2010年度日本海洋学会岡田賞　　　　　　　　　　　　　　　
北太平洋亜寒帯の海洋構造と動態の解析研究
上野洋路

Multidecadal decline in sea ice meltwater volume and Pacific Winter Water salinity in the Bering Sea revealed by ocean observations
Vigan Mensah, Yen-Chen Chen, Daiki Nomura, Hiromichi Ueno, Hwa Chien, Kay I. Ohshima
Progress in Oceanography, 230, 103377, 103377, Elsevier BV, Jan. 2025, [Peer-reviewed]
Scientific journal

黒潮親潮混合域における高気圧性渦が魚類分布に与える影響—Impact of anticyclonic eddy on fish distribution in the Kuroshio-Oyashio transition area
土橋 稜, 上野 洋路, 加藤 陸, 閻 乃筝, 向井 徹, 安間 洋樹, 野村 大樹, 伊藤 幸彦, 笠井 亮秀
水産海洋研究 = Bulletin of the Japanese Society of Fisheries Oceanography, 88, 3, 178, 189, 東京 : 水産海洋学会, Aug. 2024, [Peer-reviewed]
Japanese

The Pacific water flow branches in the eastern Chukchi Sea
Robert S. Pickart, Peigen Lin, Frank Bahr, Leah T. McRaven, Jie Huang, Astrid Pacini, Kevin R. Arrigo, Carin J. Ashjian, Catherine Berchok, Mark F. Baumgartner, Kyoung Ho Cho, Lee W. Cooper, Seth L. Danielson, Douglas Dasher, Amane Fuiwara, Jeanette Gann, Jacqueline M. Grebmeier, Jianfeng He, Toru Hirawake, Motoyo Itoh, Lauren Juranek, Takashi Kikuchi, G. W.K. Moore, Jeff Napp, R. John Nelson, Shigeto Nishino, Hank Statscewich, Phyllis Stabeno, Kathleen M. Stafford, Hiromichi Ueno, Svein Vagle, Thomas J. Weingartner, Bill Williams, Sarah Zimmermann
Progress in Oceanography, 219, Dec. 2023
Scientific journal, The flow of Pacific-origin water across the Chukchi Sea shelf impacts the regional ecosystem in profound ways, yet the two current branches on the eastern shelf that carry the water from Bering Strait to Barrow Canyon – the Alaskan Coastal Current (ACC) and Central Channel (CC) Branch – have not been clearly distinguished or quantified. In this study we use an extensive collection of repeat hydrographic sections occupied at three locations on the Chukchi shelf, together with data from a climatology of shipboard velocity data, to accomplish this. The data were collected predominantly between 2010 and 2020 during the warm months of the year as part of the Distributed Biological Observatory and Arctic Observing Network. The mean sections show that mass is balanced for both currents at the three locations: Bering Strait, Point Hope, and Barrow Canyon. The overall mean ACC transport is 0.34 ± 0.04 Sv, and that of the CC Branch is 0.86 ± 0.11 Sv. The dominant hydrographic variability at Bering Strait is seasonal, but this becomes less evident to the north. At Barrow Canyon, the dominant hydrographic signal is associated with year-to-year variations in sea-ice melt. Farther south there is pronounced mesoscale variability: an empirical orthogonal function analysis at Bering Strait and Point Hope reveals a distinct ACC mode and CC Branch mode in hydrography and baroclinic transport, where the former is wind-driven. Finally, the northward evolution in properties of the two currents is investigated. The poleward increase in salinity of the ACC can be explained by lateral mixing alone, but solar heating together with wind mixing play a large role in the temperature evolution. This same atmospheric forcing also impacts the northward evolution of the CC Branch.

Evaluating the sampling effort for the metabarcoding-based detection of fish environmental DNA in the open ocean
Tatsuya Kawakami, Aya Yamazaki, Maki Asami, Yuko Goto, Hiroki Yamanaka, Susumu Hyodo, Hiromichi Ueno, Akihide Kasai
ECOLOGY AND EVOLUTION, 13, 3, WILEY, Mar. 2023
English, Scientific journal, Clarifying the effect of the sampling protocol on the detection of environmental DNA (eDNA) is essential for appropriately designing biodiversity research. However, technical issues influencing eDNA detection in the open ocean, which consists of water masses with varying environmental conditions, have not been thoroughly investigated. This study evaluated the sampling effort for the metabarcoding-based detection of fish eDNA using replicate sampling with filters of different pore sizes (0.22 and 0.45 mu m) in the subtropical and subarctic northwestern Pacific Ocean and Arctic Chukchi Sea. The asymptotic analysis predicted that the accumulation curves for detected taxa did not saturate in most cases, indicating that our sampling effort (7 or 8 replicates, corresponding to 10.5-40 L of filtration in total) was insufficient to fully assess the species diversity in the open ocean and that tens of replicates or a substantial filtration volume were required. The Jaccard dissimilarities between filtration replicates were comparable with those between the filter types at any site. In subtropical and subarctic sites, turnover dominated the dissimilarity, suggesting that the filter pore size had a negligible effect. In contrast, nestedness dominated the dissimilarity in the Chukchi Sea, implying that the 0.22 mu m filter could collect a broader range of eDNA than the 0.45 mu m filter. Therefore, the effect of filter selection on the collection of fish eDNA likely varies depending on the region. These findings highlight the highly stochastic nature of fish eDNA collection in the open ocean and the difficulty of standardizing the sampling protocol across various water masses.

Review of oceanic mesoscale processes in the North Pacific: Physical and biogeochemical impacts
Hiromichi Ueno, Annalisa Bracco, John A. Barth, Maxim V. Budyansky, Daisuke Hasegawa, Sachihiko Itoh, Sung Yong Kim, Carol Ladd, Xiaopei Lin, Young Gyu Park, Sergey Prants, Tetjana Ross, Irina I. Rypina, Yoshikazu Sasai, Olga O. Trusenkova, Elena I. Ustinova, Yisen Zhong
Progress in Oceanography, 212, Mar. 2023
Scientific journal, Physical transport dynamics occurring at the ocean mesoscale (∼20 km – 200 km) largely determine the environment in which biogeochemical processes occur. As a result, understanding and modeling mesoscale transport is crucial for determining the physical modulations of the marine ecosystem. This review synthesizes current knowledge of mesoscale eddies and their impacts on the marine ecosystem across most of the North Pacific and its marginal Seas. The North Pacific domain north of 20°N is divided in four regions, and for each region known, unknowns and known-unknowns are summarized with a focus on physical properties, physical-biogeochemical interactions, and the impacts of climate variability and change on the eddy field and on the marine ecosystem.

Distribution and habitat preference of polar cod (Boreogadus saida) in the Bering and Chukchi Seas inferred from species-specific detection of environmental DNA
Tatsuya Kawakami, Aya Yamazaki, Hai Chao Jiang, Hiromichi Ueno, Akihide Kasai
Frontiers in Marine Science, 10, 2023
Scientific journal, Ongoing warming and sea-ice reductions in the Arctic can seriously impact cold-water species, such as polar cod (Boreogadus saida), necessitating biomonitoring to reveal the ecological consequences. Recent methodological advancements in environmental DNA (eDNA) techniques have increased our ability to conduct ecological monitoring at various locations, including the Arctic. This study aimed to provide an overview of the distribution of polar cod across the Bering and Chukchi Seas by employing species-specific detection of eDNA. First, we successfully developed novel species-specific qPCR assay targeting the mitochondrial D-loop region, which exclusively amplifies eDNA derived from polar cod. Subsequently, polar cod eDNA was detected using the assay from the samples that we collected latitudinally across the study area during the open-water season. Polar cod eDNA was primarily detected in the surface water from the central Chukchi Sea shelf and the northernmost observation line (75°N), which was located on the shelf slope, off the Point Barrow, and in the marginal ice zone. In contrast, only trace amounts of eDNA were detected in the Bering Sea. This pattern corresponded well with the distribution of water masses classified based on environmental conditions. The detection of eDNA in surface water was clearly limited to cold (-1 to 5°C) and low salinity (25–32) water, whereas it was detected in a higher salinity range (32–34) in the middle and bottom layers. These findings are consistent with current knowledge about the distribution and habitat of the polar cod, suggesting that eDNA can be regarded as a reliable tool to replace or supplement conventional methods. Incorporating eDNA techniques into large-scale oceanographic surveys can improve the spatial and temporal resolution of fish species detection with a reasonable sampling effort and will facilitate the continuous monitoring of Arctic ecosystems.

Marine sediment as a likely source of methyl and ethyl iodides in subpolar and polar seas
Atsushi Ooki, Keita Minamikawa, Fanxing Meng, Naoya Miyashita, Toru Hirawake, Hiromichi Ueno, Yuichi Nosaka, Tetsuya Takatsu
Communications Earth & Environment, 3, 1, Springer Science and Business Media LLC, 12 Aug. 2022, [Peer-reviewed], [International Magazine]
Scientific journal, Abstract

The surface ocean is an important source of longer-lived volatile organic iodine compounds, such as methyl and ethyl iodide. However, their production in deep waters is poorly constrained. Here, we combine shipborne seawater and sediment core analyses to investigate the temporal and vertical distribution of methyl and ethyl iodide concentrations in the Bering and Chukchi Seas in July 2017 and 2018, and Funka Bay, Japan, between March 2018 and December 2019. We find the highest methyl and ethyl iodide concentrations in sediment porewaters and at the sediment surface. In Funka Bay, concentrations in the sediment and bottom waters strongly increased following the spring bloom and subsequent settling of phytodetritus to the seafloor. Dark incubation experiments suggest that diatom aggregates are a source of methyl and ethyl iodide to the ambient water. Our findings suggest that phytodetritus at the seafloor is a potential source of volatile organic iodine compounds to the water column in polar and subpolar coastal oceans.

Atmosphere-sea ice-ocean interaction study in Saroma-ko Lagoon, Hokkaido, Japan 2021
Nomura, D, Ikawa, H, Kawaguchi, Y, Kanna, N, Kawakami, T, Nosaka, Y, Umezawa, S, Tozawa, M, Horikawa, T, Sahashi, R, Noshiro, T, Kaba, I, Ozaki, M, Kondo, F, Ono, K, Yabe, I. S, Son, E. Y, Toyoda, T, Kameyma, S, Wang, C, Obata, H, Ooki, A, Ueno, H, Kasai, A
Bulletin of Glaciological Research, 40, 1, 17, Japanese Society of Snow and Ice, 2022, [Peer-reviewed]
English, Scientific journal

Global distribution and interannual variation in the winter halocline
Ueno, H., M. Oda, K. Yasui, R. Dobashi, H. Mitsudera
Journal of Physical Oceanography, American Meteorological Society, 22 Dec. 2021, [Peer-reviewed], [Lead author]
Scientific journal, Abstract

The distribution and interannual variation in the winter halocline in the upper layers of the world ocean were investigated via analyses of hydrographic data from the World Ocean Database 2013 using a simple definition of the halocline. A halocline was generally observed in the tropics, equatorward portions of subtropical regions, subarctic North Pacific and Southern Ocean. A strong halocline tended to occur in areas where the sea surface salinity (SSS) was low. The interannual variation in halocline strength was correlated with variation in SSS. The correlation coefficients were usually negative: the halocline was strong when the SSS was low. However, in the Gulf of Alaska in the northeastern North Pacific, the correlation coefficient was positive. There, halocline strength was influenced by interannual variation in Ekman pumping.

