野村 大樹 (ノムラ ダイキ)
| 水産科学研究院 海洋生物資源科学部門 海洋環境科学分野 | 教授 |
| 北極域研究センター | 教授 |
Last Updated :2025/06/07
■研究者基本情報
プロフィール情報
北海道大学大学院水産科学研究院所属。教授。博士（環境科学）。1980年生まれ。愛知県稲沢市出身。学位取得後、国立極地研究所、ノルウェー極地研究所、北海道大学低温科学研究所、北海道大学大学院水産科学研究院、北海道大学北方生物圏フィールド科学センターを経て、現職。北極海、南極海、オホーツク海の海氷および海洋を対象とした観測研究に従事。また、海氷生成施設（イギリス・イーストアングリア大学の氷海水槽など）での室内実験も実施。専門は、海氷生物地球化学。
Researchmap個人ページ
ホームページURL
研究者番号
- 70550739
J-Global ID
■経歴
経歴
- 2025年04月 - 現在
北海道大学, 大学院水産科学研究院, 教授 - 2024年01月 - 現在
SOLAS SSC member - 2023年12月 - 現在
BEPSII SSC member - 2021年09月 - 現在
SCOR WG163 Full member - 2021年04月 - 現在
国立極地研究所, 客員准教授 - 2018年01月 - 現在
CATCH SSC member - 2016年04月 - 現在
北海道大学北極域研究センター, 兼任 - 2020年04月 - 2025年03月
北海道大学, 北方生物圏フィールド科学センター, 准教授, 日本国 - 2016年06月 - 2023年12月
SCOR WG152 Co-chair - 2015年10月 - 2020年03月
北海道大学大学院水産科学研究院 助教, Faculty of Fisheries Sciences - 2015年04月 - 2015年09月
北海道大学低温科学研究所 非常勤研究員, Institute of Low Temperature Science - 2013年04月 - 2015年03月
日本学術振興会 特別研究員PD（北海道大学低温科学研究所） - 2012年04月 - 2013年03月
日本学術振興会 特別研究員PD（ノルウェー極地研究所） - 2011年04月 - 2012年03月
日本学術振興会 海外特別研究員（ノルウェー極地研究所） - 2009年04月 - 2011年03月
国立極地研究所 特任研究員 - 2008年04月 - 2009年03月
日本学術振興会 特別研究員PD（北海道大学低温科学研究所） （DC2採用後PDに変更） - 2007年04月 - 2008年03月
日本学術振興会 特別研究員DC2（北海道大学大学院環境科学院）
■研究活動情報
論文
- Algal enrichment process for newly formed sea ice in the Dalton polynya off East Antarctica during the late summer–early autumn
Keigo D. Takahashi, Masato Ito, Natsumi Nojiro, Daiki Nomura, Masayoshi Sano, Shigeru Aoki, Pat Wongpan, Guy D. Williams, Michiyo Yamamoto-Kawai, Takeshi Tamura, Masato Moteki, Toru Hirawake, Ryosuke Makabe
Elem Sci Anth, 13, 1, University of California Press, 2025年06月02日, ［査読有り］
研究論文（学術雑誌）, Newly formed sea ice can incorporate considerable amounts of organic matter including phytoplankton during its freezing and growth. This initial incorporation influences the standing stocks of ice algae, a fundamental component of high-latitude marine ecosystems. Physical incorporation via the accretion of frazil ice, instead of congelation growth, is considered to incorporate particles efficiently. However, for thin ice (<0.20 m thickness), information on the relationship between ice texture and particle incorporation is scarce. Here, we assessed sea-ice texture (proportion of frazil ice-origin layer), macronutrient concentrations, fraction of snow, and algal composition in Antarctic sea ice and their effects on the enrichment of algae into thin ice in terms of chlorophyll a (Chl a) and biogenic silica (BSi). Chl a and BSi concentrations of thin ice ranged over 0.2–11.6 µg L−1 and 0.5–11.1 µmol L−1, respectively, being significantly concentrated compared to seawater. BSi enrichment in thin ice correlated negatively with the proportion of frazil ice-origin layer, while no relationship was observed with Chl a enrichment. These results suggest that frazil ice could play a minor role in entraining algal cells under certain circumstances, possibly due to the low turbulence and wind speeds of the late summer–early autumn season dampening the interaction between frazil ice and phytoplankton. Algal composition data could suggest that ice algae from the previous winter’s sea ice were released and re-incorporated into the surrounding thin ice on its formation, given the high similarity in species composition observed between older ice and several thin ice samples. This mechanism potentially promotes algal enrichment without the accretion of frazil ice, as indicated by the maximum enrichment in thin ice which developed via congelation growth. Our results show that algal concentration in thin ice could be affected by the presence of old sea ice and hydrographic and meteorological conditions. - Observation‐Based Estimate of Net Community Production in Antarctic Sea Ice
Laura A. Dalman, Klaus M. Meiners, David N. Thomas, Florian Deman, Sophie Bestley, Sébastien Moreau, Kevin R. Arrigo, Karley Campbell, Matthew Corkill, Stefano Cozzi, Bruno Delille, Agneta Fransson, Alexander D. Fraser, Sian F. Henley, Julie Janssens, Delphine Lannuzel, David R. Munro, Daiki Nomura, Louisa Norman, Stathys Papadimitriou, Christina Schallenberg, Jean‐Louis Tison, Martin Vancoppenolle, Pier van der Merwe, François Fripia
Geophysical Research Letters, 52, 7, American Geophysical Union (AGU), 2025年04月16日, ［査読有り］
英語, 研究論文（学術雑誌）, Abstract
Antarctic sea ice is one of the largest biomes on Earth providing a critical habitat for ice algae. Measurements of primary production in Antarctic sea ice remain scarce and an observation‐based estimate of primary production has not been revisited in over 30 years. We fill this knowledge gap by presenting a newly compiled circumpolar data set of particulate and dissolved organic carbon from 362 ice cores, sampled between 1989 and 2019, to estimate sea‐ice net community production using a carbon biomass accumulation approach. Our estimate of 26.8–32.9 Tg C yr−1 accounts for at least 15%–18% of the total primary production in the Antarctic sea‐ice zone, less than a previous observation‐based estimate (63–70 Tg C yr−1) and consistent with recent modeled estimates. The results underpin the ecological significance of sea‐ice algae as an early season resource for pelagic food webs. - Dynamic ice–ocean pathways along the Transpolar Drift amplify the dispersal of Siberian matter
Georgi Lauker, Dorothea Bauch, Benjamin Rabe, Thomas Krumpen, Ellen Damm, Markus Kienas, Ed Hathorne, Myriel Vredenborg, Sandra Tippenhauer, Nils Andersen, Hanno Meyer, Moein Mella, Alessandra D’Angelo, Patric Simões Pereira, Daiki Nomura, Tristan J. Horner, Katharine Hendry, Stephanie S. Kienas
Nature Communications, 16, 1, Springer Science and Business Media LLC, 2025年04月14日, ［査読有り］
研究論文（学術雑誌）, Abstract
The Transpolar Drift (TPD) plays a crucial role in regulating Arctic climate and ecosystems by transporting fresh water and key substances, such as terrestrial nutrients and pollutants, from the Siberian Shelf across the Arctic Ocean to the North Atlantic. However, year-round observations of the TPD remain scarce, creating significant knowledge gaps regarding the influence of sea ice drift and ocean surface circulation on the transport pathways of Siberian fresh water and associated matter. Using geochemical provenance tracer data collected over a complete seasonal cycle, our study reveals substantial spatiotemporal variability in the dispersal pathways of Siberian matter along the TPD. This variability reflects dynamic shifts in contributions of individual Siberian rivers as they integrate into a large-scale current system, followed by their rapid and extensive redistribution through a combination of seasonal ice–ocean exchanges and divergent ice drift. These findings emphasize the complexity of Arctic ice–ocean transport pathways and highlight the challenges of forecasting their dynamics in light of anticipated changes in sea ice extent, river discharge, and surface circulation patterns. - A novel probe to sample dissolved and particulate matter in sea ice at high vertical resolution
Matthew Corkill, Takenobu Toyota, Daiki Nomura, Klaus M. Meiners, Pat Wongpan, Ryota Akino, Nana Samori, Masaki Yoshimura, Ashley T. Townsend, Trevor Corkill, Delphine Lannuzel
Elem Sci Anth, 13, 1, University of California Press, 2025年04月08日, ［査読有り］
研究論文（学術雑誌）, Sea ice can be interspersed vertically with both permeable and impermeable layers. These features can be smaller than a few centimetres but are important for understanding biogeochemical cycles in sea ice. Traditionally, sea-ice samples are collected by drilling into the ice with a rotating core barrel with a cutting head. Ice cores are extracted and then cut into sections that are melted to collect the variable of interest. Drawbacks to this method include difficulty cutting sections smaller than a few centimetres thick and contamination of samples. Brines may also drain from their in-situ locations and be lost, meaning that important micro-environments in sea ice may be overlooked or misrepresented. To address these drawbacks, we developed a sea-ice melt probe that bores into sea ice and collects high-resolution samples. The capability of the melt probe to delineate a layer of dye in artificial sea ice was tested during cold laboratory-based experiments. Complementary field experiments were carried out in first-year landfast sea ice during February–March 2023 at Saroma-ko Lagoon, Japan. Experiments consisted of testing the high-vertical-resolution capability of the melt probe as well as its ability to be deployed on snow-covered sea ice. The melt probe was able to delineate a layer of dye at a finer resolution (20 mm) than traditional ice coring (approximately 50–100 mm) and could sample sea-ice brine in the field at a high vertical resolution. Melt-probe samples were also used to measure iron in sea ice without contamination. This proof-of-concept study provides an alternative method of sampling sea ice with the ability to support new research on fine-scale structures, with applications for sampling dissolved and particulate sea-ice constituents including trace metals, macro-nutrients, microplastics and gases. - Arctic marine environments regulated by ocean transport and air‒sea‒land interaction: Findings from the ArCS II Ocean Research Program
Eiji Watanabe, Hiromichi Ueno, Tsubasa Kodaira, Akihiko Murata, Shigeto Nishino, Takahito Ikenoue, Masanobu Yamamoto, Daiki Nomura, Hiroto Abe, Yusuke Kawaguchi, Daisuke Hirano, Yuanxin Zhang, Sayaka Yasunaka
Polar Science, 101205, 101205, Elsevier BV, 2025年04月, ［査読有り］
研究論文（学術雑誌） - Overwintering Fish Community in Ice‐Covered Environments in Hokkaido, Japan, Inferred From Environmental
DNA
Tatsuya Kawakami, Makoto Ozaki, Aya Yamazaki, Daiki Nomura, Akihide Kasai
Environmental DNA, 7, 2, Wiley, 2025年03月04日, ［査読有り］
英語, 研究論文（学術雑誌）, ABSTRACT
