small.
  • T Sato
    GEOPHYSICAL RESEARCH LETTERS 32 5 L05809.1-L05809.5  2005年03月 [査読有り][通常論文]
     
    [1] The formation mechanism of the arid climate over northeast Asia is investigated by a series of regional climate model experiments. Precipitation there is suppressed by a prominent regional-scale subsidence during summertime. An experiment without diabatic heating shows very gentle vertical motion there, whereas the subsidence is prominent when diabatic heating by solar radiation is included in the model. Additionally, the other experiments indicate that an artificial heating over the Tibetan Plateau enhances the subsidence over the arid area which is similar to the observed distribution. These results suggest that the thermal effects of the plateau induce the prominent subsidence. The mechanical effects of the topography, such as stationary mountain waves, are not a principal reason for the subsidence nor the arid climate. The stationary Rossby wave driven by the diabatic heating over the plateau tends to propagate northward during boreal summer, since subtropical westerly jet locates north of the plateau.
  • Tomonori Sato
    SOLA 1 13 - 16 2005年 [査読無し][通常論文]
     
    The role of mountain ranges upon the arid climate formation in northwestern China is investigated using regional climate model. Two kinds of numerical experiments are carried out with real topography and with modified topography which does not contain the TianShan Mountains. Simulated rainfall distribution with real topography shows maximum precipitation in upwind slope of the mountain and minimum precipitation in downwind side of it, which coincides with the features of rain-shadow in other regions of the world. However, numerical experiment without the TianShan Mountains also simulates the area of distinct minimum precipitation in the same location. The arid climate, therefore, is formed even though the rain shadow effect is absent. The difference in rainfall amount between these two experiments is very small around downwind arid region. On the other hand, more intense and frequent rainfall events tend to occur in upwind of the mountain range due to forced lifting of environmental flow, which just emphasizes the precipitation contrast between upwind and downwind side of the mountain. The precipitation accompanied with the synoptic scale disturbances is suppressed over the arid region whether the TianShan Mountains exist or not.
  • Kawase Hiroaki, Sato Tomonori, Kimura Fujio
    GEOPHYSICAL RESEARCH LETTERS 32 3 147 - 159 The Association of Japanese Geographers 2005年 [査読有り][通常論文]
     
    冬季北西風の吹出し時に,日本の周辺海域には筋状雲が現われる.その中でも,日本の南海上ではしばしば太い筋状雲が発生する.本研究では,冬季3カ月(1, 2, 12月)のGMS (Geostationary Meteorological Satellite)可視画像を分析し,850hPaの風と対応させることで,このような筋状雲が下層風によって受ける影響を調べた.その結果,筋状雲の出現は風向だけでなく風速によっても変化することがわかった.筋状雲には風速の増加に伴い発生頻度が増加するものと,逆に発生頻度が減少するものが存在する.九州の東海上,四国の南海上に現れる筋状雲は前者にあたり,紀伊山地の風下,紀伊水道で発生している筋状雲が後者にあたる.また,風速の変化によって出現する位置が変化する筋状雲も存在する.四国山地の南東風下にできる筋状雲がこれにあたり, 850hPaの風速が増加するほど発生位置が北東に移動する.
  • 佐藤 友徳
    天気 51 3 161 - 162 社団法人日本気象学会 2004年03月31日 [査読有り][通常論文]
  • T Sato, F Kimura
    JOURNAL OF THE ATMOSPHERIC SCIENCES 60 16 1992 - 2003 2003年08月 [査読有り][通常論文]
     
    Simple numerical experiments using a two-dimensional model were conducted to investigate the diurnal variation of water vapor in the lee of a mountain range, which strongly affects nighttime precipitation. In the daytime, moisture increases around the convergence zone in the lee of the mountain were formed by thermally induced local circulations in moderate ambient wind. Then, a region of enhanced precipitable water vapor (PWV) was formed. The region of enhanced PWV was transported to the lee side of the mountain by the ambient wind and finally reached the plain during the night. The convective instability in the lower troposphere and the possibility of deep convection were controlled by the advection of water vapor in the lee of the mountain, especially by the position of the enhanced PWV region. As a result, the diurnal cycle of the convective instability showed a phase difference between the mountainous region and the plain. The profile of equivalent potential temperature tended to be unstable in the lee of the mountain at night and contributed to the production of nighttime precipitation. The propagation speed of the enhanced PWV region was roughly determined by the ambient wind speed. Some sensitivity experiments using bulk microphysics have suggested that the propagation speed of the enhanced PWV region is insensitive to the occurrence of a deep convection. The enhanced PWV region generated over a wider mountain range tends to travel farther, retaining its magnitude even until night. The water vapor transport process presented in this study agrees well with the actual diurnal variations of rainfall observed in many regions over land.