Quantitative Estimation of the Ecosystem Services Supporting the Growth of Japanese Chum Salmon
Yuka Karasawa, Hiromichi Ueno, Ryo Tanisugi, Ryo Dobashi, Seokjin Yoon, Akihide Kasai, Masashi Kiyota
NPAFC Technical Report, 17, North Pacific Anadromous Fish Commission, 29 Nov. 2021, [Corresponding author], [International Magazine]
International conference proceedings

Impact of mesoscale eddies on particulate organic carbon flux in the western subarctic North Pacific
Ryo Dobashi, Hiromichi Ueno, Nozomi Matsudera, Isao Fujita, Tetsuichi Fujiki, Makio C. Honda, Naomi Harada
Journal of Oceanography, Springer Science and Business Media LLC, 01 Oct. 2021, [Peer-reviewed], [International Magazine]
Scientific journal

Water mass distribution in the northern Bering and southern Chukchi seas using light absorption of chromophoric dissolved organic matter
Toru Hirawake, Joji Oida, Youhei Yamashita, Hisatomo Waga, Hiroto Abe, Jun Nishioka, Daiki Nomura, Hiromichi Ueno, Atsushi Ooki
Progress in Oceanography, 197, 102641, 102641, Elsevier BV, Sep. 2021, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
Scientific journal, The northern Bering Sea (NBS) and southern Chukchi Sea (SCS) contain several water masses with different characteristics that have been conventionally classified using temperature and salinity data. However, recent warming and sea ice decline can change these water properties, which suggests that classifying water masses using temperature–salinity diagrams could be problematic for this region. We used the light absorption coefficient of chromophoric dissolved organic matter (CDOM), aCDOM, as an alternative way to classify water masses. The aCDOM spectra of several water depths were measured in the NBS, the Gulf of Anadyr included, and SCS in July 2017 and 2018, and August 2018. Optical parameters that indicate CDOM quantity and quality, aCDOM(350) and spectral slopes (S275–295 and S350–400), were calculated for each sample; water masses were classified using cluster analysis. When surface waters in the NBS and SCS are classified on the basis of the conventional method using a temperature–salinity diagram, they are mistakenly identified as Alaskan Coastal Water because of warmer temperatures. However, our cluster analysis using CDOM parameters evenly classified seven water masses with reasonable distributions. A water mass with the highest aCDOM(350) and lowest S275–295 was found along the coast of the Gulf of Anadyr and Alaska mainland, which suggests that freshwater originates from the Anadyr and Yukon rivers and is transported by the Anadyr Current and Alaskan Coastal Current, respectively. A CDOM-based water mass with high S275–295, indicating CDOM degradation by ultraviolet radiation, was present at the sea surface. A water mass with low S275–295 was found at deeper water depths and river mouths. These results suggest that classification with CDOM parameters is consistent with geographical features. In addition, we recognized a water mass with high nitrate concentrations, which is likely Anadyr Water that originates in the region from the Bering Slope to the Gulf of Anadyr. Overall, this study reveals that water mass classification using CDOM parameters is useful in coastal sea areas in which water mass mixing is complex.

Transport and heat loss of the Pacific Summer Water in the Arctic Chukchi Sea northern slope: Mooring data analysis
Miaki Muramatsu, Hiromichi Ueno, Eiji Watanabe, Motoyo Itoh, Jonaotaro Onodera
Polar Science, 100698, 100698, Elsevier BV, Jun. 2021, [Peer-reviewed], [International Magazine]
Scientific journal

The potential role of thermohaline-shear instability in turbulence production in the Bering Sea and the subarctic North Pacific
Mamoru Tanaka, Jiro Yoshida, Keunjong Lee, Yasutaka Goto, Takahiro Tanaka, Hiromichi Ueno, Hiroji Onishi, Ichiro Yasuda
JOURNAL OF OCEANOGRAPHY, 77, 3, 431, 446, SPRINGER, Jun. 2021, [Peer-reviewed], [International Magazine]
English, Scientific journal, A recent linear stability analysis and a numerical simulation suggest that diffusive convection (DC), a regime of the double-diffusive convection, plays a potential role in onset of thermohaline-shear instability, implying that DC could contribute to turbulence production in the oceans. However, an existence of such a thermohaline-shear instability has not been examined in real oceans. We examine if this newly proposed instability mechanism exists in the subarctic North Pacific by analyzing our fine- and micro-scale turbulence measurement data. Vertical inversions were cautiously detected in seawater density profiles and used as a proxy for instability events for gradient Richardson number larger than the critical value of 1/4. We found that a portion of inversions were associated with active DC. Such DC-related inversions exhibited elevated levels of turbulent kinetic energy dissipation rate even for gradient Richardson number largely exceeding 1/4. Our estimate suggested that the thermohaline-shear instability contributes to roughly only 10% of the dissipation of turbulent kinetic energy in the diffusively convective layer in our observation site.

Observations of anticyclonic eddies in the western subarctic North Pacific
Ryo Dobashi, Hiromichi Ueno, Yuki Okada, Takahiro Tanaka, Jun Nishioka, Toru Hirawake, Atushi Ooki, Sachihiko Itoh, Daisuke Hasegawa, Yoshikazu Sasai, Hideharu Sasaki, Ichiro Yasuda
JOURNAL OF OCEANOGRAPHY, 77, 2, 229, 242, SPRINGER, Apr. 2021, [Peer-reviewed], [International Magazine]
English, Scientific journal, © 2021, The Oceanographic Society of Japan and Springer Nature Singapore Pte Ltd. We conducted a ship observation of two anticyclonic mesoscale eddies (Eddies A and B) between June and July 2016 in the offshore region of the western subarctic North Pacific to clarify the impact of anticyclonic eddies on biological production. Analysis of satellite data reveals that Eddy A formed south of the Alaskan Peninsula on May 2011 while Eddy B formed in the observation area on November 2015. Iron concentration was low both inside and outside Eddies A and B, and there were no large differences between chlorophyll a (chl-a) concentration inside and outside eddies. Satellite-derived chl-a concentration inside Eddy A had been high compared with that in the surrounding area when the eddy was located along the Aleutian Islands and just after it detached from the islands, suggesting that iron originating from the coastal region was consumed during the two-year journey from the coastal region to the observation area. Field measurements also reveal that vertical diffusivity was low both inside and outside Eddies A and B, which could be another factor underlying low iron both inside and outside Eddies A and B and small differences between chl-a concentration inside and outside the eddies.

Timing of spring sea-ice retreat and summer seabird-prey associations in the northern Bering Sea
Bungo Nishizawa, Nodoka Yamada, Haruka Hayashi, Charlie Wright, Kathy Kuletz, Hiromichi Ueno, Tohru Mukai, Atsushi Yamaguchi, Yutaka Watanuki
Deep-Sea Research Part II: Topical Studies in Oceanography, 181-182, Dec. 2020, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
Scientific journal, © 2020 Elsevier Ltd To understand the effect of an unusually early sea-ice retreat in the northern Bering Sea in the spring of 2018 on the marine ecosystem of the northern Bering Sea, we compared at-sea observations of seabird density and acoustic observations of prey (fish and zooplankton) biomass during shipboard surveys around St. Lawrence Island in the summers of 2017 and 2018. Densities of foraging seabirds in 2018 (piscivorous divers: 4.7 birds km−2, planktivorous divers: 5.1, shearwaters: 0.7, surface feeders: 6.6) were lower than those in 2017 (piscivorous divers: 14.7 birds km−2, planktivorous divers: 10.3, shearwaters: 11.9, surface feeders:11.9). Acoustically-determined prey biomass in 2018 (fish: 6.4 m2nmi−2, zooplankton: 2.3) was also lower than in 2017 (fish: 18.4 m2nmi−2, zooplankton: 5.5). Similarly, biomass of macrozooplankton (amphipods, euphausiids, Neocalanus spp. and Calanus marshallae) sampled using bongo nets was smaller in 2018. At scales of 5–30 km, correlations between the seabird density and prey biomass were weaker (−0.2–0.3 of Pearson's r) in 2018 than those in 2017 (0.4–0.9) for all seabirds except planktivorous divers. We suggest that the lack of sea ice, and the resulting lack of ice-edge phytoplankton blooms, may weaken trophic linkages by causing a low biomass of secondary consumers and hence a reduced density of seabirds.

Stratification in the northern Bering Sea in early summer of 2017 and 2018
Hiromichi Ueno, Mizuki Komatsu, Zhaoqianyi Ji, Ryo Dobashi, Miaki Muramatsu, Hiroto Abe, Keiri Imai, Atushi Ooki, Toru Hirawake
Deep-Sea Research Part II: Topical Studies in Oceanography, 181-182, 104820, 104820, PERGAMON-ELSEVIER SCIENCE LTD, Dec. 2020, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, © 2020 Elsevier Ltd We investigated spatial and interannual variation in the physical environment in the northern Bering Sea focusing on stratification, which is one factor affecting biological production in Arctic/subarctic regions. In particular, we analyzed in situ data obtained onboard the training ship Oshoro Maru in early summer in 2017 and 2018. We found that stratification in the areas just north of St. Lawrence Island (around 64.5°N and west of 168.5°W) and south/southwest of St. Lawrence Island was significantly weaker in 2018 than in 2017. These results are consistent with the extremely low sea-ice extent present in the winter of 2017/2018, which would have resulted in less freshwater being supplied to the surface layers and a warmer and less saline bottom water. Conversely, stratification was as strong in 2018 as in 2017 in the area close to the Alaska mainland, including the Bering Strait area, suggesting that the Alaskan Coastal Water dominates stratification in this area in early summer. Moreover, we found that the weakly stratified water column in the Bering Strait area stratified quickly shortly after the occurrence of strong northerly winds, likely because of the Ekman transport of warm and low-salinity Alaskan Coastal Water from the east.

Quantitative estimation of the ecosystem services supporting the growth of Japanese chum salmon
Yuka Karasawa, Hiromichi Ueno, Ryo Tanisugi, Ryo Dobashi, Seokjin Yoon, Akihide Kasai, Masashi Kiyota
Deep-Sea Research Part II: Topical Studies in Oceanography, 175, 104702, 104702, Elsevier BV, May 2020, [Peer-reviewed], [Corresponding author], ［Internationally co-authored］, [International Magazine]
Scientific journal, © 2019 Elsevier Ltd Chum salmon (Oncorhynchus keta) are distributed widely in the subarctic North Pacific. The Japanese stock is maintained by artificial release procedures. Chum salmon, including the Japanese stock, provide important ecosystem services for humans that are related to provisioning, culture and support. These ecosystem services are supported by the supply of prey and habitat that the fish use. We regard the supply of prey and habitat as supporting services for salmon. We developed a procedure to estimate supporting services quantitatively, based on the prey biomass consumed by individual salmon, by coupling a bioenergetics model and a lower trophic level ecosystem model. Using this procedure, we estimated the prey biomass consumed by a cohort of Japanese chum salmon released in a single year. The phytoplankton biomass indirectly consumed by a cohort was also estimated and considered to be the primary production supporting the fish. The Japanese chum salmon cohort was estimated to consume ca. 4.2–4.7 × 109 kg wet weight of zooplankton, of which more than half is eaten in the Bering Sea. The Japanese chum salmon cohort is supported by an estimated primary production of 2.0–2.2 × 109 kg C, which amounts to 0.17%–0.19% of primary production in the areas and periods through which the fish migrate. We also attempted to calculate the monetary value of supporting services for the growth of Japanese chum salmon.

Response of Arctic biodiversity and ecosystem to environmental changes: Findings from the ArCS project
Toru Hirawake, Masaki Uchida, Hiroto Abe, Irene D. Alabia, Tamotsu Hoshino, Shota Masumoto, Akira S. Mori, Jun Nishioka, Bungo Nishizawa, Atsushi Ooki, Akinori Takahashi, Yukiko Tanabe, Motoaki Tojo, Masaharu Tsuji, Hiromichi Ueno, Hisatomo Waga, Yuuki Y. Watanabe, Atsushi Yamaguchi, Youhei Yamashita
Polar Science, 27, 100533, 100533, Elsevier BV, 2020, [Peer-reviewed], [International Magazine]
Scientific journal, © 2020 Elsevier B.V. and NIPR Arctic ecosystems are altered profoundly by climate changes. However, the responses of Arctic marine and terrestrial ecosystems as well as their biodiversity to global warming remain largely unknown. This article provides comprehensive insights into the results and major findings from the Arctic Challenge for Sustainability (ArCS) Project – an Arctic region research program initiated in Japan, which aims to address and advance our understanding of these uncertainties. Marine ecosystem studies have identified several biogeochemical processes that are associated with sea ice decline and northward transport and shift of marine species across multiple trophic levels over the Bering and Chukchi Sea shelves. Studies of the terrestrial ecosystem have identified factors that are important for the understanding of terrestrial biodiversity and ecosystems, including Arctic lakes, under the presence of global warming. Novel fungal species from the Arctic terrestrial ecosystem have also been isolated and described. Overall, these results could contribute to the conservation and sustainable management of the Arctic ecosystem services.