The overwintering ecology of fish in the seasonal ice zones (SIZs) remains largely unexplored owing to methodological limitations. Environmental DNA (eDNA) can reveal the distribution and diversity of fish species in various aquatic environments, thereby offering a possible solution to the methodological limitations of SIZ studies. Therefore, we aimed to detect the overwintering fish community in the ice‐covered Saroma‐ko Lagoon, located on the Okhotsk Sea coast of Hokkaido, and its inflow, using eDNA metabarcoding. eDNA extracted from under‐ice seawater collected from the lagoon yielded 28 fish taxa, predominantly Clupea pallasii based on the relative DNA read abundance. Dissimilarity analysis suggested short‐term temporal variations in eDNA composition in under‐ice seawater, even at the same site. Nineteen fish taxa, predominantly Tribolodon brandtii and T. hakonensis, were detected in the eDNA extracted from under‐ice river water. The high dissimilarity between eDNA results from under‐ice seawater and river water suggested segregation of the overwintering community between the lagoon and river. Fish eDNA detected in meltwater from sea ice was assigned to five taxa, suggesting the entrainment of particulate matter containing fish eDNA during ice growth. The true species richness estimated based on eDNA results and discrepancies with historical reports suggest that sampling efforts need to be optimized for ice‐covered environments to promote more comprehensive species detection. This study demonstrated the usefulness of using fish eDNA metabarcoding to study the ecology of overwintering fish under ice. Clarifying eDNA shedding patterns, persistence, and dispersal in under‐ice environments would improve the reliability of this technique and expand its use in SIZs. - Spatial distributions of iron and manganese in surface waters of the Arctic's Laptev and East Siberian seas
Naoya Kanna, Kazutaka Tateyama, Takuji Waseda, Anna Timofeeva, Maria Papadimitraki, Laura Whitmore, Hajime Obata, Daiki Nomura, Hiroshi Ogawa, Youhei Yamashita, Igor Polyakov
Biogeosciences, 22, 4, 1057, 1076, Copernicus GmbH, 2025年02月26日, ［査読有り］
研究論文（学術雑誌）, Abstract. The Arctic Laptev and East Siberian seas (LESS) have high biogeochemical activity. Nutrient inputs associated with river runoff and shelf sediment–water exchange processes are vital for supporting primary production in the LESS. Relative to macronutrients, data on dissolved iron (dFe) and manganese (dMn), which are essential micronutrients for primary producers, have historically been sparse for LESS. Some dFe and dMn are reportedly carried in the central Arctic by the Transpolar Drift, a major current that directly transports Eurasian shelf water, river water, and sea ice from the LESS continental margins. However, the supply of dFe and dMn to the surface waters of the LESS and the subsequent biogeochemical processes are not well constrained. In the summer of 2021, we investigated the following questions: what are the sources of dFe and dMn in the surface layer and which factors control their concentrations and distributions on the LESS continental margins? We demonstrated strong regional controls on dFe and dMn distributions based on distinct hydrographic regimes between the eastern side of the LESS (East Siberian Sea and Chukchi Abyssal Plain) and the western side (Makarov and Amundsen basins). Specifically, the East Siberian Sea and Chukchi Abyssal Plain were governed by Pacific-sourced water, and the Makarov and Amundsen basins were influenced by Atlantic-sourced water. Pacific-sourced water contained higher levels of dMn released from continental shelf sediments than Atlantic-sourced water. In contrast, elevated dFe signals were not observed, likely because sedimentary dFe was more rapidly removed from the water column through oxidation or scavenging than dMn was. The impact of river water discharge on the dFe distributions of Pacific- and Atlantic-sourced water was significant. A positive correlation between the fraction of meteoric water (river water and precipitation), dFe, and humic-like colored dissolved organic matter (CDOM) in these waters confirmed that dFe and CDOM are common freshwater sources. Terrigenous organic ligands likely stabilize Fe in the dissolved phase, which is not the case for Mn. Sea ice melting and formation were not significant sources during the observation period. We conclude that the major sources controlling the dFe and dMn distributions on the LESS continental margins are river discharge and shelf sediment input. - Melt pond CO2 dynamics and fluxes with the atmosphere in the central Arctic Ocean during the summer-to-autumn transition
Masaki Yoshimura, Daiki Nomura, Alison L. Webb, Yuhong Li, Manuel Dall’osto, Katrin Schmid, Elise S. Droste, Emelia J. Chamberlain, Kevin M. Posman, Hélène Ango, Byron Blomquis, Hanno Meyer, Mario Hoppema, Manami Tozawa, Jun Inoue, Bruno Delille
Elem Sci Anth, 13, 1, University of California Press, 2025年01月20日, ［査読有り］
研究論文（学術雑誌）, Melt ponds are a common feature of the Arctic sea-ice environment during summer, and they play an important role in the exchange of heat and water vapor between the ocean and the atmosphere. We report the results of a time-series study of the CO2 dynamics within melt ponds (and nearby lead) and related fluxes with the atmosphere during the summer-to-autumn transition in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. In late summer 2020, low-salinity meltwater was distributed throughout the melt ponds, and undersaturation of pCO2 in the meltwater drove a net influx of CO2 from the atmosphere. The meltwater layer subsequently thinned due to seawater influx, and a strong gradient in salinity and low-pCO2 water was observed at the interface between meltwater and seawater at the beginning of September. Mixing between meltwater and underlying seawater drives a significant drawdown of pCO2 as a result of the non-linearities in carbonate chemistry. By the middle of September, the strong stratification within the meltwater had dissipated. Subsequent freezing then began, and cooling and wind-induced drifting of ice floes caused mixing and an influx of seawater through the bottom of the melt pond. The pCO2 in the melt pond reached 300 µatm as a result of exchanging melt pond water with the underlying seawater. However, gas exchange was impeded by the formation of impermeable freshwater ice on the surface of the melt pond, and the net flux of CO2 was nearly zero into the pond, which was no longer a sink for atmospheric CO2. Overall, the melt ponds in this Arctic sea-ice area (both melt ponds and lead water) act as moderate sinks for atmospheric CO2. - 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, 2025年01月, ［査読有り］
英語, 研究論文（学術雑誌） - Different vertical distribution of diatoms in sea ice at the river mouth and off the eastern coast of Saroma-ko Lagoon, Hokkaido, Japan
Keigo D. Takahashi, Daiki Nomura, Yuichi Nosaka
Laguna, 31, 15, 24, Japanese Association for Estuarine Science, 2024年12月31日, ［査読有り］
英語, 研究論文（学術雑誌） - An analysis of air-sea gas exchange for the entire MOSAiC Arctic drift
Brice Loose, Ilker Fer, Adam Ulfsbo, Melissa Chierici, Elise S. Droste, Daiki Nomura, Agneta Fransson, Mario Hoppema, Sinhué Torres-Valdés
Elem Sci Anth, 12, 1, University of California Press, 2024年10月08日, ［査読有り］
英語, 研究論文（学術雑誌）, Sea ice cover influences the generation of surface ocean turbulence in ways that sometimes enhance, but mostly inhibit air-water gas exchange. Inhibition happens as ice cover reduces wind fetch, enhancement occurs when haline convection or sea ice drift creates additional surface turbulence. We used the bulk turbulence relationships within the Wave Age Gas Transfer model to estimate air-sea gas transfer velocity (kWAGT), based on sea ice cover and turbulence conditions in the ice-ocean boundary layer, throughout a year-long (2019–2020) ice drift campaign in the central Arctic Ocean. During the drift, sea ice cover averaged >97%, with a minimum of 58%, and boundary layer shear played a dominant role in the turbulence budget. Modeled turbulent kinetic energy dissipation was compared against 167 in-situ profiles of ocean dissipation to evaluate model performance and explore related processes. The modeled dissipation and observed dissipation profiles, averaged over 0–4 m depth, agreed within 1% of each other, with a mean dissipation of 5.8 × 10−7 W kg−1. Examining individual dissipation estimates by surface conditions, however, revealed poorest agreement in leads, especially leads covered by thin ice, which the model cannot detect. Dissipation from the model was used to produce a time series of kWAGT, revealing an average velocity of 0.034 m d−1 or 1% of the global average for the open ocean. Comparison with a widely used wind speed parameterization for gas exchange showed that wind speed scaling would overestimate k during 92% of the drift by 3.5 times on average, demonstrating how fetch limitation can suppress gas exchange, even as open water increases. These results suggest that photic zone processes, under-ice blooms, and attendant cycling of CO2 and O2 as well as CH4 can remain isolated from the atmosphere for an entire annual cycle in the central Arctic. - Overview of the MOSAiC expedition: Ecosystem
Allison A. Fong, Clara J. M. Hoppe, Nicole Aberle, Carin J. Ashjian, Philipp Assmy, Youcheng Bai, Dorothee C. E. Bakker, John P. Balmonte, Kevin R. Barry, Stefan Bertilsson, William Boulton, Jeff Bowman, Deborah Bozzato, Gunnar Bratbak, Moritz Buck, Robert G. Campbell, Giulia Castellani, Emelia J. Chamberlain, Jianfang Chen, Melissa Chierici, Astrid Cornils, Jessie M. Creamean, Ellen Damm, Klaus Dethloff, Elise S. Droste, Oliver Ebenhöh, Sarah L. Eggers, Anja Engel, Hauke Flores, Agneta Fransson, Stephan Frickenhaus, Jessie Gardner, Cecilia E. Gelfman, Mats A. Granskog, Martin Graeve, Charlotte Havermans, Céline Heuzé, Nicole Hildebrand, Thomas C. J. Hill, Mario Hoppema, Antonia Immerz, Haiyan Jin, Boris P. Koch, Xianyu Kong, Alexandra Kraberg, Musheng Lan, Benjamin A. Lange, Aud Larsen, Benoit Lebreton, Eva Leu, Brice Loose, Wieslaw Maslowski, Camille Mavis, Katja Metfies, Thomas Mock, Oliver Müller, Marcel Nicolaus, Barbara Niehoff, Daiki Nomura, Eva-Maria Nöthig, Marc Oggier, Ellen Oldenburg, Lasse Mork Olsen, Ilka Peeken, Donald K. Perovich, Ovidiu Popa, Benjamin Rabe, Jian Ren, Markus Rex, Annette Rinke, Sebastian Rokitta, Björn Ros, Serdar Sakinan, Evgenii Salganik, Fokje L. Schaafsma, Hendrik Schäfer, Katrin Schmid, Katyanne M. Shoemaker, Matthew D. Shupe, Pauline Snoeijs-Leijonmalm, Jacqueline Stefels, Anders Svenson, Ran Tao, Sinhué Torres-Valdés, Anders Torstensson, Andrew Toseland, Adam Ulfsbo, Maria A. Van Leeuwe, Martina Vortkamp, Alison L. Webb, Yanpei Zhuang, Rolf R. Gradinger