書籍

  • ロシア文化事典
    沼野充義, 望月哲男, 池田嘉郎編集, 佐藤友徳他 (担当:共著範囲:気候・気象)
    丸善出版 2019年
  • 日本気候百科
    佐藤 友徳 (担当:分担執筆範囲:北海道の気候)
    丸善出版 2018年01月
  • Global cloud/cloud-resolving models and the Madden-Julian Oscillation
    Miyakawa, T, T. Sato 
    World Scientific Publishing 2016年 385 173-184
  • 北半球寒冷圏陸域の気候・環境変動
    飯島慈裕, 佐藤友徳 (担当:編者(編著者))
    2014年10月
  • 高緯度における大気−陸面相互作用
    佐藤友徳 
    2014年 178-195
  • Cloud-cluster-resolving global atmospheric modeling -A Challenge for the new age of tropical meteorology
    Matsuno, T, M. Satoh, H. Tomita, T. Nasuno, S.-I. Iga, A. T. Noda, K. Oouchi, T. Sato, W. Yanase, H. Miura, H. Fudeyasu 
    World Scientific Publishing Co. 2011年 455-473

講演・口頭発表等

  • ユーラシア大陸における夏季気温偏差場の予測可能性に対する陸面の寄与  [通常講演]
    佐藤友徳, 中村哲
    日本気象学会2018年春季大会 2018年05月 口頭発表（一般）
  • Investigating a possible contribution of land surface processes on extreme hot event in Northeast Eurasia in recent summer  [通常講演]
    Sato, T, E. Erdenebat, T. Nakamura
    8th GEWEX Open Science Conference 2018年05月 口頭発表（一般）
  • アンサンブル気候予測データを用いた日本周辺における月降水量極端事象の将来変化  [通常講演]
    初塚大輔, 佐藤友徳
    日本気象学会2017年秋季大会 2017年10月 ポスター発表
  • 北東ユーラシアにおける大気-陸面相互作用−特に暖候期の水循環に関連して−  [通常講演]
    佐藤友徳
    日本気象学会2017年秋季大会(統合的陸域圏研究連絡会) 2017年10月 口頭発表（一般）
  • アンサンブル気候予測データを用いた日本周辺における台風通過頻度の将来変化に関する要因解析  [通常講演]
    松下侑未, 佐藤友徳
    日本気象学会2017年秋季大会 2017年10月 口頭発表（一般）
  • 北海道西岸沖で発生する小低気圧に対する海氷および山岳の効果  [通常講演]
    佐藤友徳, 田村健太
    雪氷研究大会2017 2017年09月 口頭発表（一般）
  • How strongly is polar low genesis around North Japan influenced by Earth surface forcings?  [通常講演]
    Sato T, K. Tamura
    2016 AGU Fall meeting 2016年12月 ポスター発表
  • 過去の地域気候変化に対する下部境界条件の寄与  [招待講演]
    佐藤友徳, 田村健太, 中村誠吾, 杉本志織
    メソ気象研究会 2016年10月 口頭発表（招待・特別）
  • Diurnal variation of precipitation around the Meghalaya Plateau during the break phase of sub-monthly intraseasonal oscillation  [通常講演]
    Sato, T, and T, Ichigi
    International workshop on land surface multi-spheres processes of Tibetan Plateau 2016年08月 口頭発表（一般）
  • Role of snow cover on urban heat island intensity investigated by urban canopy model with snow effects  [通常講演]
    Tomonori Sato, Keisuke Mori
    AGU Fall meeting 2015 2015年12月 口頭発表（一般）
  • Seasonally and diurnally different response of surface air temperature to historical urbanization in Sapporo, North Japan  [通常講演]
    Sato, T, S. Sugimoto, T. Sasaki
    AGU fall meeting 2014 2015年12月 ポスター発表
  • 東京に降雪をもたらす低気圧の経路と黒潮流路変動の関係についての統計解析  [通常講演]
    天澤俊行, 佐藤友徳
    日本気象学会2015年春季大会 2015年05月 口頭発表（一般）
  • マルチGCM×マルチRAMの気候データを用いたてん菜糖量の将来変化予測  [通常講演]
    友貞俊成, 佐藤友徳
    日本農業気象学会全国大会 2015年03月 口頭発表（一般）
  • Coherent variability between diurnal cycle and intraseasonal oscillation in orographic precipitation around the Meghalaya Plateau  [通常講演]
    Sato, T
    7th International Scientific Conference on the Global Water and Energy Cycle (GEWEX） 2014年 口頭発表（一般）
  • A modeling study on the role of local SST warming on the precipitation trends observed in north Japan during winter monsoon  [通常講演]