Impacts of Mesoscale Eddies on Phytoplankton Size Structure
Hisatomo Waga, Toru Hirawake, Hiromichi Ueno
Geophysical Research Letters, 46, 22, 13191, 13198, AMER GEOPHYSICAL UNION, 28 Nov. 2019, [Peer-reviewed], [International Magazine]
English, Scientific journal, ©2019. American Geophysical Union. All Rights Reserved. The impact of mesoscale eddies on phytoplankton communities attracts considerable research attention because phytoplankton play numerous roles in marine ecosystems. Using remote sensing techniques, this study considered a synoptic relationship between phytoplankton size structure, which is a determinant of energy transfer efficiency in marine ecosystems, and mesoscale eddies, which are ubiquitous ocean features. We found clear spatial variation in the impacts of mesoscale eddies on phytoplankton size structure; phytoplankton communities with larger cell sizes were supported by anticyclonic eddies in oligotrophic regions and by cyclonic eddies in eutrophic regions. Differences in the phytoplankton size structure within these two types of mesoscale eddies became greater, accompanied by interannual trends in the phytoplankton size structure for 2003–2014. Our findings are the first to demonstrate the important linkage between mesoscale eddies and phytoplankton size structure on a global scale; this new knowledge might help better predict variability in marine ecosystems.

Characterization of the Water Masses in the Shelf Region of the Bering and Chukchi Seas With Fluorescent Organic Matter
Youhei Yamashita, Yuki Yagi, Hiromichi Ueno, Atsushi Ooki, Toru Hirawake
Journal of Geophysical Research: Oceans, 124, 11, 7545, 7556, AMER GEOPHYSICAL UNION, 01 Nov. 2019, [Peer-reviewed], [International Magazine]
English, Scientific journal, ©2019. The Authors. Pacific water is an important nutrient source for sustaining biological production in the Chukchi Sea, western Arctic Ocean, which is one of the productive regions in the world. Therefore, to understand the impacts of future environmental changes on biological production in the sea, it is crucial to understand the origins, modification processes, and spatiotemporal variations of the water masses from the Bering Sea with changes in nutrient concentrations. To improve water mass analysis in the shelf regions of the Bering and Chukchi Seas, we observed levels of humic-like fluorescent organic matter (FOMH) by using an in situ fluorometer directly connected to a temperature-salinity sensor during a cruise in the early summer of 2013 and evaluated the potential of FOMH as a third parameter of water mass analysis. The levels of FOMH were different among specific water masses in the region, and FOMH seemed to behave semiconservatively in the shelf regions of the Bering and Chukchi Seas during the early summer of 2013. The distributional pattern of FOMH implies that FOMH estimated by the in situ fluorometer has the potential to (1) separate warm water into riverine-affected Alaskan Coastal Water and historically photobleached summer Bering Basin Water; (2) distinguish the Anadyr Water, which has low FOMH levels and high nutrient concentrations, from the Bering Shelf Water; and (3) determine different formation/modification processes of dense shelf water that contains high nutrient concentrations.

Spatial distribution and seasonality of halocline structures in the subarctic north pacific
Shota Katsura, Hiromichi Ueno, Humio Mitsudera, Shinya Kouketsu
Journal of Physical Oceanography, 49, 10, 95, 109, AMER METEOROLOGICAL SOC, Oct. 2019, [Peer-reviewed], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, © 2019 American Meteorological Society. The spatial distribution and seasonality of halocline structures in the subarctic North Pacific (SNP) were investigated using Argo profiling float data and various surface flux data collected in 2003−2017. The permanent halocline (PH) showed zonal patterns in the spatial distributions of its depth and intensity and tended to be shallow and strong in the eastern SNP but deep and weak in the west. Mean distributions of PH depth and intensity corresponded to the winter mixed layer depth and sea-surface salinity, respectively, indicating that it forms in association with the development of the winter mixed layer. In the Western Subarctic Gyre and Alaskan Gyre, where a relatively strong PH formed, PH intensity and depth showed clear seasonal variations, and deepening of the mixed layer compressed the underlying PH during the cooling period, resulting in intensification and development of the PH in late winter. In both regions, upwelling of high-salinity water also contributed to PH intensification. The summer seasonal halocline (SH) showed distinct zonal differences in frequency and intensity, which were opposite to the PH distribution. While an SH formed in the western and central SNP and coastal regions, it was seldom present in the eastern area. This zonal contrast of SH corresponded to freshening of the mixed layer during the warming period, primarily reflecting freshwater flux. Geostrophic and Ekman advection play important roles in spatial differences in SH intensity and depth. SH development contributed to PH intensification in the following winter, by decreasing salinity above the PH through entrainment.

Aquarius reveals eddy stirring after a heavy precipitation event in the subtropical North Pacific
Hiroto Abe, Naoto Ebuchi, Hiromichi Ueno, Hiromu Ishiyama, Yoshimasa Matsumura
Journal of Oceanography, 75, 1, 37, 50, SPRINGER, 01 Feb. 2019, [Peer-reviewed], [International Magazine]
English, Scientific journal, © 2018, The Oceanographic Society of Japan and Springer Japan KK, part of Springer Nature. This research presents a case study that examines an upper-ocean salinity response to intense rainfall using 4 years of observed salinity data from the Aquarius and Argo floats. The Aquarius sea surface salinity (SSS) in the subtropical region of the North Pacific reveals a notable event in which SSS is locally freshened by intense rainfall. Although the SSS pattern shortly after the rainfall reflects the atmospheric pattern, its final form reflects the ocean’s dynamic structure; low-salinity water distributes in the shape of an anticyclonic eddy. Observations using Argo profiling floats confirm that low-salinity water dominates the entire water column of the eddy above 70 m. We found that an eddy stirring effect would play an important role in forming the eddy-shaped low-salinity water. As a precondition, intense rainfall on the tropical side enhances the meridional gradient of background SSS with freshened low-salinity water to the south and saline water to the north. The anticyclonic eddy located at the enhanced SSS front stirs the water in a clockwise direction. Specifically, northward flow in the western side of the eddy transports fresh water, whereas southward flow in the eastern side transports saline water. As this northward–southward flow moves the eddy to the west where the transported fresh water is dominant as a baroclinic Rossby wave, this dynamic process would form the eddy-shaped low-salinity water. This clear view of such eddy stirring is due to the inherent nature of the subtropical region that is characterized by less frequent precipitation.

Interannual variation in solar heating in the Chukchi Sea, Arctic Ocean
Yushiro Tsukada, Hiromichi Ueno, Naoki Ohta, Motoyo Itoh, Eiji Watanabe, Takashi Kikuchi, Shigeto Nishino, Kohei Mizobata
Polar Science, 17, 33, 39, ELSEVIER SCIENCE BV, Sep. 2018, [Peer-reviewed], [Corresponding author]
English, Scientific journal, © 2018 Elsevier B.V. and NIPR Solar heating in summer in the Chukchi Sea was estimated using satellite-derived sea-ice concentration data and reanalysis shortwave radiation data. The shortwave radiation was validated by in-situ data obtained by the R/V Mirai and NCEP-CFSR/CFSv2 was found to reproduce in-situ data accurately compared with NCEP/NCAR Reanalysis 1 and ERA-Interim. Solar heating integrated over the Chukchi Sea in summer varied interannually from 3.6 × 1020 J in 2000 to 6.7 × 1020 J in 2015, and was up to twice the northward heat flux through the Bering Strait. The total heating in the Chukchi Sea implies that the heat in the Chukchi Sea provided by northward heat flux through the Bering Strait is amplified by solar heating in the Chukchi Sea. We further compared these heat fluxes into the Chukchi Sea with the summertime northward heat flux through Barrow Canyon, an indicator of heat flux from the Chukchi Sea to the Arctic basin. The northward heat flux through Barrow Canyon was affected by the interannual variation of solar heating in the eastern Chukchi Sea. These results imply that modification of Pacific water in the Chukchi Sea by solar heating plays an important role in the interannual variation in heat transport from the Chukchi Sea to the western Arctic basin.

Potential habitat for chum salmon (Oncorhynchus keta ) in the Western Arctic based on a bioenergetics model coupled with a three-dimensional lower trophic ecosystem model
Hiromichi Ueno, Seokjin Yoon, Eiji Watanabe, Michio J Kishi
Nippon Suisan Gakkaishi (Japanese Edition), 84, 5, 931, 931, JAPANESE SOC FISHERIES SCIENCE, 2018, [Lead author], ［Internationally co-authored］, [Domestic magazines]
Japanese

School Visit Program by the Oceanographic Society of Japan
上野 洋路, 小埜 恒夫, 森岡 優志, 藤井 直紀, 藤井 賢彦, 轡田 邦夫, 原田 尚美
沿岸海洋研究 = Bulletin on coastal oceanography, 55, 1, 65, 70, 日本海洋学会沿岸海洋研究部会, Aug. 2017, [Peer-reviewed], [Lead author, Corresponding author], [Domestic magazines]
Japanese

Distribution of Arctic and Pacific copepods and their habitat in the northern Bering and Chukchi seas
Hiroko Sasaki, Kohei Matsuno, Amane Fujiwara, Misaki Onuka, Atsushi Yamaguchi, Hiromichi Ueno, Yutaka Watanuki, Takashi Kikuchi
BIOGEOSCIENCES, 13, 15, 4555, 4567, COPERNICUS GESELLSCHAFT MBH, Aug. 2016, [Peer-reviewed], [International Magazine]
English, Scientific journal, The advection of warm Pacific water and the reduction in sea ice in the western Arctic Ocean may influence the abundance and distribution of copepods, a key component of food webs. To quantify the factors affecting the abundance of copepods in the northern Bering and Chukchi seas, we constructed habitat models explaining the spatial patterns of large and small Arctic and Pacific copepods separately. Copepods were sampled using NORPAC (North Pacific Standard) nets. The structures of water masses indexed by principle component analysis scores, satellite-derived timing of sea ice retreat, bottom depth and chlorophyll a concentration were integrated into generalized additive models as explanatory variables. The adequate models for all copepods exhibited clear continuous relationships between the abundance of copepods and the indexed water masses. Large Arctic copepods were abundant at stations where the bottom layer was saline; however they were scarce at stations where warm fresh water formed the upper layer. Small Arctic copepods were abundant at stations where the upper layer was warm and saline and the bottom layer was cold and highly saline. In contrast, Pacific copepods were abundant at stations where the Pacific-origin water mass was predominant (i.e. a warm, saline upper layer and saline and a highly saline bottom layer). All copepod groups showed a positive relationship with early sea ice retreat. Early sea ice retreat has been reported to initiate spring blooms in open water, allowing copepods to utilize more food while maintaining their high activity in warm water without sea ice and cold water. This finding indicates that early sea ice retreat has positive effects on the abundance of all copepod groups in the northern Bering and Chukchi seas, suggesting a change from a pelagic-benthic-type ecosystem to a pelagic-pelagic type.

Mesoscale eddy effects on temporal variability of surface chlorophyll a in the Kuroshio Extension
Shinya Kouketsu, Hitoshi Kaneko, Takeshi Okunishi, Kosei Sasaoka, Sachihiko Itoh, Ryuichiro Inoue, Hiromichi Ueno
JOURNAL OF OCEANOGRAPHY, 72, 3, 439, 451, SPRINGER, Jun. 2016, [Peer-reviewed], [International Magazine]
English, Scientific journal, We investigated the relationship between chlorophyll a (Chl-a) concentrations estimated from satellite observations and the activity of eddies in the Kuroshio Extension region. High (low) area-averaged Chl-a concentrations were frequently observed in the core of cyclonic (anticyclonic) eddies. Such relationships between Chl-a concentrations and eddy cores were not frequently observed in the southern part of the recirculation gyre, and advection of background meridional gradient of Chl-a by eddy-edge currents accounted for Chl-a spatial variability. Decadal-scale changes of Chl-a concentrations around the Kuroshio Extension were strongly affected by eddy activity and transport but not by large-scale near-surface isopycnal heaving. We also found that decadal changes of nutrient concentrations near the main stream could affect Chl-a concentrations in the southern part of the recirculation gyre via southward transport of eddies and mean flow.