Elem Sci Anth, 12, 1, University of California Press, 2024年08月21日, ［査読有り］
研究論文（学術雑誌）, The international and interdisciplinary sea-ice drift expedition “The Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC) was conducted from October 2019 to September 2020. The aim of MOSAiC was to study the interconnected physical, chemical, and biological characteristics and processes from the atmosphere to the deep sea of the central Arctic system. The ecosystem team addressed current knowledge gaps and explored unknown biological properties over a complete seasonal cycle focusing on three major research areas: biodiversity, biogeochemical cycles, and linkages to the environment. In addition to the measurements of core properties along a complete seasonal cycle, dedicated projects covered specific processes and habitats, or organisms on higher taxonomic or temporal resolution in specific time windows. A wide range of sampling instruments and approaches, including sea-ice coring, lead sampling with pumps, rosette-based water sampling, plankton nets, remotely operated vehicles, and acoustic buoys, was applied to address the science objectives. Further, a broad range of process-related measurements to address, for example, productivity patterns, seasonal migrations, and diversity shifts, were made both in situ and onboard RV Polarstern. This article provides a detailed overview of the sampling approaches used to address the three main science objectives. It highlights the core sampling program and provides examples of habitat- or process-specific sampling. The initial results presented include high biological activities in wintertime and the discovery of biological hotspots in underexplored habitats. The unique interconnectivity of the coordinated sampling efforts also revealed insights into cross-disciplinary interactions like the impact of biota on Arctic cloud formation. This overview further presents both lessons learned from conducting such a demanding field campaign and an outlook on spin-off projects to be conducted over the next years. - Impact of anticyclonic eddy on fish distribution in the Kuroshio-Oyashio transition area
Ryo Dobashi, Hiromichi Ueno, Riku Kato, Naizheng Yan, Tohru Mukai, Hiroki Yasuma, Daiki Nomura, Sachihiko Itoh, Akihide Kasai
Bulletin of the Japanese Society of Fisheries Oceanography, 88, 3, 178, 189, 2024年08月, ［査読有り］ - Spatial distributions of iron and manganese in surface waters in the Arctic’s Laptev and East Siberian seas
Naoya Kanna, Kazutaka Tateyama, Takuji Waseda, Anna Timofeeva, Maria Papadimitraki, Laura Whitmore, Hajime Obata, Daiki Nomura, Hiroshi Ogawa, Youhei Yamashita, Igor Polyakov
Copernicus GmbH, 2024年07月11日, ［査読有り］
Abstract. The Arctic’s Laptev and East Siberian Seas (LESS) is a region with high biogeochemical activity. Nutrient inputs associated with river runoff and shelf sediment-water exchange processes are vital for supporting primary production in the LESS. However, the dynamics of trace metals such as iron (Fe) and manganese (Mn), which are essential micronutrients for primary producers, remain unknown in the LESS. Here, we present data on Fe and Mn in surface waters in the late summer of 2021 and discuss the factors controlling their concentrations and distributions on the surface of the LESS continental margins. Property of surface waters in the East Siberian Sea and Chukchi Abyssal Plain differed significantly from the Makarov and Amundsen Basins. Nutrient-rich Pacific-sourced water exists in the East Siberian Shelf with a high dissolved Mn (dMn) concentration. Pacific-sourced water also receives a large sedimentary flux that releases dMn onto the continental shelf. Dissolved Fe (dFe) could have been released on the shelf as well; however, dFe remained low in the Pacific-sourced water. This is because dFe re-precipitated more rapidly than dMn because of the difference in removal kinetics. In contrast, relatively nutrient-poor Atlantic-sourced water exists in the Makarov and Amundsen Basins. A positive correlation between the fraction of meteoric water (river water and precipitation), dFe, and humic-like colored dissolved organic matter (CDOM) in Atlantic-sourced water confirmed a common freshwater source for dFe and CDOM. Terrigenous organic ligands likely stabilized Fe in the dissolved phase, which was not the case for Mn. The fraction of sea ice meltwater was not correlated with dFe and dMn in any part of the sampling domain. Our results indicate that the major factors controlling these metal concentrations in the LESS continental margins are river discharge and the input of shelf sediment. - Quantitative Assessment of Factors Contributing to Variations in Sea Surface pCO2 in the Pacific Sector of the Arctic Ocean
Manami Tozawa, Daiki Nomura, Mirai Matsuura, Mariko Hatta, Amane Fujiwara, Sayaka Yasunaka, Akihiko Murata
Journal of Geophysical Research: Oceans, 129, 6, American Geophysical Union (AGU), 2024年06月06日, ［査読有り］
研究論文（学術雑誌）, Abstract
To quantitatively assess seasonal variations in the partial pressure of carbon dioxide (pCO2) in the Pacific sector of the Arctic Ocean (Canada Basin and Chukchi Sea) in 2021, water temperature, salinity, chlorophyll‐a, pCO2, dissolved inorganic carbon (DIC), total alkalinity (TA), and nutrients were measured. During summer 2021, surface water pCO2 in our study area (315 ± 41 μatm) was undersaturated with respect to the atmosphere (404 ± 4 μatm), and the ocean was a sink for atmospheric CO2 (−10.5 ± 11.0 mmol C m−2 day−1). Using DIC, TA, and nutrients in the temperature minimum layer, we estimated the under‐ice pCO2 in the water during the previous winter and calculated changes in pCO2 (δpCO2) due to temperature changes, freshwater inflow, biological activity, and other factors (gas exchange and advection) from winter to summer. In the Chukchi Sea, biological activity and temperature changes had significant impacts on pCO2, whereas in the Canada Basin, the influx of freshwater caused a significant decrease in pCO2. Our results suggested that different types of freshwaters had different effects on pCO2, with sea ice meltwater having a greater effect on reducing pCO2 than river water or snowmelt water. We therefore emphasize the importance of freshwater type and proportion, as well as freshwater supply, for prediction of future pCO2 changes. - Multidisciplinary research for sea ice in Saroma-ko Lagoon, Hokkaido, Japan 2023
Daiki NOMURA, Ryota AKINO, Matthew CORKILL, Keizo HIRANO, Akihide KASAI, Seiji KATAKURA, Yusuke KAWAGUCHI, Tatsuya KAWAKAMI, Riri KIMURA, Delphine LANNUZEL, Ryosuke MAKABE, Mirai MATSUURA, Kohei MATSUNO, Klaus MEINERS, Keizo NAGASAKI, Yuichi NOSAKA, Nana SAMORI, Shinnosuke SAKAYA, Eun Yae SON, Ryotaro SUGA, Yumi SUNAKAWA, Keigo D. TAKAHASHI, Masaharu TAKAHASHI, Yuka TAKEDA, Takenobu TOYOTA, Manami TOZAWA, Pat WONGPAN, Hiroshi YOSHIDA, Kazuhiro YOSHIDA, Masaki YOSHIMURA
Bulletin of Glaciological Research, 42, 19, 37, Japanese Society of Snow and Ice, 2024年06月, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌） - Characteristics of late summer Arctic brash sea ice and its melting effect on the surface-water biogeochemistry of the Chukchi Shelf and Canada Basin
Ryota Akino, Daiki Nomura, Reishi Sahashi, Manami Tozawa, Mariko Hatta, Kohei Matsuno, Wakana Endo, Takuhei Shiozaki, Tatsuya Kawakami, Masato Ito, Akihiko Murata, Amane Fujiwara
Elem Sci Anth, 12, 1, University of California Press, 2024年05月27日, ［査読有り］
研究論文（学術雑誌）, To understand the impact of the melting of late summer Arctic brash ice on the surface waters of the Chukchi Sea, we collected sea-ice samples during 2021. Floating sea ice was collected by a wire mesh pallet cage from the side of the R/V Mirai. We measured physical and biogeochemical parameters such as salinity, oxygen stable isotopic ratios, turbidity, and concentrations of chlorophyll-a and nutrients. The samples of brash ice were multiyear ice based on satellite back-trajectory analysis. Comparison of nutrient concentrations in brash ice with those of seawater samples from the temperature minimum layer similar to the water in the sea ice originated suggested that the characteristics of the brash ice were greatly affected by biogeochemical processes such as remineralization. The extremely high turbidity and concentrations of chlorophyll-a observed in the brown/green ice samples reflected the impact of sediment as well as the influence of biological activities. The N:P ratios were less than 1 because of the high phosphate concentrations, even though the ammonium concentrations were high. We hypothesized that this low N:P ratio reflected the combined effects of the accumulation of nutrients due to remineralization in the biofilm and differences of remineralization rate and adsorption features of nitrogen and phosphorus. Based on the high nitrate and ammonium concentrations in the sea-ice samples, we postulated a marked impact of sea-ice meltwater on the nitrogen cycle in the nitrate-depleted surface waters of the Chukchi Sea during late summer. We estimated that meltwater nitrogen could support 0.3%–2.6% of primary production in the northern Chukchi Sea. Our results suggest that high-turbidity ice will play an important role as a source of nutrients to the ocean during melting of sea ice, and understanding its distribution, amount, and geochemical characteristics is vital. - Revisiting circulation and water masses over the East Antarctic margin (80–150°E)
Kaihe Yamazaki, Katsuro Katsumata, Daisuke Hirano, Daiki Nomura, Hiroko Sasaki, Hiroto Murase, Shigeru Aoki
Progress in Oceanography, 103285, 103285, Elsevier BV, 2024年05月, ［査読有り］