    Sato, T, S. Sugimoto
    AGU Fall meeting 2013 2013年12月 ポスター発表
  • 日本海海面水温の上昇と冬季降水量の長期変化傾向について  [通常講演]
    佐藤友徳, 杉本志織
    日本気象学会2013年秋季大会 2013年11月 口頭発表（一般）
  • Possible impact of sea surface warming on the spatial variation of winter precipitation trends in north Japan  [通常講演]
    Sato, T, S. Sugimoto
    Davos Atmosphere and Cryosphere Assembly DACA-13 2013年07月 口頭発表（一般）
  • 季節内振動によるメガラヤの降水極大と日変化  [通常講演]
    佐藤友徳
    日本気象学会2013年春季大会 2013年05月 口頭発表（一般）
  • 地域スケールの気候予測情報とその活用  [通常講演]
    佐藤友徳
    日本気象学会2012年秋季大会一般公開シンポジウム「気象学が地域の未来にいかに貢献できるか？これからの北海道の地域づくりと気象学の研究」 2012年10月 シンポジウム・ワークショップパネル（公募）
  • Assessment of dynamical downscale ability to simulate intra-seasonal and interannual variation in East Asia  [通常講演]
    Sato, T, Y. Xue
    AMS 2011annual meeting 2011年 ポスター発表
  • Assessment of dynamical downscale ability to simulate intra-seasonal variation in China and Mongolia  [通常講演]
    Sato, T, Y. Xue
    10th International Regional Spectral Model Workshop 2010年08月 シンポジウム・ワークショップパネル（公募）
  • 熱帯低気圧の気候変動に伴う変化 -低解像度環境場からの推定-  [通常講演]
    重里 昌, 増山 啓, 佐藤 友徳, 三浦 裕亮, 末吉 哲雄, 木本 昌秀
    日本気象学会2010年秋季大会 2010年 ポスター発表
  • 中国東部およびモンゴルにおける地域気候モデルの降水再現性の検証  [通常講演]
    佐藤友徳, Y. Xue
    日本気象学会2010年秋季大会 2010年 口頭発表（一般）
  • Influences of global warming and local processes on warm season climate in Mongolia  [通常講演]
    Sato, T, F. Kimura
    MOCA-09 (IAMAS/IAPSO/IACS Joint Assembly) 2009年07月 口頭発表（一般）
  • Role of cold pool formation on the diurnal cycle of precipitation over the maritime continent  [通常講演]
    Sato, T, H. Miura, M. Satoh, Y. N. Takayabu
    International MAHASRI/HyARC workshop on Asian monsoon and Water cycle 2009年03月 シンポジウム・ワークショップパネル（公募）
  • 北東アジアにおける夏季の降水起源の年々変動について  [通常講演]
    佐藤友徳
    日本気象学会2009年秋季大会 2009年 口頭発表（一般）
  • 地球温暖化による黄砂発生ポテンシャル変化の検証  [通常講演]
    佐藤友徳, 木本昌秀
    日本気象学会2008年春季大会 2008年 ポスター発表
  • 全球雲解像モデルNICAMによる熱帯域の降水日変化と解像度依存性  [通常講演]
    佐藤友徳, 三浦裕亮, 佐藤正樹, 高藪縁
    日本気象学会2008年春季大会 2008年 口頭発表（一般）
  • Diurnal convective activity over Tibetan plateau in the global cloud-resolving model, NICAM  [通常講演]
    Sato, T, H. Miura, M. Satoh
    XXIV IUGG General Assembly 2007年 口頭発表（一般）
  • 関東地方南部における降水系の強化と都市の関係  [通常講演]
    佐藤友徳, 寺島司, 井上忠雄, 木村富士男
    日本気象学会2006年春季大会 2006年 口頭発表（一般）
  • Numerical study on the arid climate formation in middle latitude Asia  [招待講演]
    Sato, T
    RACHAD 2006 workshop 2006年 口頭発表（招待・特別）
  • Role of mountains on the formation of the arid climate in northwestern China  [通常講演]
    Sato, T, F. Kimura
    IAMAS 2005 scientific assembly 2005年 口頭発表（一般）
  • Diurnal cycle of precipitable water vapor and convective instability around the central mountains in Japan during August 2000  [通常講演]
    Sato, T, F. Kimura
    IAMAS 2005 scientific assembly 2005年 口頭発表（一般）
  • 領域気候モデルを用いたモンゴル東部における大気水収支解析  [通常講演]
    佐藤友徳, 辻村真貴, 木村富士男, 佐々木リサ, 杉本敦子, 山中勤
    地球惑星科学関連学会2004年合同大会 2004年 口頭発表（一般）
  • 一般風と山谷風による水蒸気輸送の２次元数値シミュレーション  [通常講演]
    佐藤友徳, 木村富士男
    2001年日本気象学会春季大会 2001年 口頭発表（一般）