Subsurface hydrographic structures and the temporal variations of Aleutian eddies
Rui Saito, Ichiro Yasuda, Kosei Komatsu, Hiromu Ishiyama, Hiromichi Ueno, Hiroji Onishi, Takeshi Setou, Manabu Shimizu
OCEAN DYNAMICS, 66, 5, 605, 621, SPRINGER HEIDELBERG, May 2016, [Peer-reviewed], [International Magazine]
English, Scientific journal, Aleutian eddies are mesoscale anticyclonic eddies formed within the Alaskan Stream region between 180A degrees meridian and 170A degrees E south of the Aleutian Islands. They propagate southwestward after the isolation from the Alaskan Stream and pass through the Western Subarctic Gyre. We compared hydrographic structures of three Aleutian eddies observed during summer, west of 170A degrees E (Eddy A) and east of 170A degrees E (Eddies B and C). In each eddy, a subsurface dichothermal water (3.0-4.0 A degrees C) was observed above a subsurface mesothermal water (4.0-4.5 A degrees C). The minimum temperature in the dichothermal water at around a depth of 100 m was colder in Eddy A (2.8 A degrees C) than in Eddies B and C (3.0-3.2 A degrees C). This difference could be ascribed to wintertime cooling and influence of surrounding waters during spring warming period. The wintertime cooling makes the dichothermal water colder for eddies isolated from the Alaskan Stream region for a longer time. Particle-tracking experiments using re-analysis products from a data-assimilative eddy resolving ocean model suggested that the dichothermal water within Eddy A was cooled by the entrainment of surrounding colder water even during the spring warming period. The mesothermal waters at depth around 250 m demonstrated similarity among the observed eddies, and the maximum temperature in the mesothermal water within Eddy A (4.3 A degrees C) was close to that of Eddies B and C (4.2 A degrees C) in the in situ observations. These results indicated that the dichothermal water of Aleutian eddies modifies over time, whereas the mesothermal water maintains the original feature as they propagate southwestward from the Alaskan Stream region to the Western Subarctic Gyre.

Temporal and Spatial Variation in a Growth Condition of Pacific Salmon　　　　　　　　　　　　　　　
Hiromichi Ueno, M. Kaeriyama, M. Otani, M. Oe, Y. Qin, M. N. Aita, S. Yoon, M. J. Kishi
North Pacific Anadromous Fish Commission (NPAFC) Bulletin, No.6, 181-187, 2016, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal

Tidal mixing and dissolved iron transport along the shelf break of the southeastern Bering Sea
田中 雄大, 安田 一郎, 久万 健志, 西岡 純, 田中 祐希, 大西 広二, 上野 洋路, 増島 雅親
海洋. 号外 = Kaiyo monthly : カラー版, 58, 47, 55, 海洋出版, 2016, [Domestic magazines]
Japanese

Potential habitat for chum salmon (Oncorhynchus keta) in the Western Arctic based on a bioenergetics model coupled with a three-dimensional lower trophic ecosystem model
Seokjin Yoon, Eiji Watanabe, Hiromichi Ueno, Michio J. Kishi
PROGRESS IN OCEANOGRAPHY, 131, 146, 158, PERGAMON-ELSEVIER SCIENCE LTD, Feb. 2015, [Peer-reviewed], [International Magazine]
English, Chum salmon (Oncorhynchus keta) are predominantly located in the Bering Sea during summer and fall. However, several studies have recently reported a different tendency as follows. Observed densities of chum salmon were higher in the vicinity of the Bering Strait and the Chukchi Sea than the eastern Bering Sea in September 2007, and Japanese chum salmon migrated to northern areas in the Bering Sea during summer 2009. The sea surface temperature (SST) in the Arctic marginal seas has increased since the mid1960s, and especially since 2000. We speculated that the SST increase directly promoted salmon northing from the Bering Sea to the Western Arctic. In this study, we estimated the potential habitat for chum salmon in the Western Arctic using a bioenergetics model coupled with a three-dimensional lower trophic ecosystem model (3-D NEMURO). "Potential habitat" was defined as "an area where chum salmon could grow (i.e., the growth rate was positive)". In the bioenergetics model, the growth rate of an individual chum salmon was calculated as a function of water temperature, salinity, and prey density, which were obtained from the 3-D NEMURO model results. To evaluate the habitat responses under a global warming scenario, we used the modeled monthly change of water temperature between 2005 (averaged from 2001 to 2010) and 2095 (averaged from 2091 to 2100) under the IPCC SRES-A1 B scenario. Our calculations, following the global warming scenario, suggested that the potential habitat for chum salmon would expand to the north due to the increase in water temperature and prey density. In contrast, south of 71 degrees N during summer, the potential habitat would shrink regionally because the water temperature exceeded the optimal condition. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

Observations of current and mixing around the shelf break in Pribilof Canyon in the Bering Sea
T. Tanaka, I. Yasuda, H. Onishi, H. Ueno, M. Masujima
Journal of Oceanography, 71, 1, 1, 17, Kluwer Academic Publishers, 2015, [Peer-reviewed], [International Magazine]
English, Scientific journal, Tide-induced vertical mixing along the shelf break in the eastern Bering Sea is considered one of the main physical processes that sustain local summertime high biological production. However, observations based on microstructure measurements that show enhanced tidal mixing are scarce. In this study, repeated casts of current and turbulence in the vicinity of the shelf break within Pribilof Canyon were conducted over a day in June 2012, enabling us to evaluate the representativeness of the vertical mixing intensity during one day and to detect the relationship between turbulence and tidal current. The cross-sectional distributions of the one-day averaged vertical diffusivity and the turbulent energy dissipation rate showed that strong vertical mixing occurred at the subsurface within about 15 km of the shelf break and near the seabed of the outer shelf. This result agrees with prior observations that were made by us and based on a single profile at each station, which indicated that the observed spatial pattern of turbulence is robust. Diurnal and semidiurnal tidal currents dominated the flow variations off the shelf break, and a statistically significant positive correlation was detected between the vertical shear of the horizontal tidal currents and the turbulent energy dissipation rate. This result suggests that the high turbulent energy dissipation and the enhanced vertical mixing off the shelf break were induced by the strong vertical shear of tidal currents.

Regeneration of a warm anticyclonic ring by cold water masses within the western subarctic gyre of the North Pacific
Sachihiko Itoh, Ichiro Yasuda, Hiromichi Ueno, Toshio Suga, Shigeho Kakehi
JOURNAL OF OCEANOGRAPHY, 70, 3, 211, 223, SPRINGER, Jun. 2014, [Peer-reviewed], [International Magazine]
English, Scientific journal, Regeneration of a warm anticyclonic ring as a result of interaction with cold water masses was observed within the western subarctic gyre of the North Pacific. Satellite, profiling float, and shipboard observations revealed that a warm-core ring originated from the Kuroshio Extension, propagating northeastwards, entrained cold and fresh water masses from the coastal area of Hokkaido, which are typically recognized within the ring as water that is colder than 2.5 A degrees C. The potential temperature and planetary contribution of potential vorticity of the cold water in the coastal area of Hokkaido were < 2 A degrees C and 15 x 10(-11) m(-1)s(-1), respectively, suggesting that it originated from the Sea of Okhotsk. After the intrusion, the warm core of the ring cooled, freshened, and contracted, while the outer and lower parts became occupied by the cold and fresh water; however, even after the cooling, the positive surface elevation and downward depression of the main pycnocline, typical of an anticyclonic ring, were still evident. The ring continued to propagate northeastwards, with the main part of its structure occupied by the cold water, but changed its direction of travel from northwest to west-southwest 8 months after the cold-water event, and was finally absorbed into another warm-core ring. It is suggested that these anticyclonic rings, which transported and mixed warm and cold water masses, play important roles in the cross-gyre exchange of subtropical and subarctic waters in the North Pacific.

East-west differences in population structure and vertical distribution of copepods along 47°N in the subarctic Pacific in June 2009
Atsushi Yamaguchi, Tomoe Homma, Rui Saito, Kohei Matsuno, Hiromichi Ueno, Toru Hirawake, Ichiro Imai
Plankton and Benthos Research, 8, 3, 116, 123, Plankton Society of Japan, 2014, [Peer-reviewed], [International Magazine]
English, Scientific journal, Stratified zooplankton sampling was conducted in the subarctic Pacific in June 2009 at four stations along 47°N from 0 to 3,000 m depth to evaluate longitudinal changes in population structure and vertical distribution of the dominant copepod species. At the westernmost station (160°E), the population structure of Eucalanus bungii and Metridia pacifica was dominated by early copepodid stages. In E. bungii, nauplii were abundant and adult females had developed ovaries at 160°E, while at the three stations to the east (167°E, 174°E and 179°W), no E. bungii nauplii were collected, and the resting stages were dominant. This suggests the species was reproducing near 160°E and in diapause in the east. In all three Neocalanus species analyzed (N. cristatus, N. flemingeri and N. plumchrus), late copepodid stages were dominant at the eastern three stations. Lipid accumulation in the fifth copepodid stage of Neocalanus spp. was greater in the west than in the east. This probably resulted from better food conditions and lower temperatures in the west, where copepods could consume more food during development than in the east.

Influences of mesoscale anticyclonic eddies on the zooplankton community south of the western Aleutian Islands during the summer of 2010
Rui Saito, Atsushi Yamaguchi, Ichiro Yasuda, Hiromichi Ueno, Hiromu Ishiyama, Hiroji Onishi, Ichiro Imai
JOURNAL OF PLANKTON RESEARCH, 36, 1, 117, 128, OXFORD UNIV PRESS, Jan. 2014, [Peer-reviewed], [International Magazine]
English, Scientific journal, Mesoscale anticyclonic eddies have been observed south of the Aleutian Islands. Eddies farther east, in the Gulf of Alaska, are known to transport coastal water and coastal zooplankton to the offshore open ocean. The impacts of mesoscale anticyclonic eddies formed south of the western Aleutian Islands (Aleutian eddies) on the zooplankton community are not fully understood. In the present study, we describe zooplankton population structures within an Aleutian eddy and outside the eddy during July 2010. Based on the sea-level anomaly, the Aleutian eddy was formed south of Attu Island (172 degrees 54'E) in February 2010, and it moved southeastward in the next 5 months. Large oceanic copepods, Neocalanus cristatus, Eucalanus bungii and Metridia pacifica were more abundant inside the eddy than the outside. Inside the eddy, the life stage distribution of N. cristatus was more advanced than that outside, and Neocalanus spp. had accumulated more lipids. These conditions probably reflect the greater primary production in the eddy, production enhanced by nutrients advected into the eddy. The Aleutian eddy contained mostly oceanic copepods because it was formed in the offshore water and/or eddy-eddy interaction occurred after its formation. The sufficient food condition in the eddy presumably resulted in higher growth and survival rates of these oceanic copepods, resulting in the greater abundance, advanced development stages and greater lipid accumulation.

Decadal variation of temperature inversions along Line P
Hiromichi Ueno
JOURNAL OF OCEANOGRAPHY, 69, 2, 277, 283, SPRINGER, Apr. 2013, [Peer-reviewed], [Lead author, Last author, Corresponding author], [International Magazine]
English, Scientific journal, Hydrographic data measured for 50 years along Line P between the North American west coast and mid Gulf of Alaska as well as data from profiling float observations were analyzed to study the formation and variation of temperature inversions in the eastern subarctic North Pacific. Remarkable decadal to inter-decadal variation was observed in the magnitude of temperature inversions. This variation was mostly attributed to the variation of southward Ekman transport, eastward geostrophic transport, and surface cooling.

Water column iron dynamics in the subarctic North Pacific Ocean and the Bering Sea
Ren Uchida, Kenshi Kuma, Aya Omata, Satoko Ishikawa, Nanako Hioki, Hiromichi Ueno, Yutaka Isoda, Keiichiro Sakaoka, Yoshihiko Kamei, Shohgo Takagi
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 118, 3, 1257, 1271, AMER GEOPHYSICAL UNION, Mar. 2013, [Peer-reviewed], [International Magazine]
English, Scientific journal, We measured water-column iron concentrations from west to east along 47 degrees N in the subarctic North Pacific, and in the Bering Sea. In the North Pacific dissolved Fe (D-Fe) showed surface depletion, mid-depth maxima at 1000-1500 m (west, 1.3-1.6 nM; east, 0.9-1.1 nM), and a gradual decrease with depth below 3500-4000 m depth (west, 1.1-1.4 nM; east, 0.6-0.7 nM). D-Fe and total soluble Fe (T-Fe) in deep water showed a decreasing trend eastward. The higher iron concentrations in western deep waters probably result from higher inputs of dissolved Fe through atmospheric deposition or lateral transport. In contrast, D-Fe throughout the Bering Sea showed a consistent depth regime characterized by a rapid increase with depth to mid-depths, a gradual increase with depth in intermediate water to a maximum of 1.6-1.7 nM at 1500-2250 m, and a gradual decrease with depth to 1.3-1.4 nM at 3700 m. Higher iron concentrations and deeper D-Fe maxima in the Bering Sea are likely due to higher biological productivity and greater and deeper D-Fe input from the decomposition of sinking particulate organic matter in deep water. We suggest that the higher concentrations and deeper input of D-Fe as well as PO4 and humic-type fluorescent dissolved organic matter in the Bering Sea probably results from the longer time for the accumulation of decomposition products resulting from iron supply from the organic-rich downslope sediment along the steep continental slopes and slow replacement of the deep water in the Bering Sea Basin.