研究論文（学術雑誌） - Classification of optical water groups in the subarctic Pacific and adjacent seas using satellite-derived light absorption spectra of chromophoric dissolved organic matter
Joji Oida, Toru Hirawake, Youhei Yamashita, Hiroto Abe, Jun Nishioka, Hisatomo Waga, Daiki Nomura, Shigeho Kakehi
Deep Sea Research Part I: Oceanographic Research Papers, 104313, 104313, Elsevier BV, 2024年04月, ［査読有り］
研究論文（学術雑誌） - Oceanographic factors determining the distribution of nutrients and primary production in the subpolar Southern Ocean
Manami Tozawa, Daiki Nomura, Kaihe Yamazaki, Masaaki Kiuchi, Daisuke Hirano, Shigeru Aoki, Hiroko Sasaki, Hiroto Murase
Progress in Oceanography, 103266, 103266, Elsevier BV, 2024年04月, ［査読有り］
研究論文（学術雑誌） - Isotopic signatures of snow, sea ice, and surface seawater in the central Arctic Ocean during the MOSAiC expedition
Moein Mella, Camilla F. Brunello, Martin Werner, Dorothea Bauch, Ellen Damm, Michael Angelopoulos, Daiki Nomura, Jeffrey M. Welker, Martin Schneebeli, Mats A. Granskog, Maria Hoerhold, Amy R. Macfarlane, Stefanie Arnd, Hanno Meyer
Elem Sci Anth, 12, 1, University of California Press, 2024年02月22日, ［査読有り］
英語, 研究論文（学術雑誌）, The Arctic Ocean is an exceptional environment where hydrosphere, cryosphere, and atmosphere are closely interconnected. Changes in sea-ice extent and thickness affect ocean currents, as well as moisture and heat exchange with the atmosphere. Energy and water fluxes impact the formation and melting of sea ice and snow cover. Here, we present a comprehensive statistical analysis of the stable water isotopes of various hydrological components in the central Arctic obtained during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2019–2020, including the understudied Arctic winter. Our dataset comprises >2200 water, snow, and ice samples. Snow had the most depleted and variable isotopic composition, with δ18O (–16.3‰) increasing consistently from surface (–22.5‰) to bottom (–9.7‰) of the snowpack, suggesting that snow metamorphism and wind-induced transport may overprint the original precipitation isotope values. In the Arctic Ocean, isotopes also help to distinguish between different sea-ice types, and whether there is a meteoric contribution. The isotopic composition and salinity of surface seawater indicated relative contributions from different freshwater sources: lower δ18O (approximately –3.0‰) and salinities were observed near the eastern Siberian shelves and towards the center of the Transpolar Drift due to river discharge. Higher δ18O (approximately –1.5‰) and salinities were associated with an Atlantic source when the RV Polarstern crossed the Gakkel Ridge into the Nansen Basin. These changes were driven mainly by the shifts within the Transpolar Drift that carried the Polarstern across the Arctic Ocean. Our isotopic analysis highlights the importance of investigating isotope fractionation effects, for example, during sea-ice formation and melting. A systematic full-year sampling for water isotopes from different components strengthens our understanding of the Arctic water cycle and provides crucial insights into the interaction between atmosphere, sea ice, and ocean and their spatio-temporal variations during MOSAiC. - Comparisons of different sample air-drying systems for carbon dioxide flux measurements based on eddy covariance in cold environments
Taichi NOSHIRO, Daiki NOMURA, Fumiyoshi KONDO, Keisuke ONO, Brent ELSE, Hiroki IKAWA
Journal of Agricultural Meteorology, 80, 1, 22, 28, Society of Agricultural Meteorology of Japan, 2024年01月10日, ［査読有り］
英語, 研究論文（学術雑誌） - Size-fractionated phytoplankton biomass and primary production in the eastern Indian sector of the Southern Ocean in the austral summer 2018/2019
Akihiro Shiomoto, Hiroko Sasaki, Daiki Nomura
Progress in Oceanography, 218, 103119, 103119, Elsevier BV, 2023年11月, ［査読有り］, ［最終著者］
研究論文（学術雑誌） - Responses of diatom assemblages and life cycle to sea ice variation in the eastern Indian sector of the Southern Ocean during austral summer 2018/2019
Kohei Matsuno, Kohei Sumiya, Manami Tozawa, Daiki Nomura, Hiroko Sasaki, Atsushi Yamaguchi, Hiroto Murase
Progress in Oceanography, 218, 103117, 103117, Elsevier BV, 2023年11月, ［査読有り］
研究論文（学術雑誌） - Polar oceans and sea ice in a changing climate
Megan D. Willis, Delphine Lannuzel, Brent Else, Hélène Ango, Karley Campbell, Odile Crabeck, Bruno Delille, Hakase Hayashida, Martine Lizotte, Brice Loose, Klaus M. Meiners, Lisa Miller, Sebastien Moreau, Daiki Nomura, John Prytherch, Julia Schmale, Nadja Steiner, Letizia Tedesco, Jennie Thomas
Elem Sci Anth, 11, 1, University of California Press, 2023年10月18日, ［査読有り］
英語, 研究論文（学術雑誌）, Polar oceans and sea ice cover 15% of the Earth’s ocean surface, and the environment is changing rapidly at both poles. Improving knowledge on the interactions between the atmospheric and oceanic realms in the polar regions, a Surface Ocean–Lower Atmosphere Study (SOLAS) project key focus, is essential to understanding the Earth system in the context of climate change. However, our ability to monitor the pace and magnitude of changes in the polar regions and evaluate their impacts for the rest of the globe is limited by both remoteness and sea-ice coverage. Sea ice not only supports biological activity and mediates gas and aerosol exchange but can also hinder some in-situ and remote sensing observations. While satellite remote sensing provides the baseline climate record for sea-ice properties and extent, these techniques cannot provide key variables within and below sea ice. Recent robotics, modeling, and in-situ measurement advances have opened new possibilities for understanding the ocean–sea ice–atmosphere system, but critical knowledge gaps remain. Seasonal and long-term observations are clearly lacking across all variables and phases. Observational and modeling efforts across the sea-ice, ocean, and atmospheric domains must be better linked to achieve a system-level understanding of polar ocean and sea-ice environments. As polar oceans are warming and sea ice is becoming thinner and more ephemeral than before, dramatic changes over a suite of physicochemical and biogeochemical processes are expected, if not already underway. These changes in sea-ice and ocean conditions will affect atmospheric processes by modifying the production of aerosols, aerosol precursors, reactive halogens and oxidants, and the exchange of greenhouse gases. Quantifying which processes will be enhanced or reduced by climate change calls for tailored monitoring programs for high-latitude ocean environments. Open questions in this coupled system will be best resolved by leveraging ongoing international and multidisciplinary programs, such as efforts led by SOLAS, to link research across the ocean–sea ice–atmosphere interface. - Macronutrient biogeochemistry in Antarctic land-fast sea ice: Insights from a circumpolar data compilation
Sian F. Henley, Stefano Cozzi, François Fripia, Delphine Lannuzel, Daiki Nomura, David N. Thomas, Klaus M. Meiners, Martin Vancoppenolle, Kevin Arrigo, Jacqueline Stefels, Maria van Leeuwe, Sebastien Moreau, Elizabeth M. Jones, Agneta Fransson, Melissa Chierici, Bruno Delille
Marine Chemistry, 104324, 104324, Elsevier BV, 2023年10月, ［査読有り］
研究論文（学術雑誌） - Thin and transient meltwater layers and false bottoms in the Arctic sea ice pack—Recent insights on these historically overlooked features
Madison M. Smith, Hélène Ango, Emelia J. Chamberlain, Elise S. Droste, Salar Karam, Morven Muilwijk, Alison L. Webb, Stephen D. Archer, Ivo Beck, Byron W. Blomquis, Jeff Bowman, Matthew Boyer, Deborah Bozzato, Melissa Chierici, Jessie Creamean, Alessandra D’Angelo, Bruno Delille, Ilker Fer, Allison A. Fong, Agneta Fransson, Niels Fuchs, Jessie Gardner, Mats A. Granskog, Clara J. M. Hoppe, Mario Hoppema, Mario Hoppmann, Thomas Mock, Sofia Muller, Oliver Müller, Marcel Nicolaus, Daiki Nomura, Tuukka Petäjä, Evgenii Salganik, Julia Schmale, Katrin Schmid, Kirstin M. Schulz, Matthew D. Shupe, Jacqueline Stefels, Linda Thielke, Sandra Tippenhauer, Adam Ulfsbo, Maria van Leeuwe, Melinda Webster, Masaki Yoshimura, Liyang Zhan
Elem Sci Anth, 11, 1, University of California Press, 2023年09月07日, ［査読有り］
研究論文（学術雑誌）, The rapid melt of snow and sea ice during the Arctic summer provides a significant source of low-salinity meltwater to the surface ocean on the local scale. The accumulation of this meltwater on, under, and around sea ice floes can result in relatively thin meltwater layers in the upper ocean. Due to the small-scale nature of these upper-ocean features, typically on the order of 1 m thick or less, they are rarely detected by standard methods, but are nevertheless pervasive and critically important in Arctic summer. Observations during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in summer 2020 focused on the evolution of such layers and made significant advancements in understanding their role in the coupled Arctic system. Here we provide a review of thin meltwater layers in the Arctic, with emphasis on the new findings from MOSAiC. Both prior and recent observational datasets indicate an intermittent yet long-lasting (weeks to months) meltwater layer in the upper ocean on the order of 0.1 m to 1.0 m in thickness, with a large spatial range. The presence of meltwater layers impacts the physical system by reducing bottom ice melt and allowing new ice formation via false bottom growth. Collectively, the meltwater layer and false bottoms reduce atmosphere-ocean exchanges of momentum, energy, and material. The impacts on the coupled Arctic system are far-reaching, including acting as a barrier for nutrient and gas exchange and impacting ecosystem diversity and productivity. - Impacts of Basal Melting of the Totten Ice Shelf and Biological Productivity on Marine Biogeochemical Components in Sabrina Coast, East Antarctica
Tetsuya P. Tamura, Daiki Nomura, Daisuke Hirano, Takeshi Tamura, Masaaki Kiuchi, Gen Hashida, Ryosuke Makabe, Kazuya Ono, Shuki Ushio, Kaihe Yamazaki, Yoshihiro Nakayama, Keigo D. Takahashi, Hiroko Sasaki, Hiroto Murase, Shigeru Aoki
Global Biogeochemical Cycles, 37, 9, American Geophysical Union (AGU), 2023年09月02日, ［査読有り］, ［責任著者］