その他活動・業績

共同研究・競争的資金等の研究課題

  • 気象気候の遠隔影響と予測可能性: 陸域プロセスを介した気象・気候変動の理解
    文部科学省：北極域研究加速プロジェクト(ArCS2)
    研究期間 : 2020年06月 -2025年03月
  • 日本学術振興会：科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2019年06月 -2024年03月 
    代表者 : 飯塚 聡, 万田 敦昌, 佐藤 友徳, 川瀬 宏明, 安永 数明, 美山 透
     
    日本近海の水温変化傾向に関する知見をさらに進化させるため，高分解能海洋再解析データを活用して1993年以降の海洋熱波のデータセットを作成した。このデータセットの解析を行った結果，海洋熱波が2015年以降急増していること，さらに水温上昇は海面付近に限定されるものではなく，その鉛直方向の広がりは海面下数百メールにも及ぶことが明らかとなった。また，日本近海の長期的な温暖化傾向が，平成29年7月九州北部豪雨に対してどのような影響を与えていたのかを数値実験によって評価した。その結果，熱帯でみられるような気温上昇に伴う水蒸気量の増加よりも，むしろ中緯度海洋からの加湿によって生じた不安定化に伴う対流システムの上昇流強化を通じて降水量に影響を与えることがわかった。 日本近海の水温の長期変化が極端気象にもたらす影響に関する知見を一般化する目的で，アンサンブル気候予測データベース（d4PDF）を用いて，強雨をもたらす総観場毎に強雨頻度と海面水温との関係を調べた。その結果，上空寒気や強い水蒸気移流を伴う総観場において，近海の海面水温が高いほど強雨の頻度が増加することが分かった。この他，日本周辺海域に特有な黒潮大蛇行に着目し，それに伴う海面水温が豪雨などに及ぼす影響について調べた。 日本海の暖候期の降水粒子の特性に関する観測では，雨粒の大きさと数密度の特徴に着目した解析を新規に行い、暖候期に冷たい雨と暖かい雨と呼ばれる異なる降水過程が起きていることを示唆する観測事実を捉えることができた。A02-3班が中心に実施した日本海寒帯気団収束帯(JPCZ)の船舶観測の地上支援を実施するとともに，領域モデルによる再現実験も行うことで班間連携をさらに強化した。豪雪事例として，令和2年度の記録的豪雪に加え，2018年1月に新潟市で発生した大雪に対する海面水温の影響を調べる研究も進めた。
  • 日本学術振興会：科学研究費助成事業 基盤研究(S)
    研究期間 : 2019年06月 -2024年03月 
    代表者 : 平野 高司, 谷 晃, 伊藤 雅之, 林 真智, 平田 竜一, 佐藤 友徳, 小嵐 淳
     