Lagrangian ensemble model of Copepoda (Neocalanus cristatus) in the northwestern subarctic Pacific
Takeshi Terui, Michio J. Kishi, Hiromichi Ueno
JOURNAL OF OCEANOGRAPHY, 68, 5, 727, 741, SPRINGER, Oct. 2012, [Peer-reviewed], [International Magazine]
English, Scientific journal, A Lagrangian ensemble model describing the population dynamics of Neocalanus cristatus was developed. To describe the ecology of N. cristatus, life stage must be included in the model. For this purpose, a new zooplankton compartment, divided into nine life stages, was added to the North Pacific ecosystem model for understanding regional oceanography. In addition, we introduced Lagrangian particles for the copepod population. Each Lagrangian particle represented a population of the same cohort of copepods with information on representative age, developmental stage, growth rate, structural weight, and food satiation. The new model revealed that surviving cohorts are only matched with the phytoplankton bloom after the nauplii stages. The model showed that the existing phytoplankton concentration when copepodites of N. cristatus appear in the surface water determines the development pattern of copepodite stages. The timing of the seasonal phytoplankton bloom depends on climate change, and a sensitivity analysis showed that the multiple spawning strategy through time has an important role in matching the unstable seasonal bloom cycle on a daily basis. The model including the cohorts can collaborate closely with weekly or monthly observations to reveal the rapid response of the marine ecosystem.

Modification of a Kenai eddy along the Alaskan Stream
UENO Hiromichi, YASUDA Ichiro, ITOH Sachihiko, ONISHI Hiroji, HIROE Yutaka, SUGA Toshio, OKA Eitarou
J Geophys Res, 117, C8, C08032-C08032-11, Blackwell Publishing Ltd, Aug. 2012, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal, A Kenai eddy was studied through analyses of satellite altimeter data and hydrographic data from shipboard and Argo float observations. This eddy formed in December 2006 south of the Kenai Peninsula and propagated southwestward along the Alaskan Stream. The eddy held horizontally uniform warm core water in January 2007. In late winter 2007, this core water was cooled from the top and a subsurface temperature maximum was formed around 26.5. Two years later in summer 2009, warm and low-dissolved-oxygen (low-DO) water characterized by a temperature maximum around 26.5 was observed again in the eddy core and was likely the remnant of original core water. At the same time, cold and high-DO water intrusions occurred in the eddy core, suggesting that strong modification of core water was ongoing. After summer 2009, the core water was fully changed through interaction with another eddy. © 2012. American Geophysical Union. All Rights Reserved.

Rhizoplegma boreale (Radiolaria): A tracer for mesoscale eddies from coastal areas
Takahito Ikenoue, Hiromichi Ueno, Kozo Takahashi
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 117, C4, C04001-C04001, AMER GEOPHYSICAL UNION, Apr. 2012, [Peer-reviewed], [International Magazine]
English, Scientific journal, The impact of mesoscale eddies on the production of radiolarian species Rhizoplegma boreale in the central subarctic Pacific was investigated through analysis of sinking particle fluxes collected using sediment-trap and altimetry data from satellite observations. Altimetry observations provided the locations of mesoscale eddies in time and space and indicated that mesoscale eddies propagating around sediment trap Station SA were closely related to the high R. boreale fluxes at the station. The mesoscale eddies likely provided the deep-sea region of the central subarctic Pacific with coastal nutrient-rich waters derived from the region around the Aleutian Islands, and influenced the productivity of microzooplankton groups at Station SA.

おしょろ丸北洋航海における海洋物理観測
上野洋路, 大西広二
月刊海洋, 44, 12, 2012

Kenai渦の変質過程（潮汐混合とオホーツク海・ベーリング海の物理・化学・生物過程―白鳳丸KH09‐4航海・おしょろ丸・クロモフ2006/2007シンセシス）
上野洋路, 安田一郎, 伊藤幸彦, 大西広二, 廣江豊, 廣江豊, 須賀利雄, 須賀利雄, 岡英太郎
月刊海洋, 43, 12, 756, 762, Dec. 2011, [Lead author, Corresponding author], [Domestic magazines]
Japanese

Vertical segregation within four grazing copepods in the Oyashio region during early spring
Ken-Ichi Sato, Atsushi Yamaguchi, Hiromichi Ueno, Tsutomu Ikeda
JOURNAL OF PLANKTON RESEARCH, 33, 8, 1230, 1238, OXFORD UNIV PRESS, Aug. 2011, [Peer-reviewed], [International Magazine]
English, Scientific journal, Fine-scale vertical distribution patterns of the calanoid copepods Neocalanus flemingeri, Neocalanus cristatus, Eucalanus bungii and Metridia pacifica were studied by stratified sampling (9 strata between 0 and 1000 m) with a vertical multiple plankton sampler (VMPS) every 3 h for 24 h during 21-22 March 2005 in the Oyashio region. Most C1-C5 stages of N. flemingeri and N. cristatus occurred in the 30-90 m and 70-200 m strata, respectively, both by day and night. Irrespective of day and night, C3-C6 E. bungii were distributed broadly in the 200-430 m stratum (C5 inhabiting the shallowest layer). Thus, these three copepods exhibited vertical partitioning of their habitats in the upper layers. The C1-C6 of M. pacifica were distributed broadly from 140 to 400 m during daytime and migrated up to the 100-180 m layer at night (except for non-migrant C1 and C6 males). The within-species zonation of copepodid stages was less marked, but older stages tended to occupy deeper zones (N. flemingeri, N. cristatus and M. pacifica) or shallower zones (E. bungii). Gut content analyses of N. flemingeri and N. cristatus revealed the predominance of diatoms in the guts of both species, but the proportion of broken cells was greater in the deep-dwelling N. cristatus than in the shallow-dwelling N. flemingeri, suggesting the importance of sinking phytoplankton aggregates as a food source for the former species.

Studies on ocean structure and variability in the subarctic North Pacific(The Paper for the 2010 Okada Prize of the Oceanographic Society of Japan)
UENO Hiromichi, Hiromichi Ueno, Faculty of Fisheries Sciences Hokkaido University
Oceanography in Japan, 19, 6, 301, 315, 日本海洋学会, 05 Nov. 2010
Japanese, 海洋の表層-中層の循環および変動は,熱・物質の輸送交換過程を通じて気候変動や生物生産と深い関わりがある。筆者は,北太平洋亜寒帯域に存在する水温逆転構造と中規模高気圧性渦をターゲットとして,北太平洋中高緯度域の海洋循環や熱・物質輸送交換過程に関する研究を行ってきた。水温逆転構造は,亜表層から中層にかけて水温が深さとともに高くなる水温の鉛直構造のことであり,データ解析の結果,黒潮の影響を強く受けた中層水の日本東方海域からアラスカ湾北部への輸送によって亜寒帯域の水温逆転が維持されていることが示された。また,北太平洋北岸を南西向きに流れるアラスカンストリーム域に存在する高気圧性渦を調べた結果,渦が亜寒帯域中西部の水温塩分場および生物生産に大きな影響を与えていることが示された。Surface to intermediate water circulation is related to the climate and biological production through heat/material transports and exchanges. The author has been studying ocean circulation and heat/material transports and exchanges, targeting temperature inversions (temperature increments with depth) and mesoscale eddies in the subarctic North Pacific. Temperature inversions are studied through analyses of climatological and individual oceanic data, and are indicated to be maintained by warm and saline intermediate-water transport from the area east of Japan to the northern Gulf of Alaska. Mesoscale eddies in the Alaskan Stream are studied through satellite and profiling float data analyses, and are revealed to have a significant impact on temperature/salinity fields and biological production in the western and central subarctic North Pacfic.

Studies on ocean structure and variability in the subarctic North Pacific
UENO HIROMICHI
海の研究, 19, 6, 301, 315, 05 Nov. 2010, [Peer-reviewed], [Lead author, Corresponding author], [Domestic magazines]
Japanese

The effect of climate change on the growth of Japanese chum salmon (Oncorhynchus keta) using a bioenergetics model coupled with a three-dimensional lower trophic ecosystem model (NEMURO)
Michio J. Kishi, Masahide Kaeriyama, Hiromichi Ueno, Yasuko Kamezawa
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 57, 13-14, 1257, 1265, PERGAMON-ELSEVIER SCIENCE LTD, Jul. 2010, [Peer-reviewed], [International Magazine]
English, Scientific journal, From the 1970s to 1990s, a reduction in the body size of Japanese chum salmon (Oncorhynchus keta) was observed. To investigate this body size reduction in the North Pacific, we developed a bioenergetics model for chum salmon coupled with the results from a lower trophic ecosystem model embedded into a three-dimensional global model. In the bioenergetics model, respiration and consumption terms are assumed to be functions of water temperature and prey zooplankton density, which are the determining factors of the reduction of body size. The model reproduced the body size of the 1972 and 1991 year classes of chum salmon. The reproduced body size of the 1972 year class was larger than that of 1991 year class, and this result agrees with observations from the Bering Sea. Our model also reproduced the body size trend from 1970 to 2000. The prey density, especially in the eastern North Pacific, had a greater influence on the change of body size than did the SST. This suggests that the size reduction of Japanese chum salmon in the 1990s was partly affected by changes in prey zooplankton density. In the context of the global warming scenario, we discuss changes in the migration route of chum salmon and predict that the population of Japanese chum salmon experience significant declines over this century. (C) 2010 Elsevier Ltd. All rights reserved.

Impact of Alaskan Stream Eddies on Chlorophyll Distribution in the North Pacific
Hiromichi Ueno, William R. Crawford, Hiroji Onishi
JOURNAL OF OCEANOGRAPHY, 66, 3, 319, 328, SPRINGER, Jun. 2010, [Peer-reviewed], [Lead author, Last author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, The impact of the Alaskan Stream (AS) eddies on the chlorophyll a (chl-a) distribution in the central subarctic North Pacific was investigated through analysis of chl-a and altimetry data from satellite observations. Altimetry observations provided the locations of mesoscale eddies in time and space within the maps of chlorophyll distributions. The climatological chl-a distributions averaged in the area and time showing presence of AS eddies suggested that AS eddies contributed significantly to the chl-a distribution in the deep-sea region of the subarctic North Pacific. The chl-a distribution was closely related to the AS eddies regardless of whether the eddy was located in or detached from the AS. A combination of two or three AS eddies sometimes formed high chl-a concentration belts that injected chlorophyll and coastal nutrient-rich waters southward from the Aleutian Islands far into the deep-sea region of the subarctic North Pacific. These results indicate that chl-a distribution in the central subarctic North Pacific was strongly impacted by AS eddies.

Anticyclonic Eddies in the Alaskan Stream
Hiromichi Ueno, Howard J. Freeland, William R. Crawford, Hiroji Onishi, Eitarou Oka, Kanako Sato, Toshio Suga
JOURNAL OF PHYSICAL OCEANOGRAPHY, 39, 4, 934, 951, AMER METEOROLOGICAL SOC, Apr. 2009, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, Anticyclonic eddies propagating southwestward in the Alaskan Stream (AS) were investigated through analysis of altimetry data from satellite observations during 1992-2006 and hydrographic data from profiling float observations during 2001-06. Fifteen long-lived eddies were identified and categorized based on their area of first appearance. Three eddies were present at the beginning of the satellite observations; another three formed in the eastern Gulf of Alaska off Sitka, Alaska; and four were first detected at the head of the Gulf of Alaska near Yakutat, Alaska. The other five eddies formed along the AS between 157 degrees and 169 degrees W, and were named AS eddies. While the eddies that formed in the Gulf of Alaska mainly decayed before exiting the Gulf of Alaska, the AS eddies mostly crossed the 180 degrees meridian and reached the western subarctic gyre. Four of five AS eddies formed under negative or weakly positive wind stress curls, which possibly caused AS separation from the coast. Comparison of eddy propagation speeds in the AS with the bottom slope showed that eddies propagated faster over steeper slopes, although eddy speeds were slower than those predicted by the topographic planetary wave dispersion relation. An AS eddy was observed by profiling floats in the western subarctic gyre after it detached from the AS. Intermediate-layer water near the eddy center had low potential vorticity compared with the surrounding water, suggesting that AS eddies provided the western subarctic gyre with water just south of the Aleutian Islands.