研究論文（学術雑誌）, Abstract
To clarify the impacts of basal melting of the Antarctic ice sheet and biological productivity on biogeochemical processes in Antarctic coastal waters, concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA), inorganic nutrients, chlorophyll a, and stable oxygen isotopic ratios (δ18O) were measured from the offshore slope to the ice front of the Totten Ice Shelf (TIS) during the spring/summer of 2018, 2019, and 2020. Modified Circumpolar Deep Water (mCDW) intruded onto the continental shelf off the TIS and flowed along bathymetric troughs into the TIS cavity, where it formed a buoyant mixture with glacial meltwater from the ice shelf base. Physical oceanographic processes mostly determined the distributions of DIC, TA, and nutrient concentrations. However, photosynthesis and dilution by meltwater from sea ice and the ice shelf base decreased DIC, TA, and nutrient concentrations in surface water near the ice front. These causes also reduced the partial pressure of CO2 (pCO2) in surface water by more than 100 μatm with respect to mCDW in austral summer of 2018 and 2020, and the surface water became a strong CO2 sink for the atmosphere. Phytoplankton photosynthesis changed DIC and TA in a molar ratio of 106:16. Thus, pCO2 decreased mostly as a result of photosynthesis while dilution by glacial and sea ice meltwater had a small effect. The nutrient consumption ratio suggested that photosynthesis was stimulated by iron in the water column, supplied to the surface layer via buoyancy‐driven upwelling and basal ice shelf meltwater in addition to sea ice meltwater. - Distribution of stable oxygen isotope in seawater and implication on freshwater cycle off the coast from Wilkes to George V Land, East Antarctica
Shigeru Aoki, Kaihe Yamazaki, Daisuke Hirano, Daiki Nomura, Hiroto Murase
Progress in Oceanography, 217, 103101, 103101, Elsevier BV, 2023年09月, ［査読有り］
研究論文（学術雑誌） - Meltwater layer dynamics in a central Arctic lead: Effects of lead width, re-freezing, and mixing during late summer
Nomura, D, Kawaguchi, Y, Webb, A, Li, Y, Dall’osto, M, Schmidt, K, Droste, E. S, Chamberlain, E. J, Kolabutin, N, Shimanchuk, E, Hoppmann, M, Gallagher, M. R, Meyer, H, Mellat, M, Bauch, D, Gabarró, C, Smith, M. M, Inoue, J, Damm, E, Delille, B
Elementa, Science of the Anthropocene, 11, 1, 2023年05月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Biogeochemical characteristics of brash sea ice and icebergs during summer and autumn in the Indian sector of the Southern Ocean
Daiki Nomura, Reishi Sahashi, Keigo D. Takahashi, Ryosuke Makabe, Masato Ito, Manami Tozawa, Pat Wongpan, Ryo Matsuda, Masayoshi Sano, Michiyo Yamamoto-Kawai, Natsumi Nojiro, Aiko Tachibana, Norio Kurosawa, Masato Moteki, Takeshi Tamura, Shigeru Aoki, Hiroto Murase
Progress in Oceanography, 214, 103023, 103023, Elsevier BV, 2023年04月, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌） - Light Under Arctic Sea Ice in Observations and Earth System Models
Marion Lebrun, Martin Vancoppenolle, Gurvan Madec, Marcel Babin, Guislain Becu, Antonio Lourenço, Daiki Nomura, Frederic Vivier, Bruno Delille
Journal of Geophysical Research: Oceans, 128, 3, American Geophysical Union (AGU), 2023年03月02日, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - Significant nutrient consumption in the dark subsurface layer during a diatom bloom: a case study on Funka Bay, Hokkaido, Japan
Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki
Biogeosciences, 20, 2, 421, 438, Copernicus GmbH, 2023年01月27日, ［査読有り］, ［国際誌］
研究論文（学術雑誌）, Abstract. We conducted repetitive observations in Funka Bay,Hokkaido, Japan, on 15 February, 4 and 15 March, and 14 April 2019. Thediatom spring bloom peaked on 4 March and started declining on 15 March.Funka Bay winter water remained below 30 m depth, which was below thesurface mixed-layer and dark-layer depth (0.1 % of the surface photosynthetically active radiation, PAR, depth) on 4and 15 March. In the subsurface layer at depths of 30–50 m, concentrationsof NO3-, PO43-, and Si(OH)4 decreased by halfbetween these dates, even in the dark. Incubation experiments using thediatom Thalassiosira nordenskioeldii showed that this diatom could consume added nutrients in the dark atsubstantial rates after pre-culturing to deplete nutrients. Incubationexperiments using natural seawater collected in the growing phase of the bloom on 8 March 2022 also showed that nutrient-depleted phytoplankton could consumeadded nutrients in the dark. We excluded three physicalprocess – water mixing, diffusive transport, and subduction – as possible mainreasons for the decrease in nutrients in the subsurface layer. We concludethat the nutrient reduction in the subsurface layer (30–50 m) between 4 and15 March 2019 could be explained by nutrient consumption by diatoms in the dark in thatlayer. - The Interannual Variability of Sea Ice Area, Thickness, and Volume in the Southern Sea of Okhotsk and Its Likely Factors
Takenobu Toyota, Noriaki Kimura, Jun Nishioka, Masato Ito, Daiki Nomura, Humio Mitsudera
Journal of Geophysical Research: Oceans, 127, 12, American Geophysical Union (AGU), 2022年12月, ［査読有り］
英語, 研究論文（学術雑誌） - Factors controlling the precipitation of ikaite crystals within sea ice in a laboratory experiment
Haruka NAKAJIMA, Daiki NOMURA
Journal of the Japanese Society of Snow and Ice, 84, 6, 503, 514, Japanese Society of Snow and Ice, 2022年11月15日, ［査読有り］, ［責任著者］
研究論文（学術雑誌） - Dominant frazil ice production in the Cape Darnley polynya leading to Antarctic Bottom Water formation
Kay I. Ohshima, Yasushi Fukamachi, Masato Ito, Kazuki Nakata, Daisuke Simizu, Kazuya Ono, Daiki Nomura, Gen Hashida, Takeshi Tamura
Science Advances, 8, 42, American Association for the Advancement of Science (AAAS), 2022年10月21日, ［査読有り］
研究論文（学術雑誌）, Antarctic Bottom Water (AABW) occupies the abyssal layer of the world ocean and contributes to the global overturning circulation. It originates from dense shelf water, which forms from brine rejection during sea ice production. An important region of AABW formation has been identified off the Cape Darnley polynya. However, it remains unclear why and how high ice production leads to AABW formation. Using moored acoustic measurements and a satellite microwave algorithm, we reveal that underwater frazil ice dominates in the polynya. This underwater ice formation prevents heat-insulating surface-cover ice forming, thereby enabling efficient ice production. The high ice production in the nearshore and longer residence times create high-salinity source water for the AABW. Underwater frazil ice occurs as long as strong winds continue and occasionally penetrates depths of at least 80 m. Deep-penetrating frazil ice is particularly prominent in this polynya, while it also occurs in other Antarctic coastal polynyas. - First results of the ARIEL L-band radiometer on the MOSAiC Arctic Expedition during the late summer and autumn period
Carolina Gabarró, Pau Fabregat, Ferran Hernández-Macià, Roger Jove, Joaquin Salvador, Gunnar Spreen, Linda Thielke, Ruzica Dadic, Marcus Huntemann, Nikolai Kolabutin, Daiki Nomura, Henna-Reetta Hannula, Martin Schneebeli
Elementa: Science of the Anthropocene, 10, 1, University of California Press, 2022年09月23日, ［査読有り］
研究論文（学術雑誌）, Arctic sea ice is changing rapidly. Its retreat significantly impacts Arctic heat fluxes, ocean currents, and ecology, warranting the continuous monitoring and tracking of changes to sea ice extent and thickness. L-band (1.4 GHz) microwave radiometry can measure sea ice thickness for thin ice ≤1 m, depending on salinity and temperature. The sensitivity to thin ice makes L-band measurements complementary to radar altimetry which can measure the thickness of thick ice with reasonable accuracy. During the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, we deployed the mobile ARIEL L-band radiometer on the sea ice floe next to research vessel Polarstern to study the sensitivity of the L-band to different sea ice parameters (e.g., snow and ice thickness, ice salinity, ice and snow temperature), with the aim to help improve/validate current microwave emission models. Our results show that ARIEL is sensitive to different types of surfaces (ice, leads, and melt ponds) and to ice thickness up to 70 cm when the salinity of the sea ice is low. The measurements can be reproduced with the Burke emission model when in situ snow and ice measurements for the autumn transects were used as model input. The correlation coefficient for modeled Burke brightness temperature (BT) versus ARIEL measurements was approximately 0.8. The discrepancy between the measurements and the model is about 5%, depending on the transects analyzed. No explicit dependence on snow depth was detected. We present a qualitative analysis for thin ice observations on leads. We have demonstrated that the ARIEL radiometer is an excellent field instrument for quantifying the sensitivity of L-band radiometry to ice and snow parameters, leading to insights that can enhance sea ice thickness retrievals from L-band radiometer satellites (such as Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP)) and improve estimates of Arctic sea-ice thickness changes on a larger scale. - Methane release from open leads and new ice following an Arctic winter storm event
Anna Silyakova, Daiki Nomura, Marie Kotovitch, Agneta Fransson, Bruno Delille, Melissa Chierici, Mats A. Granskog
Polar Science, 33, 100874, 100874, Elsevier BV, 2022年09月, ［査読有り］, ［責任著者］
研究論文（学術雑誌） - Turbulent Mixing During Late Summer in the Ice–Ocean Boundary Layer in the Central Arctic Ocean: Results From the MOSAiC Expedition
Yusuke Kawaguchi, Zoé Koenig, Daiki Nomura, Mario Hoppmann, Jun Inoue, Ying‐Chih Fang, Kirstin Schulz, Michael Gallagher, Christian Katlein, Marcel Nicolaus, Benjamin Rabe
Journal of Geophysical Research: Oceans, 127, 8, American Geophysical Union (AGU), 2022年08月, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - Effects of the glacial meltwater supply on carbonate chemistry in Bowdoin Fjord, Northwestern Greenland