    インドネシアの熱帯泥炭林の炭素収支と蒸発散量の変動を解析し，火災の影響が撹乱履歴や気象条件によって異なることを明らかにするとともに，蒸発散量を蒸発と蒸散に分離することに成功した。また，泥炭の嫌気条件下での培養実験により，酸性から中性へと土壌を中和することでメタンの生成量がオーダーレベルで増加した。さらに，熱帯泥炭の放射性炭素（14C）同位体比を分析するための前処理法として，溶液試料から溶存有機炭素を固体試料として回収することに成功した。オイルパームのからのイソプレン放出能を簡易に評価するため簡易測定法を開発し，測定に最適なインキュベーション時間や温度，光照射時間等を明らかにした。 ボルネオ島南部の熱帯泥炭林の実測データを用いて改良を行った陸域生態系モデルを，ボルネオ島西部の熱帯泥炭林のデータを用いて検証を行った結果，観測とモデル出力値には剥離があり，特に呼吸量の推定に問題があることが判明した。また，2000～2019年の衛星画像（MODIS）を収集し，各年の土地被覆図を作成した。森林のバイオマス分布を把握するため，衛星ライダーGEDIの地上部バイオマス・プロダクトを収集した。さらに，泥炭湿地林をオイルパーム農園に転換したエリアで合成開口レーダPALSAR-2（Lバンド）とSentinel-1（Cバンド）の時系列干渉SAR解析を実施し，地盤沈降量分布の時間変化を把握した。 前年度に実施した領域気候モデル実験の空間解像度を9 kmから3 kmへと向上させた。これにより土地利用変化に対する地域気候応答の評価における不確実性の主要因の一つである積雲対流スキームを用いることなく，対流活動を再現できた。実験結果をもとに水循環に対する熱帯雨林の寄与を評価したところ，熱帯雨林は蒸発散を増加させることに加えて風の変化を通じて水蒸気フラックスの収束を強めることが分かった。
  • 日本学術振興会：科学研究費助成事業 基盤研究(S)
    研究期間 : 2019年06月 -2024年03月 
    代表者 : 檜山 哲哉, 立花 義裕, 佐藤 友徳, 朴 昊澤, 市井 和仁, 石川 守, 植山 雅仁, 伊藤 昭彦, 飯島 慈裕, 小谷 亜由美, 鈴木 和良, 水落 裕樹
     
    4つの班が連携し、目的達成に向けた活動を開始した。陸域観測班は、東シベリア・カラマツ林用の海外寒冷地向けフラックス観測システムの国内試験を行った。新型コロナウイルスの蔓延により観測システムの輸送は実現していないものの、既存のシステムを活用して現地観測データを取得中である。また、過去約20年間に取得されたフラックス観測データ、衛星観測データ、モデル出力結果を収集してデータセットを構築した。東シベリアのカラマツ林観測サイトにおける正規化植生指数（NDVI）の長期変化傾向と生育期における気温と降水量の長期変化傾向との関わりを調べた結果、スパスカヤパッド（Spasskaya Pad）では生育期のNDVIが有意な増加傾向を示さず気温や降水量との相関が見いだせなかった一方、エルゲイ（Elgeeii）では生育期のNDVIが増加傾向を示し、気温と降水量の増加傾向と一致した。したがって、温暖化は北方林の生育にプラスに寄与するのみならず、降水量増加によってダメージを与えうることが示唆された。陸域モデル班は、融雪水・暖候期降水・地下氷融解水を成分分離し、北ユーラシアの河川流域におけるそれらの寄与率を定量評価可能なトレーサーモデルを開発した。東シベリアのスパスカヤパッド観測サイトにモデルを適用し、従来の観測データと比較・検証した結果、蒸発散量に対する暖候期降水の寄与が著しく大きいことを見出した。大気班は水蒸気トレーサーモデルの開発・改良に着手した。バレンツ海とカラ海における11月の海氷面積が小さいほど北極海起源の水蒸気の割合が増加し、シベリアで降水量が増加することを確認した。統括班は米国地球物理学連合（AGU）等の国際会議や国内学会での成果公表を開始した。東シベリアやモンゴルの共同研究者と協働し、2020年3月開催予定で国際シンポジウムを企画したが、新型コロナウイルスの蔓延により中止となった。
  • 日本学術振興会：科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))
    研究期間 : 2018年10月 -2022年03月 
    代表者 : 藤波 初木, 佐藤 友徳, 平田 英隆, 高橋 暢宏, 藤田 耕史
     