Argoの現状と課題―海洋学の基盤としてのArgo―表層水塊および成層構造の時空間変動に関する研究の進展と今後の展開
須賀利雄, 須賀利雄, 上野洋路, 大西広二, 林和彦, 齋藤寛子, 鋤柄千穂, 遠山勝也
月刊海洋, 39, 7, 450, 455, 海洋出版, 01 Jul. 2007, [Domestic magazines]
Japanese

Formation and variation of temperature inversions in the eastern subarctic North Pacific
Hiromichi Ueno, Eitarou Oka, Toshio Suga, Hiroji Onishi, Dean Roemmich
GEOPHYSICAL RESEARCH LETTERS, 34, 5, L05603-L05603, AMER GEOPHYSICAL UNION, Mar. 2007, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, Hydrographic data from profiling float observations for 2001 - 2005 and from expendable bathythermograph observations for 1993 - 2005 were analyzed to study the formation and variation of temperature inversions (T-inversions) in the eastern subarctic North Pacific ( SNP). The formation and variation of T-inversions differed significantly between the northern and southern regions of the eastern SNP. In the northern region, the temperature minimum (T-min) at the top of T-inversions outcropped to the sea surface and was cooled in the mixed layer nearly every winter. This process caused a seasonal cycle in the magnitude of T-inversions (DT), with a maximum in winter. In the southern region, the winter T-min outcropped relatively infrequently and the DT did not exhibit a significant maximum in winter during most years. The T-min in the southern region was likely to outcrop upstream near the date line roughly one year earlier and was then advected to the southern region.

Temperature inversions in the subarctic North Pacific
H Ueno, Yasuda, I
JOURNAL OF PHYSICAL OCEANOGRAPHY, 35, 12, 2444, 2456, AMER METEOROLOGICAL SOC, Dec. 2005, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal, Hydrographic data from the World Ocean Database 2001 and Argo profiling floats were analyzed to study temperature inversions in the subarctic North Pacific Ocean. The frequency distribution of temperature inversions [F(t-inv)] at a resolution of 1 degrees ( latitude) x 3 degrees ( longitude) was calculated. Temperature inversions seldom occurred around 50 degrees N in the eastern subarctic North Pacific but were more common in the northern Gulf of Alaska and the southeastern subarctic North Pacific (42 degrees-48 degrees N, 140 degrees-170 degrees W). Large temperature inversions occurred throughout the year in the western and central subarctic North Pacific ( north of 42 N and west of 180) except near the Aleutian and Kuril Islands. Near those islands, F(t-inv) was characterized by pronounced seasonal variations forced by surface heating/cooling and strong tidal mixing.

Seasonal and interannual variability of temperature inversions in the subarctic North Pacific
H Ueno, E Oka, T Suga, H Onishi
GEOPHYSICAL RESEARCH LETTERS, 32, 20, L20603-L20603, AMER GEOPHYSICAL UNION, Oct. 2005, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal

Intermediate water circulation in the North Pacific subarctic and northern subtropical regions
H Ueno, Yasuda, I
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 108, C11, AMER GEOPHYSICAL UNION, Nov. 2003, [Peer-reviewed], [International Magazine]
English, Scientific journal, [1] The intermediate water circulation in the North Pacific subarctic and northern subtropical regions is investigated through inverse analysis, focusing on the volume and heat transports from the subtropical to the subarctic regions. The inverse method we adopted is a hybrid method of beta- spiral and box inverse methods which permits diapycnal flux. The isopycnal velocities estimated through the inverse analysis are mostly consistent with the oxygen distribution and support the hypothesis that warm and saline intermediate water is transported from the transition domain east of Japan to the northern Gulf of Alaska. The northward volume transport across 46 degrees N between 158 degrees E and 130 degrees W is estimated to be - 0.2 to 5.3 Sv in the density range of 26.7 - 27.2sigma(theta). The upward diapycnal transports in the open subarctic North Pacific ( region N) across 26.7 and 27.2sq isopycnal surfaces are estimated to be 0.2 to 1.5 Sv and - 0.2 to 0.9 Sv, respectively. Part of the water transported upward across 26.7sigma(theta) might outcrop and be carried to the subtropical region by the southward Ekman drift. Through the examination of heat balance of the intermediate layer in the subarctic region, it is suggested quantitatively that the intermediate heat transport from the south plays an essential role in maintaining the heat of the mesothermal waters in the subarctic region.

Warm and saline water transport to the North Pacific subarctic region: World Ocean Circulation Experiment and Subarctic Gyre Experiment data analysis
H Ueno, Yasuda, I
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 106, C10, 22131, 22141, AMER GEOPHYSICAL UNION, Oct. 2001, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal, A warm and saline water transport to the North Pacific subarctic region which could feed the mesothermal (intermediate temperature maximum) water is investigated through the analysis of World Ocean Circulation Experiment and Subarctic Gyre Experiment hydrographic data. The analysis of individual cruise data supports the hypothesis that warm and saline water is transported from the area east of Japan, to the Gulf of Alaska and also indicates that the isopycnal mixing is active in the area east of 165 degreesE. The transport route obtained from individual cruise data mostly agrees with that based on climatological data. As a whole, isopycnal potential temperature and potential vorticity are conserved along the transport route using both the climatological and individual data excepting that the potential vorticity at 26.8 sigma (theta) rapidly increases along streamlines in the Gulf of Alaska when the climatological data are used. This discrepancy might be attributed to the existence of the strong potential vorticity front in the Gulf of Alaska and excessive smoothing in the climatological data.

Distribution and formation of the mesothermal structure (temperature inversions)in the North Pacific subarctic region
H Ueno, Yasuda, I
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 105, C7, 16885, 16897, AMER GEOPHYSICAL UNION, Jul. 2000, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
English, Scientific journal, The distribution and formation of mesothermal structure (temperature inversions) in the North Pacific subarctic region are investigated through analysis of climatological hydrographic data. It is suggested that the heat and salt that maintain the mesothermal water and thus the halocline in the density range of 26.7-27.2 sigma(theta) are transported as a cross-gyre flow from the transition domain just east of Japan, where the waters an influenced by the subtropical gyre water mass, to the eastern subarctic region. Along the transport route the isopycnal potential temperature and thus salinity are well conserved. In the western subarctic gyre, the Bering Sea, and the northern Gulf of Alaska, the temperature reaches its minimum at the surface in winter and the areal coverage agrees well with the distribution of the mesothermal structure. In the southeastern part of the zonally distributed mesothermal structure in the area of 170 degrees E-150 degrees W and 45 degrees-50 degrees N, where the winter sea surface temperature is higher than that in the deeper layer, dichothermal water is formed by subsurface intrusion of the low-temperature and low-salinity water that outcropped in the previous winter over the warm and saline water transported from the transition domain.

海をまるごとサイエンス : 水産科学の世界へようこそ
海に魅せられた北大の研究者たち, 海面の凸凹は海の天気図
海文堂出版, 2018, 9784303800017, 127p, Japanese

図説地球環境の事典　　　　　　　　　　　　　　　
上野洋路, 北太平洋亜寒帯循環
朝倉書店, Sep. 2013, [Contributor]

自然及び人為ストレス下の北極海洋生態系変動評価　　　　　　　　　　　　　　　
平田貴文, 平田貴文, ALABIA Irene, MOLINOS Jorge Garcia, 大塚夏彦, 上野洋路, 渡邉英嗣
日本海洋学会大会講演要旨集(Web), 2023
2023 - 2023

冬季塩分躍層の全球分布と経年変動　　　　　　　　　　　　　　　
上野洋路, 小田正人, 安井桂, 土橋稜, 三寺史夫
日本海洋学会大会講演要旨集(Web), 2022
2022 - 2022

北極海ノースウィンド深海平原における海氷厚の季節変動　　　　　　　　　　　　　　　
上野威, 上野洋路, 上野洋路, 伊東素代, 渡邉英嗣, 小野寺丈尚太郎, 川口悠介, 藤尾伸三, 守家衣利加, 深町康
日本海洋学会大会講演要旨集(Web), 2022
2022 - 2022

広域的な環境DNA解析によって捉えた魚類群集と海洋大規模循環構造との対応　　　　　　　　　　　　　　　
川上達也, 山崎彩, 上野洋路, 兵藤晋, 笠井亮秀
水産海洋学会研究発表大会講演要旨集, 2021
2021 - 2021

黒潮親潮混合域における高気圧性渦の一次生産と魚類分布への影響　　　　　　　　　　　　　　　
土橋稜, 上野洋路, 加藤陸, 閻乃筝, 向井徹, 安間洋樹, 野村大樹, 伊藤幸彦, 笠井亮秀
日本水産学会大会講演要旨集(CD-ROM), 2021
2021 - 2021

2017・2018年北部ベーリング海における成層強度の時空間変動とその要因　　　　　　　　　　　　　　　
上野洋路, 小松瑞紀, 吉兆千一, 土橋稜, 村松美幌, 村松美幌, 阿部泰人, 今井圭理, 大木淳之, 平譯享
日本海洋学会大会講演要旨集, 2020
2020 - 2020

The Oceanographic Society of Japan (JOS) School Visit Program　　　　　　　　　　　　　　　
森岡優志, 藤井直紀, 上野洋路, 仙田明大, 帰山秀樹, 安中さやか
日本地球惑星科学連合大会予稿集(Web), 2020
2020 - 2020

環境変動がサケに与える影響評価と課題 海洋変動がサケに及ぼす影響:北極海における潜在的なサケ生息域分布
上野洋路, 尹錫鎭, 渡邉英嗣, 岸道郎
日本水産学会大会講演要旨集, 26 Mar. 2018, Japanese
26 Mar. 2018 - 26 Mar. 2018

Aquariusが捉えた降水後のeddy stirring
阿部泰人, 阿部泰人, 阿部泰人, 江淵直人, 上野洋路, 石山宙夢, 松村義正, 松村義正
日本海洋学会大会講演要旨集, Sep. 2017, Japanese
Sep. 2017 - Sep. 2017

チャクチ海における熱収支の経年変動
塚田雄志郎, 上野洋路, 太田直紀, 伊東素代, 渡邉英嗣, 菊地隆, 西野茂人, 溝端浩平
日本海洋学会大会講演要旨集, Sep. 2017, Japanese
Sep. 2017 - Sep. 2017

日本海洋学会講師派遣事業「海の出前授業」の取り組み
森岡優志, 上野洋路, 藤井直紀, 小埜恒夫, 藤井賢彦, 轡田邦夫, 原田尚美
日本海洋学会大会講演要旨集, Sep. 2017, Japanese
Sep. 2017 - Sep. 2017

ベーリング海峡移流熱がチャクチ海の太陽放射加熱に与える影響
塚田雄志郎, 上野洋路, 太田直紀, 伊東素代, 渡邉英嗣, 菊地隆, 西野茂人, 溝端浩平
日本海洋学会大会講演要旨集, Aug. 2016, Japanese
Aug. 2016 - Aug. 2016

西部アリューシャン列島南岸における中規模高気圧性渦の低次生物生産への影響
齋藤類, 安田一郎, 小松幸生, 石山宙夢, 上野洋路
日本海洋学会大会講演要旨集, Mar. 2016, Japanese
Mar. 2016 - Mar. 2016

全球における海洋中規模渦の合併と分裂:Okubo‐Weiss methodとSLA‐based methodとの比較
石山宙夢, 上野洋路, 稲津將, 伊藤幸彦
日本海洋学会大会講演要旨集, Mar. 2016, Japanese
Mar. 2016 - Mar. 2016

アリューシャン渦の形成・伝播・相互作用
上野洋路, 石山宙夢, 稲津將
日本海洋学会大会講演要旨集, Mar. 2016, Japanese
Mar. 2016 - Mar. 2016

チャクチ海における成層強度の時空間変動とその要因
大額実咲, 上野洋路, 伊東素代, 菊地隆, 西野茂人, 渡邉英嗣, 平譯亨, 川合美千代, 溝端浩平
日本海洋学会大会講演要旨集, Mar. 2016, Japanese
Mar. 2016 - Mar. 2016