Takahito Horikawa, Daiki Nomura, Naoya Kanna, Yasushi Fukamachi, Shin Sugiyama
Frontiers in Marine Science, 9, Frontiers Media SA, 2022年07月22日, ［査読有り］, ［責任著者］, ［国際誌］
研究論文（学術雑誌）, To understand the effects of the glacial meltwater supply on carbonate chemistry and the air–sea CO2 flux within the fjord, water samples were collected in Bowdoin Fjord in northwestern Greenland for dissolved inorganic carbon (DIC) concentration, total alkalinity (TA), oxygen isotopic ratio (δ18O), and chlorophyll a concentration analyses in the summers of 2016 and 2017. The partial pressure of CO2 (pCO2) in surface water, calculated from DIC and TA, was less than 200 µatm, and was significantly lower than that in the atmosphere (399 ± 3 µatm). Therefore, surface water of the fjord acts as sink for CO2 in the atmosphere (–4.9 ± 0.7 mmol m–2 d–1). To evaluate the effects of freshwater and land-derived substances by glacial meltwater on pCO2 in the fjord, we calculated the changes of pCO2 in salinity and carbonate chemistry that would result from the inflow of glacial meltwater into the fjord. The calculated pCO2 was high near the calving front, where the contribution of glacier meltwater was significant. Examination of the relationship between salinity-normalized DIC and TA, which was considered DIC and TA input from the land, suggested that the land-derived high pCO2 freshwater affected mainly by the remineralization of the organic matter by bacterial activity was supplied to the Bowdoin Fjord. - Effects of Snow and Remineralization Processes on Nutrient Distributions in Multi‐Year Antarctic Landfast Sea Ice
Reishi Sahashi, Daiki Nomura, Takenobu Toyota, Manami Tozawa, Masato Ito, Pat Wongpan, Kazuya Ono, Daisuke Simizu, Kazuhiro Naoki, Yuichi Nosaka, Takeshi Tamura, Shigeru Aoki, Shuki Ushio
Journal of Geophysical Research: Oceans, 127, 7, American Geophysical Union (AGU), 2022年07月, ［査読有り］, ［責任著者］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - Primary productivity and phytoplankton community structure in surface waters of the western subarctic Pacific and the Bering Sea during summer with reference to bloom stages
Hisatomo Waga, Amane Fujiwara, Toru Hirawake, Koji Suzuki, Kazuhiro Yoshida, Hiroto Abe, Daiki Nomura
Progress in Oceanography, 201, 102738, 102738, Elsevier BV, 2022年02月, ［査読有り］
英語, 研究論文（学術雑誌） - Nutrient consumption by diatoms in the dark subsurface layer of Funka Bay, Hokkaido, Japan
Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, Atsushi Ooki
Copernicus GmbH, 2022年01月06日, ［査読有り］
Abstract. We conducted time-series observations in Funka Bay, Hokkaido, Japan, from 15 February to 14 April 2019. The diatom spring bloom peaked on 4 March and started declining on 15 March. Funka Bay winter water remained below 30-m depth, which was below the surface mixed-layer and dark-zone depths on both dates. At depths of 30–50 m, concentrations of NO3–, PO43–, and Si(OH)4 decreased by half between these dates even in darkness. Incubation experiments using the diatom Thalassiosira nordenskioeldii showed that this diatom could consume nutrients in darkness at substantial rates. We conclude that the nutrient reduction in the subsurface layer (30–50 m) could be explained by dark consumption by diatoms that had been growing in the surface waters and then sank to the subsurface layer. We believe that this is the first study to present observational evidence for the consumption of the main nutrients by diatoms in the dark subsurface layer during the spring bloom. Nutrient consumption in this layer might have a substantial influence on the primary production during and after the spring bloom. - Isoprene production in the water column and sediment in Funka Bay, Hokkaido, Japan
Atsushi Ooki, Naoya Miyashita, Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu
GEOCHEMICAL JOURNAL, 56, 5, 142, 150, Geochemical Society of Japan, 2022年, ［査読有り］
研究論文（学術雑誌） - Atmosphere-sea ice-ocean interaction study in Saroma-ko Lagoon, Hokkaido, Japan 2021
Daiki NOMURA, Hiroki IKAWA, Yusuke KAWAGUCHI, Naoya KANNA, Tatsuya KAWAKAMI, Yuichi NOSAKA, Sachi UMEZAWA, Manami TOZAWA, Takahito HORIKAWA, Reishi SAHASHI, Taichi NOSHIRO, Ibuki KABA, Makoto OZAKI, Fumiyoshi KONDO, Keisuke ONO, Itsuka S. YABE, Eun Yae SON, Takahiro TOYODA, Sohiko KAMEYAMA, Changqing WANG, Hajime OBATA, Atsushi OOKI, Hiromichi UENO, Akihide KASAI
Bulletin of Glaciological Research, 40, 1, 17, 公益社団法人 日本雪氷学会, 2022年, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Seasonal Variations and Drivers of Surface Ocean pCO2 in the Seasonal Ice Zone of the Eastern Indian Sector, Southern Ocean
Manami Tozawa, Daiki Nomura, Shin‐ichiro Nakaoka, Masaaki Kiuchi, Kaihe Yamazaki, Daisuke Hirano, Shigeru Aoki, Hiroko Sasaki, Hiroto Murase
Journal of Geophysical Research: Oceans, 127, 1, American Geophysical Union (AGU), 2022年01月, ［査読有り］
英語, 研究論文（学術雑誌） - Decadal vision in oceanography 2021: Polar oceans
Michiyo Yamamoto-Kawai, Takeshi Tamura, Eiji Watanabe, Jun Nishioka, Daiki Nomura, Ryusuke Makabe, Kohei Mizobata, Yasunaka Sayaka
Oceanography in Japan, 30, 5, 159, 178, The Oceanographic Society of Japan, 2021年11月15日, ［査読有り］
研究論文（学術雑誌） - Salinity regime of the northwestern Bering Sea shelf
Hiroto Abe, Daiki Nomura, Toru Hirawake
Progress in Oceanography, 198, 102675, 102675, Elsevier BV, 2021年11月, ［査読有り］
研究論文（学術雑誌） - Iron and nutrient dynamics along the East Kamchatka Current, western Bering Sea Basin and Gulf of Anadyr
Jun Nishioka, Toru Hirawake, Daiki Nomura, Youhei Yamashita, Kazuya Ono, Aiko Murayama, Alexey Shcherbinin, Yuri N. Volkov, Humio Mitsudera, Naoto Ebuchi, Masaaki Wakatsuchi, Ichiro Yasuda
Progress in Oceanography, 198, 102662, 102662, Elsevier BV, 2021年11月, ［査読有り］, ［国際共著］
研究論文（学術雑誌） - Climate change impacts on sea-ice ecosystems and associated ecosystem services
Nadja S. Steiner, Jeff Bowman, Karley Campbell, Melissa Chierici, Eeva Eronen-Rasimus, Marianne Falardeau, Hauke Flores, Agneta Fransson, Helena Herr, Stephen J Insley, Hanna M. Kauko, Delphine Lannuzel, Lisa Loseto, Amanda Lynnes, Andy Majewski, Klaus M. Meiners, Lisa A. Miller, Loïc N. Michel, Sebastien Moreau, Melissa Nacke, Daiki Nomura, Letizia Tedesco, Jan Andries van Franeker, Maria A van Leeuwe, Pat Wongpan
Elementa: Science of the Anthropocene, 9, 1, University of California Press, 2021年10月13日, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌）, A rigorous synthesis of the sea-ice ecosystem and linked ecosystem services highlights that the sea-ice ecosystem supports all 4 ecosystem service categories, that sea-ice ecosystems meet the criteria for ecologically or biologically significant marine areas, that global emissions driving climate change are directly linked to the demise of sea-ice ecosystems and its ecosystem services, and that the sea-ice ecosystem deserves specific attention in the evaluation of marine protected area planning. The synthesis outlines (1) supporting services, provided in form of habitat, including feeding grounds and nurseries for microbes, meiofauna, fish, birds and mammals (particularly the key species Arctic cod, Boreogadus saida, and Antarctic krill, Euphausia superba, which are tightly linked to the sea-ice ecosystem and transfer carbon from sea-ice primary producers to higher trophic level fish, mammal species and humans); (2) provisioning services through harvesting and medicinal and genetic resources; (3) cultural services through Indigenous and local knowledge systems, cultural identity and spirituality, and via cultural activities, tourism and research; (4) (climate) regulating services through light regulation, the production of biogenic aerosols, halogen oxidation and the release or uptake of greenhouse gases, for example, carbon dioxide. The ongoing changes in the polar regions have strong impacts on sea-ice ecosystems and associated ecosystem services. While the response of sea-ice–associated primary production to environmental change is regionally variable, the effect on ice-associated mammals and birds is predominantly negative, subsequently impacting human harvesting and cultural services in both polar regions. Conservation can help protect some species and functions. However, the key mitigation measure that can slow the transition to a strictly seasonal ice cover in the Arctic Ocean, reduce the overall loss of sea-ice habitats from the ocean, and thus preserve the unique ecosystem services provided by sea ice and their contributions to human well-being is a reduction in carbon emissions. - 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, 2021年09月, ［査読有り］
研究論文（学術雑誌） - Formation of dense shelf water associated with sea ice freezing in the Gulf of Anadyr estimated with oxygen isotopic ratios
Daiki Nomura, Hiroto Abe, Toru Hirawake, Atsushi Ooki, Youhei Yamashita, Aiko Murayama, Kazuya Ono, Jun Nishioka
Progress in Oceanography, 196, 102595, 102595, Elsevier BV, 2021年08月, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌） - The Effect of Basal Melting of the Shirase Glacier Tongue on the CO 2 System in Lützow‐Holm Bay, East Antarctica
Masaaki Kiuchi, Daiki Nomura, Daisuke Hirano, Takeshi Tamura, Gen Hashida, Shuki Ushio, Daisuke Simizu, Kazuya Ono, Shigeru Aoki
Journal of Geophysical Research: Biogeosciences, 126, 5, American Geophysical Union (AGU), 2021年05月, ［査読有り］, ［責任著者］
研究論文（学術雑誌） - Effects of lead width variation, re-freezing and mixing events on lead water structure in the central Arctic
Daiki Nomura, Alison Web, Yuhong Li, Manuel Dall’osto, Katrin Schmidt, Elise Droste, Emelia Chamberlain, Yusuke Kawaguchi, Jun Inoue, Ellen Damm, Bruno Delille
Copernicus GmbH, 2021年03月04日, ［査読有り］, ［筆頭著者, 責任著者］