    本課題は10月上旬より研究活動を開始した.12月3日～4日に名古屋大学にて研究分担者と研究協力者等(全14名）が参加してキックオフワークショップを開催し,本課題の具体的な研究目標や課題を共有した.2019年の暖候期から開始する降水量観測の準備として,測器(雨量計や温度計等)の選定と購入等を行った.3月5日～17日かけて, 研究代表者と研究協力者(全2名)がネパールに滞在し,ヒマラヤ山脈ロールワリン地方に新設する雨量計の設置場所6地点の選定と現地調査を行った.また,研究協力者が所属するカトマンズ大学と,今後共同研究を開始予定の国際総合山岳研究センター及びネパール水文気象局を訪問した.訪問した際に,本研究課題の趣旨と課題を教員,ポスドク研究員及び学生等に紹介して研究交流を行い,現地観測やデータ共有を含む共同研究体制を確認した. 研究に関しては,分担者が先行研究で実施したロールワリン地方の氷河質量収支の観測, 自動気象観測装置(AWS)の降水量データ及び流域水収支を用いて,ヒマラヤ高標高域の降水の推定を行った.ヒマラヤ域における衛星搭載降水データによる高解像度降水情報を用意し,長期平均値の地理的分布の状況や複雑地形に関連する推定誤差を吟味し,衛星データ利用価値や課題に関する理解を深めた.また,GPM二周波降水レーダのデータを整備し,ヒマラヤ山岳域の降水特性の初期解析を行った.AWSで観測された2016～2017年暖候期の1時間間隔の降水量データの初期解析を行い,ヒマラヤ高標高域の降水量変動とベンガル湾で発生するモンスーン低気圧との関係を確認した.また,モンスーン低気圧の自動追跡や流跡線解析を行うためのプログラム群の作成及び準備を行った.ヒマラヤにおける降水システムの高解像度雲解像シミュレーションのテスト実験を実施し,水平解像度約3kmの設定で実行可能であることを確認した.
  • 文部科学省：統合的気候モデル高度化研究プログラム
    研究期間 : 2020年04月 -2022年03月
  • 北極水循環変化：環境の持続可能性と自然資源へのインパクト
    科学技術振興機構：国際科学技術共同研究推進事業（戦略的国際共同研究プログラム), 北極観測および北極域における自然利用とエネルギー資源開発のための科学技術
    研究期間 : 2019年04月 -2022年03月
  • 北東ユーラシアにおける降水観測ミッション陸域共同検証研究
    宇宙航空研究開発機構：降水観測ミッション
    研究期間 : 2016年04月 -2019年03月
  • ①信頼度の高い近未来予測技術開発, ②超高解像度ダウンスケーリグ技術の開発
    文部科学省：気候変動適応技術社会実装プログラム（ＳＩ－ＣＡＴ）
    研究期間 : 2015年 -2019年 
    代表者 : 木村 富士男, 石川 洋一
  • 北極域環境における多圏相互作用の実態解明と気候予測への応用
    文部科学省：北極域研究推進プロジェクト【環境技術等開発事業費補助金】 ArCS
    研究期間 : 2015年 -2019年 
    代表者 : 深澤 理郎
  • 日本学術振興会：科学研究費補助金 （若手研究A）
    研究期間 : 2015年 -2018年 
    代表者 : 佐藤 友徳
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2014年04月 -2016年03月 
    代表者 : 飯塚 芳徳, 中村 一樹, 佐藤 友徳
     