Tidal mixing and dissolved iron transport along the shelf break of the southeastern Bering Sea
田中 雄大, 安田 一郎, 久万 健志, 西岡 純, 田中 祐希, 大西 広二, 上野 洋路, 増島 雅親
海洋. 号外 = Kaiyo monthly : カラー版, 2016, 海洋出版, Japanese
2016 - 2016

おしょろ丸東経155度定線で観察される移行領域モード水水温の長期変動特性
杉本周作, 上野洋路, 星直樹
日本海洋学会大会講演要旨集, 10 Sep. 2015, Japanese
10 Sep. 2015 - 10 Sep. 2015

アリューシャン渦におけるクロロフィル分布の時間変化
齋藤類, 安田一郎, 小松幸生, 石山宙夢, 上野洋路
日本海洋学会大会講演要旨集, 10 Sep. 2015, Japanese
10 Sep. 2015 - 10 Sep. 2015

アリューシャン渦の海表面における一次生産への影響
SAITO RUI, YASUDA ICHIRO, KOMATSU KOSEI, ISHIYAMA HIROMU, UENO HIROMICHI
日本海洋学会大会講演要旨集, Mar. 2015, Japanese

渦位フロントから見た北太平洋中高緯度における中層循環の熱輸送量の変動
OE MITSUHO, UENO HIROMICHI
日本海洋学会大会講演要旨集, Mar. 2015, Japanese

チャクチ海におけるカイアシ類の空間分布に影響を及ぼす海洋環境要因
SASAKI YUKO, MATSUNO KOHEI, ONUKA MISAKI, UENO HIROMICHI, WAGA HISATOMO, YAMAGUCHI ATSUSHI, HIRAWAKE TOORU, WATANUKI YUTAKA
日本海洋学会大会講演要旨集, Mar. 2015, Japanese

チャクチ海における成層強度の時空間変動とその要因
大額実咲, 上野洋路, 伊東素代, 菊地隆, 西野茂人, 渡邉英嗣, 平譯亨, 川合美千代, 溝端浩平
極域科学シンポジウム講演予稿集(CD-ROM), 2015, Japanese
2015 - 2015

チャクチ海の熱バランス
OTA NAOKI, UENO HIROMICHI, ITO MOTOYO, KIKUCHI TAKASHI, NISHINO SHIGETO, WATANABE HIDETSUGU, MIZOHATA KOHEI
日本海洋学会大会講演要旨集, 01 Sep. 2014, Japanese

チャクチ海における成層強度の時空間変動
ONUKA MISAKI, UENO HIROMICHI, ITO MOTOYO, KIKUCHI TAKASHI, HIRAWAKE TOORU, NISHINO SHIGETO, WATANABE HIDETSUGU, MIZOHATA KOHEI
日本海洋学会大会講演要旨集, 01 Sep. 2014, Japanese

伝播経路が異なるアリューシャン渦における物理環境の鉛直分布の比較
SAITO RUI, YASUDA ICHIRO, KOMATSU KOSEI, ISHIYAMA HIROMU, UENO HIROMICHI, ONISHI HIROJI
日本海洋学会大会講演要旨集, 01 Sep. 2014, Japanese

水温逆転層が混合層熱収支に与える影響の経年変動解析
OHARA SAKAE, UENO HIROMICHI, TANIHIRA YOSUKE, HOSODA SHIGEKI
日本海洋学会大会講演要旨集, 01 Sep. 2014, Japanese

全球における海洋中規模渦の合併と分裂
ISHIYAMA HIROMU, UENO HIROMICHI, INATSU MASARU, ITO YUKIHIKO
日本海洋学会大会講演要旨集, 01 Sep. 2014, Japanese

北太平洋東部亜熱帯域における水温逆転構造―2種類の形成メカニズム―
手倉森司, 上野洋路
日本海洋学会大会講演要旨集, 10 Mar. 2014, Japanese

ベーリング海プリビロフ峡谷の陸棚縁辺周辺における流動・鉛直混合強度の集中観測
田中雄大, 安田一郎, 大西広二, 上野洋路, 増島雅親
日本海洋学会大会講演要旨集, 10 Mar. 2014, Japanese

アリューシャン渦の水塊構造と特性
齋藤類, 安田一郎, 小松幸生, 石山宙夢, 上野洋路, 大西広二, 山口篤
日本海洋学会大会講演要旨集, 10 Mar. 2014, Japanese

Distribution and seasonal variation of halocline in the world ocean
UENO HIROMICHI, YASUI KATSURA
International Symposium on Okhotsk Sea and Sea Ice (Mombetsu), 15 Feb. 2014, English

チャクチ海における動物プランクトン密度の空間変化に影響を及ぼす海洋環境要因
佐々木裕子, 松野孝平, 和賀久朋, 大額実咲, 山口篤, 上野洋路, 平譯享, 綿貫豊
極域科学シンポジウム講演予稿集(CD-ROM), 2014, Japanese
2014 - 2014

Decadal variation of temperature inversions along Line P　　　　　　　　　　　　　　　
Hiromichi Ueno
North Pacific Marine Science Organization (PICES) 2013 Annual Meeting, Oct. 2013, English, Poster presentation
[International presentation]

Influence of Aleutian eddies on calanoid copepods south of the western Aleutian Islands during summer　　　　　　　　　　　　　　　
Saito, R, A. Yamaguchi, H. Ueno, H. Ishiyama, H. Onishi, I. Imai, I. Yasuda
North Pacific Marine Science Organization (PICES) 2013 Annual Meeting, Oct. 2013, English, Oral presentation
[International presentation]

Estimating potential habitat for chum salmon (Oncorhynchusketa) in the Western Arctic using a bioenergetics model coupled with a three-dimensional lower trophic ecosystem model　　　　　　　　　　　　　　　
Yoon, S, E. Watanabe, H. Ueno, M. J. Kishi
North Pacific Marine Science Organization (PICES) 2013 Annual Meeting, Oct. 2013, English, Oral presentation
[International presentation]

夏季の西部アリューシャン列島南岸域における中規模高気圧性渦が動物プランクトンの分布に与える影響
齋藤類, 山口篤, 安田一郎, 上野洋路, 石山宙夢, 大西広二, 今井一郎
日本ベントス学会・日本プランクトン学会合同大会講演要旨集, 26 Sep. 2013, Japanese

北太平洋における海洋中規模渦の合併と分裂
石山宙夢, 上野洋路, 稲津將
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

北太平洋中高緯度域における渦位フロントの経年変動―Argoデータを用いた解析―
大江光穂, 上野洋路
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

北太平洋中高緯度域における混合層熱収支
谷平洋介, 上野洋路, 細田滋毅
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

夏季のアラスカンストリーム流域における大型カラヌス目カイアシ類の空間分布
齋藤類, 山口篤, 安田一郎, 上野洋路, 大西広二, 今井一郎
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

北太平洋東部亜熱帯域における水温逆転構造の形成過程
手倉森司, 上野洋路
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

全球塩分躍層の季節変動
安井桂, 上野洋路
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

チャクチ海における太陽放射加熱の時空間変動
太田直紀, 上野洋路, 伊東素代, 菊地隆
日本海洋学会大会講演要旨集, 30 Aug. 2013, Japanese

北海道からシロザケを何尾放流したらよいか,をモデルで考える
岸道郎, 三輪剛, 上野洋路, 永沢亨
水産海洋学会研究発表大会講演要旨集, 2013, Japanese

Formation and modification of a Kenai eddy along the Alaskan Stream　　　　　　　　　　　　　　　
Ueno, H, I. Yasuda, S. Itoh, H. Onishi, Y. Hiroe, T. Suga, E. Oka
2012 AGU Fall Meeting, Dec. 2012, English, Poster presentation
[International presentation]

Distribution and formation of halocline in the world ocean　　　　　　　　　　　　　　　
Yasui, K, H. Ueno
2012 AGU Fall Meeting, Dec. 2012, English, Poster presentation
[International presentation]

Formation and propagation of the Aleutian eddy　　　　　　　　　　　　　　　
Ishiyama, H, H. Ueno and, M. Inatsu
2012 AGU Fall Meeting, Dec. 2012, English, Poster presentation
[International presentation]

Interannual variations in the zooplankton community in the Alaskan Stream region during the summer of 2004-2010　　　　　　　　　　　　　　　
R. Saito, A. Yamaguchi, H. Ueno, H. Onishi, I. Imai
North Pacific Marine Science Organization (PICES) 2012 Annual Meeting, Oct. 2012, English
[International presentation]

釧路沖高気圧渦の再生:暖水塊から冷水塊へ
伊藤幸彦, 安田一郎, 上野洋路, 須賀利雄, 須賀利雄
日本海洋学会大会講演要旨集, 01 Sep. 2012, Japanese

北太平洋東部亜熱帯域における水温逆転構造
手倉森司, 上野洋路
日本海洋学会大会講演要旨集, 01 Sep. 2012, Japanese

北太平洋中高緯度域における渦位フロントの経年変動
大江光穂, 上野洋路
日本海洋学会大会講演要旨集, 01 Sep. 2012, Japanese

北太平洋中高緯度域における中規模渦とクロロフィルの関係
上野洋路, 大江光穂, 嘉山雄大, 加藤尋樹
日本海洋学会大会講演要旨集, 01 Sep. 2012, Japanese

おしょろ丸北洋航海における海洋物理観測　　　　　　　　　　　　　　　
上野洋路, 大西広二
東京大学海洋研究所共同利用研究集会「アルゴ時代の海洋物理船舶観測」, Aug. 2012, Japanese, Oral presentation
[Domestic Conference]

Zooplankton community in the Alaskan Stream water during summer of 2010: the influence of mesoscale eddies　　　　　　　　　　　　　　　
R. Saito, A. Yamaguchi, H. Ueno, H. Onishi, I. Imai
2012 ASLO Aquatic Sciences Meeting, Jul. 2012, English
[International presentation]

2010年夏季のアラスカンストリーム海域における動物プランクトン群集:中規模渦の影響
齋藤類, 山口篤, 上野洋路, 大西広二, 今井一郎
日本海洋学会大会講演要旨集, 13 Mar. 2012, Japanese

Modification of a Kenai eddy along the Alaskan Stream, Ocean Science Meeting　　　　　　　　　　　　　　　
Ueno, H, I. Yasuda, S. Itoh, H. Onishi, Y. Hiroe, T. Suga, E. Oka
2012 Ocean Science Meeting, Feb. 2012, English
[International presentation]

全球塩分躍層の分布と形成
安井桂, 上野洋路
日本海洋学会大会講演要旨集, 01 Sep. 2011, Japanese

アリューシャン渦の形成及び伝播特性
石山宙夢, 上野洋路, 稲津將
日本海洋学会大会講演要旨集, 01 Sep. 2011, Japanese

アラスカ湾における水温逆転構造の長期変動
上野洋路, 松永翔太
日本海洋学会大会講演要旨集, 01 Sep. 2011, Japanese

Kenai渦の変質過程
上野洋路, 安田一郎, 伊藤幸彦, 大西広二, 廣江豊, 廣江豊, 須賀利雄, 須賀利雄, 岡英太郎
日本海洋学会大会講演要旨集, 14 Mar. 2011, Japanese

Observations of a Kenai eddy along the Alaskan Stream south of the Aleutian Islands　　　　　　　　　　　　　　　
Ueno, H, H. Onishi, S. Itoh, I. Yasuda, Y. Hiroe, T. Suga, E. Oka
North Pacific Marine Science Organization (PICES) 2010 Annual Meeting, Oct. 2010, English, Oral presentation
[International presentation]

Kenai渦の物理・化学・生物過程　　　　　　　　　　　　　　　
上野洋路, 安田一郎, 伊藤幸彦, 大西広二, 廣江豊, 須賀利雄, 岡英太郎
東京大学大気海洋研究所共同利用研究集会 潮汐混合とオホーツク海・ベーリング海の物理・化学・生物過程: 白鳳丸KH09-4航海・おしょろ丸・クロモフ2006/2007シンセシス, Oct. 2010, Japanese, Oral presentation
[Domestic Conference]

2010年度日本海洋学会岡田賞受賞記念講演-北太平洋亜寒帯の海洋構造と動態の解析研究-　　　　　　　　　　　　　　　
上野洋路
2010年度日本海洋学会春季大会, Mar. 2010, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