<p>We undertook a lead survey during the international drift campaign MOSAiC, Leg 5 (from 22 August to 17 September 2020) to understand the effects of lead width variation, re-freezing, and mixing events on lead water vertical structure. At the beginning of the survey period, the freshwater layer was occupied for the top 1 m depth and there were strong vertical gradients in temperature, salinity, and dissolved oxygen (DO) within 1 m depth: from 0.0&#176;C to &#8211;1.6&#176;C for temperature, from 0.0 to 31.4 psu for salinity, and 10.5 to 13.5 mg L<sup>&#8211;1</sup> for DO. A strong DO minimum layer corresponded with a salinity of 25 psu, and usually occurred at the freshwater&#8211;seawater interface at approx. 1 m depth, most likely as a result of an accumulation of organic matter and ongoing degradation/respiration processes at this interface. However, during the survey period, these strong gradients weakened and reduced the freshwater layer thickness (FLT). In the first half of the sampling period (until 4 September), FLT changed due to variations in lead width: as lead width increased, FLT decreased due to a stretching of the freshwater layer. In the second half of the sampling period, FLT was controlled by the surface ice formation (re-freezing) and mixing processes along the lower boundary of the freshwater layer. Surface ice formation removed freshwater and the formation of surface ice (about 0.2 m thick) explains 20% of the reduction of FLT. The remaining 80% of the reduction of FLT was due to the mixing process within the water column that was initiated by cooling and re-freezing. This mixing process diluted the salinity from 31.6 to 29.3 psu in the water below freshwater layer towards the end of the survey period. Our results indicate that lead water structure can change rapidly and dynamically and that this has significant effects on the biogeochemical exchange between lead systems and the atmosphere.</p> - Interfacial generation of internal waves and turbulent heat flux due to enhanced inertial motion for deformed sea-ice floe: Preliminary results from MOSAiC expedition
Yusuke Kawaguchi, Zoe Koenig, Mario Hoppman, Daiki Nomura, Mats Granskog, Jun Inoue, Christian Katlein, Marcel Nicolaus
Copernicus GmbH, 2021年03月04日, ［査読有り］
<p>Sea-ice drift becomes most energetic at last moment in summer when refreezing is about to onset. Perennial ice floes, surviving over all seasons, tend to experience a number of deformation events over yearlong drift, with uneven distribution in thickness. Deformed ice floes protrude tall keels into water of ice-ocean boundary, and then stir it up. Consequently, combination of fast ice drift and deformation-experienced perennial ice could be a primary source of momentum/thermal energy for upper waters through propagation of internal waves. In this study, during MOSAiC expedition, we attempted to perform direct observation of wave generation in ice-ocean boundary layer underneath a drifting ice floe in the central Arctic Ocean. Time series of turbulent signals, represented by Reynolds stress <u'w'> and eddy heat flux <w'T'>, were obtained by an eddy covariance system (ECS), coupling a high-frequency (34 Hz) single-point current meter and a temperature sensor. Vertical/temporal properties of near-inertial waves were obtained by a downward-looking ADCP, collocated with ECS on the same ice floe. At same time, a triangle of high-precision GPS systems tracked ice movement to represent mean drift speed, rotation and deformation about the same floe seamlessly in time. Preliminary analyses of those combined data suggested that pronounced signals of inertial motion occurred in early September of 2020 as sheer ice keels dragged underlying waters, stratified by accumulation of melt water. It then allowed occurrence of near-inertial internal waves that tend to be trapped within the interfacial boundary layer, located within top 20 m. At the conference, we will present latest and quantitative knowledges from the MOSAiC expedition.</p> - Rapidly changing glaciers, ocean and coastal environments, and their impact on human society in the Qaanaaq region, northwestern Greenland
Shin Sugiyama, Naoya Kanna, Daiki Sakakibara, Takuto Ando, Izumi Asaji, Ken Kondo, Yefan Wang, Yoshiki Fujishi, Shungo Fukumoto, Evgeniy Podolskiy, Yasushi Fukamachi, Minori Takahashi, Sumito Matoba, Yoshinori Iizuka, Ralf Greve, Masato Furuya, Kazutaka Tateyama, Tatsuya Watanabe, Shintaro Yamasaki, Atsushi Yamaguchi, Bungo Nishizawa, Kohei Matsuno, Daiki Nomura, Yuta Sakuragi, Yoshimasa Matsumura, Yoshihiko Ohashi, Teruo Aoki, Masashi Niwano, Naotaka Hayashi, Masahiro Minowa, Guillaume Jouvet, Eef van Dongen, Andreas Bauder, Martin Funk, Anders Anker Bjørk, Toku Oshima
Polar Science, 27, 100632, 100632, Elsevier BV, 2021年03月, ［査読有り］, ［国際共著］
研究論文（学術雑誌） - The future of Arctic sea-ice biogeochemistry and ice-associated ecosystems
Delphine Lannuzel, Letizia Tedesco, Maria van Leeuwe, Karley Campbell, Hauke Flores, Bruno Delille, Lisa Miller, Jacqueline Stefels, Philipp Assmy, Jeff Bowman, Kristina Brown, Giulia Castellani, Melissa Chierici, Odile Crabeck, Ellen Damm, Brent Else, Agneta Fransson, François Fripiat, Nicolas-Xavier Geilfus, Caroline Jacques, Elizabeth Jones, Hermanni Kaartokallio, Marie Kotovitch, Klaus Meiners, Sébastien Moreau, Daiki Nomura, Ilka Peeken, Janne-Markus Rintala, Nadja Steiner, Jean-Louis Tison, Martin Vancoppenolle, Fanny Van der Linden, Marcello Vichi, Pat Wongpan
Nature Climate Change, 10, 11, 983, 992, Springer Science and Business Media LLC, 2020年11月, ［査読有り］, ［国際共著］
研究論文（学術雑誌） - Iron Supply by Subglacial Discharge Into a Fjord Near the Front of a Marine‐Terminating Glacier in Northwestern Greenland
Naoya Kanna, Shin Sugiyama, Yasushi Fukamachi, Daiki Nomura, Jun Nishioka
Global Biogeochemical Cycles, 34, 10, American Geophysical Union (AGU), 2020年10月, ［査読有り］
研究論文（学術雑誌） - Implications of Sea Ice Management for Arctic Biogeochemistry
Lisa Miller, Francois Fripiat, Sebastien Moreau, Daiki Nomura, Jacqueline Stefels, Nadja Steiner, Letizia Tedesco, Martin Vancoppenolle
Eos, 101, American Geophysical Union (AGU), 2020年09月30日, ［査読有り］, ［国際共著］
研究論文（学術雑誌）, Geoengineering strategies to slow sea ice melting would affect not only Earth's climate but also the biology and chemistry of the oceans, atmosphere, and ice. - Using under-ice hyperspectral transmittance to determine land-fast sea-ice algal biomass in Saroma-ko Lagoon, Hokkaido, Japan
Pat Wongpan, Daiki Nomura, Takenobu Toyota, Tomonori Tanikawa, Klaus M. Meiners, Tomomi Ishino, Tetsuya P. Tamura, Manami Tozawa, Yuichi Nosaka, Toru Hirawake, Atsushi Ooki, Shigeru Aoki
Annals of Glaciology, 61, 83, 1, 10, 2020年09月24日, ［査読有り］
英語, 研究論文（学術雑誌） - Strong biological carbon uptake and carbonate chemistry associated with dense shelf water outflows in the Cape Darnley polynya, East Antarctica
Kan Murakami, Daiki Nomura, Gen Hashida, Shin ichiro Nakaoka, Yujiro Kitade, Daisuke Hirano, Toru Hirawake, Kay I. Ohshima
Marine Chemistry, 225, 103842, 103842, Elsevier BV, 2020年09月10日, ［査読有り］, ［責任著者］
研究論文（学術雑誌） - Influence of glacial water and carbonate minerals on wintertime sea-ice biogeochemistry and the CO2 system in an Arctic fjord in Svalbard
Agneta Fransson, Melissa Chierici, Daiki Nomura, Mats A. Granskog, Svein Kristiansen, Tõnu Martma, Gernot Nehrke
Annals of Glaciology, 1, 21, Cambridge University Press (CUP), 2020年08月13日, ［査読有り］, ［国際共著］
研究論文（学術雑誌）,Abstract
The effect of freshwater sources on wintertime sea-ice CO2 processes was studied from the glacier front to the outer Tempelfjorden, Svalbard, in sea ice, glacier ice, brine and snow. March–April 2012 was mild, and the fjord was mainly covered with drift ice, in contrast to the observed thicker fast ice in the colder April 2013. This resulted in different physical and chemical properties of the sea ice and under-ice water. Data from stable oxygen isotopic ratios and salinity showed that the sea ice at the glacier front in April 2012 contained on average 54% of frozen-in glacial meltwater. This was five times higher than in April 2013, where the ice was frozen seawater. In April 2012, the largest excess of sea-ice total alkalinity (A T), carbonate ion ([CO32−]) and bicarbonate ion concentrations ([HCO3−]) relative to salinity was mainly related to dissolved dolomite and calcite incorporated during freezing of mineral-enriched glacial water. In April 2013, the excess of these variables was mainly due to ikaite dissolution as a result of sea-ice processes. Dolomite dissolution increased sea-iceA T twice as much as ikaite and calcite dissolution, implying different buffering capacity and potential for ocean CO2 uptake in a changing climate. - Solidification effects of snowfall on sea-ice freeze-up: results from an onsite experimental study
Takenobu Toyota, Takashi Ono, Tomonori Tanikawa, Pat Wongpan, Daiki Nomura
Annals of Glaciology, 61, 83, 1, 10, Cambridge University Press (CUP), 2020年07月14日, ［査読有り］, ［国際共著］
研究論文（学術雑誌）,Abstract
Although the effects of snow during sea-ice growth have been investigated for sea ice which is thick enough to accommodate dry snow, those for thin sea ice have not been paid much attention due to the difficulty in observing them. Observations are complicated by the presence of slush and its subsequent freeze-up, and the surface heat budget might be sensitive to the additional ice thickness. An onsite short-term land fast sea-ice freeze-up experiment in the Saroma-ko Lagoon, Hokkaido, Japan was carried out to examine the effects of snowfall on the structure and surface heat budget of thin sea ice, based on observational results and a 1-D thermodynamic model. We found that snowfall contributes to the solidification of the surface slush layer, contributing ice thickness that is comparable to the snowfall amount and affecting the crystal texture significantly. On the other hand, the basal ice growth rate and turbulent heat flux were not significantly affected, being <3.1 × 10−8 m s−1 and 3 W m−2, respectively. This finding may validate the omission in past studies of snow effect in estimating ice production rates in polynyas and has implications about the reconstruction of growth history from sample analysis. - Physical and biological properties of early winter Antarctic sea ice in the Ross Sea
Jean-Louis Tison, Ted Maksym, Alexander D. Fraser, Matthew Corkill, Noriaki Kimura, Yuichi Nosaka, Daiki Nomura, Martin Vancoppenolle, Steve Ackley, Sharon Stammerjohn, Sarah Wauthy, Fanny Van der Linden, Gauthier Carnat, Célia Sapart, Jeroen de Jong, François Fripiat, Bruno Delille