    本研究では、氷昇華法を厳寒地の北海道占冠・トマム地域の降雪に応用し、海塩・硫酸塩などが固体微粒子として存在する寒冷な降雪とともに湿性沈着したエアロゾルの粒子状物質の化学組成を分析し、湿性沈着エアロゾルの粒子状物質を明らかにすることを目的とした。分析の結果、エアロゾル微粒子と降雪中の不揮発性微粒子の元素組成分布には違いがみられ、降雪中の不揮発性粒子には塩化物塩が多く見つかった。しかしながら、ダイヤモンドダストに含まれる不揮発性粒子には塩化物塩が含まれておらず、エアロゾルの組成分布とよく似ていた。
  • 超高解像度観測と数値モデルによる大雪や突風をもたらす降雪雲の動態に関する研究
    日本学術振興会：科学研究費補助金 （基盤研究A）
    研究期間 : 2014年 -2016年 
    代表者 : 山田 芳則
  • 北極気候変動分野「急変する北極気候システム及びその全球的な影響の総合的解明」北極温暖化のメカニズムと全球気候への影響：大気プロセスの包括的研究
    文部科学省：グリーン・ネットワーク・オブ・エクセレンス（GRENE）事業
    研究期間 : 2013年 -2015年 
    代表者 : 浮田 甚郎
  • 確率モデリングによる境界永久凍土分布図の作成
    日本学術振興会：科学研究費補助金（基盤研究C）
    研究期間 : 2013年 -2015年 
    代表者 : 石川 守
  • 気候系のhot spot: 熱帯と寒帯が近接するモンスーンアジアの大気海洋結合変動, 大気・海洋・海氷相互作用系の変動による北日本の冬季降水への影響
    日本学術振興会：科学研究費補助金 新学術領域 公募研究
    研究期間 : 2013年 -2014年 
    代表者 : 中村 尚
  • 気候変動適応研究推進プログラム, 北海道を対象とする総合的ダウンスケール手法の開発と適用
    文部科学省：気候変動適応研究推進プログラム
    研究期間 : 2010年 -2014年 
    代表者 : 三村 信男
  • S-8 温暖化影響評価・適応政策に関する総合的研究, S-8-1(2)温暖化ダウンスケーラの開発とその実用化, S-8-1(2)③影響評価研究者および政策担当者との連携とダウンスケーラの有用性の評価
    環境省：環境研究総合推進費
    研究期間 : 2010年 -2014年 
    代表者 : 三村 信男
  • 文部科学省：科学研究費補助金（基盤研究B）
    研究期間 : 2010年 -2012年 
    代表者 : 安成 哲三
  • 全球雲解像大気モデルの熱帯気象予測への実利用化に関する研究
    科学技術振興機構：戦略的創造研究推進事業(CREST)
    研究期間 : 2005年10月 -2011年03月
  • 土地利用変化と地球温暖化による北東アジアの気候変動予測の数値実験
    日本学術振興会：優秀若手研究者海外派遣制度
    研究期間 : 2010年03月 -2010年06月 
    代表者 : 佐藤 友徳
  • 文部科学省：科学研究費補助金（若手研究スタートアップ）
    研究期間 : 2008年 -2009年 
    代表者 : 佐藤 友徳
     
    全球雲解像モデルNICAMによる熱帯地域の降水日変化についてTRMMによる衛星観測データと比較を行った。その結果、従来の全球モデルに比べて日変化の位相や振幅が大幅に改善されることが示された。また、日変化の解像度依存性やメソスケール循環との関係について新たな知見が得られた。
  • 日本学術振興会：科学研究費補助金（特別研究員奨励費）
    研究期間 : 2006年04月 -2007年11月 
    代表者 : 佐藤 友徳
  • 北東アジア植生変遷域の水循環と生物・大気圏の相互作用の解明
    科学技術振興機構：戦略的創造研究推進事業(CREST)
    研究期間 : 2001年 -2006年
  • Impact of Initialized Land Temperature and Snowpack on Sub-seasonal to Seasonal Prediction (LS4P)
    GEWEX/GASS：

教育活動情報

主要な担当授業

  • 水循環学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 水循環, 気象学, 気候学, 水文学, 人間活動 Hydrological cycle, Climatology, Meteorology, Hydrology, Human activities
  • 気候変動影響特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 気候変動; 地球温暖化; リスク、影響、適応; 極端気象; 炭素循環; 生態系; 水資源; 農業 Climate change; Global warming; Risks, impacts and adaptation; Extreme weather events; Carbon cycle; Ecosystems; Water resources; Agriculture
  • 自然環境学総論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 生態系、環境、気候、物質循環、モデル ecosystem, environment, climate, material cycling, model
  • 統合自然環境調査法実習
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 同定、植物種、動物種、気象 Identification, plant species, animal species, climate
  • 大学院共通授業科目（教育プログラム）：JICA開発大学院連携プログラム環境科学
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 気候変動とその対策、持続可能な開発目標、生態系、生物多様性、生態系を利用した災害緩和、生態系撹乱、環境修復、湿地・湿原、里山、植生、オゾン枯渇、化学センサー、環境計測 global warming and its countermeasure, sustainable development goals, ecosystems, biodiversity, disaster reduction using ecosystem, ecological disturbance, remediation, wetland, satoyama, vegetation, ozone depletion, chemical sensor, environmental monitoring
  • 大学院共通授業科目（教育プログラム）：RJE3
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 野外観測、タイガ、永久凍土、環境、文化
  • 大学院共通授業科目（一般科目）：自然科学・応用科学
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : SDGs, sustainability, resources, energy, inequality, climate change, ecosystem, biodiversity, disaster, community
  • 環境科学総論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : SDGs, sustainability, resources, energy, inequality, climate change, ecosystem, biodiversity, disaster, community

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