アラスカンストリームを西進する高気圧性渦:Yakutat06
上野洋路, 大西広二, 伊藤幸彦, 安田一郎, 佐藤佳奈子
日本海洋学会大会講演要旨集, 11 Sep. 2009, Japanese

北太平洋亜寒帯循環域における海面高度の経年変動
牧原宏利, 大西広二, 上野洋路
日本海洋学会大会講演要旨集, 23 Mar. 2009, Japanese

北太平洋亜熱帯循環北部サブダクション領域における水塊変動の要因
須賀利雄, 佐藤佳奈子, 細田滋毅, 上野洋路, 四竃信行, 小林大洋, 岩坂直人, 岩坂直人, 岡英太郎, 岡英太郎, 野中正見
日本海洋学会大会講演要旨集, 08 Sep. 2008, Japanese

アラスカンストリーム渦のクロロフィル分布への影響
上野洋路, CRAWFORD William R, 大西広二
日本海洋学会大会講演要旨集, 08 Sep. 2008, Japanese

アラスカンストリームを西進する高気圧性渦
上野洋路, FREELAND H, CRAWFORD W, 大西広二, 岡英太郎, 岡英太郎, 佐藤佳奈子, 須賀利雄, 須賀利雄
日本海洋学会大会講演要旨集, 14 Mar. 2008, Japanese

北太平洋東部亜寒帯域水温逆転の経年変動
上野洋路, 岡英太郎, 須賀利雄, 須賀利雄, 大西広二, ROEMMICH Dean
日本海洋学会大会講演要旨集, 15 Mar. 2006, Japanese

Argoデータによるアラスカ湾の水温逆転構造と暖水渦(2)
大西広二, 上野洋路, 岡英太郎, 須賀利雄, 須賀利雄
日本海洋学会大会講演要旨集, 15 Mar. 2006, Japanese

北太平洋亜寒帯域水温逆転の経年変動
上野洋路, 岡英太郎, 須賀利雄, 須賀利雄, 大西広二, ROEMMICH Dean
日本海洋学会大会講演要旨集, 05 Sep. 2005, Japanese

Argoデータによるアラスカ湾の水温逆転構造と暖水渦
大西広二, 橋本洋平, 岡英太郎, 上野洋路
日本海洋学会大会講演要旨集, 2005, Japanese

西部北太平洋における中層水の約20年周期変動と潮汐力の18.6年周期変動
長船哲史, 安田一郎, 建部洋晶, 上野洋路
日本海洋学会大会講演要旨集, 2005, Japanese

Argoデータを用いた北太平洋亜寒帯域水温逆転の解析
上野洋路, 岡英太郎, 細田滋毅, 小林大洋, 須賀利雄
日本海洋学会大会講演要旨集, 23 Sep. 2004, Japanese

北太平洋亜寒帯域水温逆転―WOD01を用いた詳細な解析―
上野洋路, 安田一郎
日本海洋学会大会講演要旨集, 26 Mar. 2004, Japanese

北太平洋亜寒帯域及び北部亜熱帯域の中層循環
上野洋路, 安田一郎
日本海洋学会大会講演要旨集, 27 Mar. 2003, Japanese

北太平洋亜寒帯域の中暖水形成 等密度面を横切る流れの見積り
上野洋路, 安田一郎
日本海洋学会大会講演要旨集, 22 Sep. 2001, Japanese

北太平洋亜寒帯域の中暖水(水温極大水)形成 インバース法を用いた解析
上野洋路, 安田一郎
日本海洋学会大会講演要旨集, 26 Sep. 2000, Japanese

北太平洋亜寒帯域の中暖水形成における循環境界を横切る流れの役割
上野洋路, 安田一郎
日本海洋学会大会講演要旨集, 16 Sep. 1999, Japanese

Analysis of middle-depth warm water formation in the North Pacific Ocean subarctic area.
UENO YOJI, YASUDA ICHIRO
日本海洋学会大会講演要旨集, 1998, Japanese

海洋中規模渦が炭素循環へ与える影響：北太平洋亜寒帯西部において
土橋稜, 上野洋路, May 2022 - Present, [Educational materials]

Mesoscale eddies: anticyclones and cyclones in the ocean
LASBOS Moodle, Hiromichi UENO, Miaki MURAMATSU, 02 May 2020 - Present, [Educational materials]

海洋中規模渦の高解像度観測：北太平洋西部亜寒帯域において
土橋稜, 上野洋路, May 2022, [Educational materials]

チャクチ海北東部陸棚縁辺部における太平洋夏季水の輸送
LASBOS Moodle, 村松美幌, 上野洋路, 15 Aug. 2021, [Educational materials]

北部ベーリング海の海氷分布と成層強度
LASBOS Moodle, 上野洋路, 24 Jul. 2021, [Educational materials]

The Changing Arctic Ocean: Focusing on Pacific Summer Water
LASBOS Moodle, Hiromichi UENO, Miaki MURAMATSU, 12 Dec. 2020, [Educational materials]

Spatiotemporal variation of the halocline and its impact on biological production in the North Pacific
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
01 Apr. 2018 - 31 Mar. 2021
Ueno Hiromichi
A halocline is a layer containing a strong vertical salinity gradient. In the subarctic North Pacific, the permanent halocline depth and intensity distributions corresponded to those of winter mixed layer depth and sea surface salinity, respectively, implying that the permanent halocline forms in association with winter mixing throughout the subarctic North Pacific. We also found that stratification in early summer in the northern Bering Sea was significantly weaker in 2018 than in 2017. This result is consistent with the extremely low sea-ice extent present in the winter of 2017/2018. We further investigated the distribution and interannual variation in the winter halocline in the upper layers of the world ocean. A halocline was observed in the tropics, equatorward portions of subtropical regions, the subarctic North Pacific and Southern Ocean, but was absent in the central subtropics.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 18K03736

北太平洋西部亜寒域における海洋中規模渦の物質循環・低次生態系への影響の解明
科学研究費助成事業 新学術領域研究(研究領域提案型)
01 Apr. 2016 - 31 Mar. 2018
上野 洋路
本研究では、アリューシャン列島南岸で形成され、北太平洋西部亜寒域を南西に伝播、同海域の水平、鉛直混合に重要な役割を果たすと考えられているアリューシャン渦に注目し、同渦が北太平洋西部亜寒域における生産を左右する栄養物質の循環および低次生態系への影響を理解することを目的として研究を実施した。
今年度は、2016年度おしょろ丸60日航海において実施した乱流観測および鉄濃度観測によって得られたデータについて詳しい検討を行った。本観測は、海洋中規模渦内・縁辺付近では、乱流エネルギー散逸率、鉛直拡散係数が大きく、その結果、渦内・縁辺付近に高い生物生産をもたらしているのではないかとの予測に基づいて実施したものである。しかし、解析の結果、その予測とは異なる結果が得られた。まず、乱流データ解析の結果、渦内外で鉛直拡散係数に顕著な違いはなく、一般的な外洋域の値程度であることが示された。鉄濃度に関しても、渦内外で顕著な差は観測されず、一般的な北太平洋亜寒帯外洋域の値に近いものとなっていた。これらの結果は、クロロフィル蛍光度の分布、すなわち渦内外でクロロフィル蛍光度に顕著な差は観測されなかったという観測結果と整合的であった。以上の結果から、2016年度おしょろ丸60日航海において観測した中規模高気圧性渦内・外縁部付近では、鉛直混合、さらにそれに伴う下層から有光層への鉄供給が周辺海域と同様に弱く、結果として周辺海域と比べて高いクロロフィル蛍光度が観測されなかったと考えられる。
本研究ではさらに、北太平洋西部亜寒帯全域における中規模渦の性質も検討した。その結果、アリューシャン渦形成域では、その周辺海域と比べて特に多くの渦が形成されるわけではないことが示され、当該海域では、周辺海域よりも大きくて強い渦が形成され、寿命も長いという特徴を持つことで、西部亜寒帯外洋域に大きな影響を持つことが示唆された。
日本学術振興会, 新学術領域研究(研究領域提案型), 北海道大学, 16H01584

Spatio-temporal dynamics of highly migratory top predators over ocean provinces
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
28 Jun. 2012 - 31 Mar. 2017
Kiyota Masashi, OKUDA Takehiro, KATO Yoshiki, KAERIYAMA Masahide, MURAKAMI Chisato
We promoted four study projects to understand the structure and function of ocean provinces as habitats and food environment for marine higher trophic level (HTL) organisms: 1) We developed a new clustering algorithm to classify HTL communities and estimated a community cluster maps using a machine learning technique. 2) We made Ecopath ecosystem models for the classified HTL communities, and compared their food web characteristics, estimated key species and key processes, and evaluated the impacts of commercial fisheries. 3) We analyzed the sexual differences in seasonal latitudinal migration in neon-flying squids and simulated sexual dimorphism in body size using ecosystem and bioenergetic models. 4) We estimated the primary production of each ocean province that supports the growth and migration of chum salmon released from and returning to mother rivers in Japan. Results of this study provides a novel method for quantifying the supporting service of the marine ecosystem services.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Fisheries Research and Education Agency, 24121008

Studies on mesoscale eddies in the subarctic North Pacific based on shipboard, satellite and float observations
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
01 Apr. 2010 - 31 Mar. 2014
UENO Hiromichi
Mesoscale eddies in the western and central subarctic North Pacific were studied through analyses of satellite altimeter data and data from shipboard and Argo float observations. We found that the core water of a Kenai eddy formed in December 2006 south of the Kenai Peninsula was modified by surface cooling, cold water intrusions and eddy-eddy interaction. We also found that mesoscale eddies had a significant impact on zooplankton community.
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, Principal investigator, Competitive research funding, 22740303

Characteristics of eddies in the western subarctic North Pacific and their impact on biological production
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
2008 - 2009
UENO Hiromichi
Formation and propagation of Alaskan Stream eddies and their impact on the chlorophyll a (chl-a) distribution in the western and central subarctic North Pacific were investigated through analysis of satellite data. Formation and propagation were suggested to be affected by wind stress and bottom topography, respectively. Alaskan Stream eddies contributed significantly to the chl-a distribution in the deep-sea region of the subarctic North Pacific thorough chlorophyll/nutrient-rich water transport from the Aleutian Islands to the deep-sea region of the subarctic North Pacific.
Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Japan Agency for Marine-Earth Science and Technology, Principal investigator, Competitive research funding, 20740277

北太平洋亜熱帯-亜寒帯循環系における中層水の形成と循環に関する研究
科学研究費助成事業 特別研究員奨励費
2002 - 2003
上野 洋路
本研究ではまず、昨年度に引き続きインバース法を用いて亜熱帯-亜寒帯海水交換と等密度面を横切る流れの亜寒帯域水温極大水(中暖水)への影響の定量的評価を行った。本年度は特に、誤差の評価に重点を置いた解析を行ない、亜寒帯域中暖水の熱の維持には南からの中層熱輸送が本質的な役割を果たしていることを、より定量的に示すことができた。この成果に関しては、2003年4月にフランス・ニースで開催された国際学会「欧州地球物理学会-米国地球物理学連合学会-欧州地球科学会・合同大会」および2003年7月に札幌で開催された国際学会「第23回国際測地学・地球物理学連合総会」にてポスター発表を行い、2003年11月に国際学術誌「Journal of Geophysical Research」に掲載された。
本研究では更に、北太平洋中高緯度域の亜表層・中層の水温・塩分構造の更なる理解を目指し、過去に観測された海洋データ(北太平洋中高緯度域で約80万点)の直接解析を行なった。具体的には、北太平洋亜寒帯域に特徴的な構造である水温逆転構造の存在確率分布を推定、どの海域でどの程度の水温逆転が起こっているかを定量的に議論した。その結果、例えばアリューシャン列島、千島列島沿いでは、冬季に水温逆転が形成され、季節の進行と共に極小、極大水が共に昇温するが、極小水の昇温の方が大きい為、逆転水温及び水温逆転存在確率は秋にかけて減少することが分かった。また、上記水温上昇は、海面加熱と中層における暖水供給、及び強い潮汐混合によると推察される。この結果は、国際学術誌「Journal of Geophysical Research」に投稿中であり、2004年3月27日に筑波大学で開催される2004年度日本海洋学会春季大会にて口頭発表する予定である。
日本学術振興会, 特別研究員奨励費, 東京大学, 02J08240