Annals of Glaciology, 1, 19, Cambridge University Press (CUP), 2020年06月24日, ［査読有り］, ［国際共著］
研究論文（学術雑誌）,Abstract
This work presents the results of physical and biological investigations at 27 biogeochemical stations of early winter sea ice in the Ross Sea during the 2017 PIPERS cruise. Only two similar cruises occurred in the past, in 1995 and 1998. The year 2017 was a specific year, in that ice growth in the Central Ross Sea was considerably delayed, compared to previous years. These conditions resulted in lower ice thicknesses and Chl-a burdens, as compared to those observed during the previous cruises. It also resulted in a different structure of the sympagic algal community, unusually dominated byPhaeocystis rather than diatoms. Compared to autumn-winter sea ice in the Weddell Sea (AWECS cruise), the 2017 Ross Sea pack ice displayed similar thickness distribution, but much lower snow cover and therefore nearly no flooding conditions. It is shown that contrasted dynamics of autumnal-winter sea-ice growth between the Weddell Sea and the Ross Sea impacted the development of the sympagic community. Mean/median ice Chl-a concentrations were 3–5 times lower at PIPERS, and the community status there appeared to be more mature (decaying?), based on Phaeopigments/Chl-a ratios. These contrasts are discussed in the light of temporal and spatial differences between the two cruises. - Snow property controls on modelled Ku-band altimeter estimates of first-year sea ice thickness: Case studies from the Canadian and Norwegian Arctic
Nandan V, Scharien R. K, Geldsetzer T, Kwok R, Yackel J. J, Mahmud M. S, Rösel A, Tonboe R, Granskog M, Willatt R, Stroeve J, Nomura D, Frey M.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 13, 1082, 1096, 2020年, ［査読有り］, ［国際共著］ - Saroma-ko Lagoon Observations for sea ice Physico-chemistry and Ecosystems 2019 (SLOPE2019)
Daiki NOMURA, Pat WONGPAN, Takenobu TOYOTA, Tomonori TANIKAWA, Yusuke KAWAGUCHI, Takashi ONO, Tomomi ISHINO, Manami TOZAWA, Tetsuya P. TAMURA, Itsuka S. YABE, Eun Yae SON, Frederic VIVIER, Antonio LOURENCO, Marion LEBRUN, Yuichi NOSAKA, Toru HIRAWAKE, Atsushi OOKI, Shigeru AOKI, Brent ELSE, Francois FRIPIAT, Jun INOUE, Martin VANCOPPENOLLE
Bulletin of Glaciological Research, 38, 0, 1, 12, Japanese Society of Snow and Ice, 2020年, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］
研究論文（学術雑誌） - Fostering multidisciplinary research on interactions between chemistry, biology, and physics within the coupled cryosphere-atmosphere system
Jennie L. Thomas, Jochen Stutz, Markus M. Frey, Thorsten Bartels-Rausch, Katye Altieri, Foteini Baladima, Jo Browse, Manuel Dall’Osto, Louis Marelle, Jeremie Mouginot, Jennifer G. Murphy, Daiki Nomura, Kerri A. Pratt, Megan D. Willis, Paul Zieger, Jon Abbatt, Thomas A. Douglas, Maria Cristina Facchini, James France, Anna E. Jones, Kitae Kim, Patricia A. Matrai, V. Faye McNeill, Alfonso Saiz-Lopez, Paul Shepson, Nadja Steiner, Kathy S. Law, Steve R. Arnold, Bruno Delille, Julia Schmale, Jeroen E. Sonke, Aurélien Dommergue, Didier Voisin, Megan L. Melamed, Jessica Gier
Elem Sci Anth, 7, 1, 58, 58, University of California Press, 2019年12月30日, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - Isoprene production in seawater of Funka Bay, Hokkaido, Japan
Atsushi Ooki, Ryuta Shida, Masashi Otsu, Hiroji Onishi, Naoto Kobayashi, Takahiro Iida, Daiki Nomura, Kota Suzuki, Hideyoshi Yamaoka, Tetsuya Takatsu
Journal of Oceanography, 75, 6, 485, 501, Springer Science and Business Media LLC, 2019年12月, ［査読有り］
研究論文（学術雑誌） - The effect of melting treatments on the assessment of biomass and nutrients in sea ice (Saroma-ko lagoon, Hokkaido, Japan)
Roukaerts A, Nomura D, Deman F, Hattori H, Dehairs F, Fripiat F
Polar Biology, 42, 347–356, 2019., 2019年, ［査読有り］, ［国際共著］ - Production of Dibromomethane and Changes in the Bacterial Community in Bromoform-Enriched Seawater
Takafumi Kataoka, Atsushi Ooki, Daiki Nomura
Microbes and Environments, 34, 2, 215, 218, Japanese Society of Microbial Ecology, 2019年, ［査読有り］, ［最終著者］
研究論文（学術雑誌） - Effects of glacier and sea ice melting on the biogeochemical cycles in the surface water of the Arctic Ocean
Nomura D, Kanna N, Ooki A
Chikyu-Kagaku (Geochemistry), In Japanese with English abstract, figures, and table, 53, 149-158, doi:10.14934/chikyukagaku.53.149, 2019., 2019年, ［査読有り］, ［筆頭著者, 責任著者］ - Biogeochemistry of bromine and organic sulfur compounds in the Arctic region
Kameyama S, Ooki A, Nomura D
Chikyu-Kagaku (Geochemistry), In Japanese with English abstract, and figures. 53, 159-171, doi:10.14934/chikyukagaku.53.159, 2019., 2019年, ［査読有り］, ［最終著者］ - Chlorophyll-a in Antarctic Landfast Sea Ice: A First Synthesis of Historical Ice Core Data
K. M. Meiners, M. Vancoppenolle, G. Carnat, G. Castellani, B. Delille, D. Delille, G. S. Dieckmann, H. Flores, F. Fripiat, M. Grotti, B. A. Lange, D. Lannuzel, A. Martin, A. McMinn, D. Nomura, I. Peeken, P. Rivaro, K. G. Ryan, J. Stefels, K. M. Swadling, D. N. Thomas, J.-L. Tison, P. van der Merwe, M. A. van Leeuwe, C. Weldrick, E. J. Yang
Journal of Geophysical Research: Oceans, 123, 11, 8444, 8459, American Geophysical Union (AGU), 2018年11月, ［査読有り］, ［国際共著］
研究論文（学術雑誌） - CO2 flux over young and snow-covered Arctic pack ice in winter and spring
Daiki Nomura, Mats A. Granskog, Agneta Fransson, Melissa Chierici, Anna Silyakova, Kay I. Ohshima, Lana Cohen, Bruno Delille, Stephen R. Hudson, Gerhard S. Dieckmann
Biogeosciences, 15, 11, 3331, 3343, Copernicus GmbH, 2018年06月05日, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］
研究論文（学術雑誌）, Abstract. Rare CO2 flux measurements from Arctic pack ice show that two types of ice contribute to the release of CO2 from the ice to the atmosphere during winter and spring: young, thin ice with a thin layer of snow and older (several weeks), thicker ice with thick snow cover. Young, thin sea ice is characterized by high salinity and high porosity, and snow-covered thick ice remains relatively warm ( > −7.5 °C) due to the insulating snow cover despite air temperatures as low as −40 °C. Therefore, brine volume fractions of these two ice types are high enough to provide favorable conditions for gas exchange between sea ice and the atmosphere even in mid-winter. Although the potential CO2 flux from sea ice decreased due to the presence of the snow, the snow surface is still a CO2 source to the atmosphere for low snow density and thin snow conditions. We found that young sea ice that is formed in leads without snow cover produces CO2 fluxes an order of magnitude higher than those in snow-covered older ice (+1.0 ± 0.6 mmol C m−2 day−1 for young ice and +0.2 ± 0.2 mmol C m−2 day−1 for older ice). - Upwelling of Macronutrients and Dissolved Inorganic Carbon by a Subglacial Freshwater Driven Plume in Bowdoin Fjord, Northwestern Greenland
Naoya Kanna, Shin Sugiyama, Yoshihiko Ohashi, Daiki Sakakibara, Yasushi Fukamachi, Daiki Nomura
Journal of Geophysical Research: Biogeosciences, 123, 5, 1666, 1682, American Geophysical Union (AGU), 2018年05月, ［査読有り］, ［最終著者］
研究論文（学術雑誌） - Influence of Sea Ice Crack Formation on the Spatial Distribution of Nutrients and Microalgae in Flooded Antarctic Multiyear Ice
Daiki Nomura, Shigeru Aoki, Daisuke Simizu, Takahiro Iida
Journal of Geophysical Research: Oceans, 123, 2, 939, 951, American Geophysical Union (AGU), 2018年02月, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌） - Effects of sea ice freezing and melting on air-sea CO2 exchange
Nomura D
Archives of Atmospheric Chemistry Research, In Japanese, 38, 038A03, 2018., 2018年, ［査読有り］, ［筆頭著者, 責任著者］ - Biogeochemical Impact of Snow Cover and Cyclonic Intrusions on the Winter Weddell Sea Ice Pack
J.‐L. Tison, S. Schwegmann, G. Dieckmann, J.‐M. Rintala, H. Meyer, S. Moreau, M. Vancoppenolle, D. Nomura, S. Engberg, L. J. Blomster, S. Hendricks, C. Uhlig, A.‐M. Luhtanen, J. de Jong, J. Janssens, G. Carnat, J. Zhou, B. Delille
Journal of Geophysical Research: Oceans, 122, 12, 9548, 9571, American Geophysical Union (AGU), 2017年12月, ［査読有り］, ［国際共著］
研究論文（学術雑誌） - Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes
François Fripiat, Klaus M. Meiners, Martin Vancoppenolle, Stathys Papadimitriou, David N. Thomas, Stephen F. Ackley, Kevin R. Arrigo, Gauthier Carnat, Stefano Cozzi, Bruno Delille, Gerhard S. Dieckmann, Robert B. Dunbar, Agneta Fransson, Gerhard Kattner, Hilary Kennedy, Delphine Lannuzel, David R. Munro, Daiki Nomura, Janne-Markus Rintala, Véronique Schoemann, Jacqueline Stefels, Nadja Steiner, Jean-Louis Tison
Elem Sci Anth, 5, 0, 13, 13, University of California Press, 2017年03月29日, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - Effect of elevated CO 2 concentration on microalgal communities in Antarctic pack ice
Thomas Coad, Andrew McMinn, Daiki Nomura, Andrew Martin
Deep Sea Research Part II: Topical Studies in Oceanography, 131, 160, 169, 2016年09月, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - DMSP and DMS cycling within Antarctic sea ice during the winter-spring transition
E. Damm, D. Nomura, A. Martin, G. S. Dieckmann, K. M. Meiners
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 131, 150, 159, 2016年09月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - On the extraordinary snow on the sea ice off East Antarctica in late winter, 2012
Takenobu Toyota, Robert Massom, Olivier Lecomte, Daiki Nomura, Petra Heil, Takeshi Tamura, Alexander D. Fraser
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 131, 53, 67, 2016年09月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Potential changes in feeding behavior of Antarctic fish, Pseudotrematomus bernacchii (Boulenger, 1902) on the East Ongul Island, Antarctica
Suchana Chavanich, Voranop Viyakarn, Daiki Nomura, Kentaro Watanabe
POLAR SCIENCE, 9, 4, 389, 392, 2015年12月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - A global-scale map of isoprene and volatile organic iodine in surface seawater of the Arctic, Northwest Pacific, Indian, and Southern Oceans
Atsushi Ooki, Daiki Nomura, Shigeto Nishino, Takashi Kikuchi, Yoko Yokouchi
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 120, 6, 4108, 4128, 2015年06月, ［査読有り］
英語, 研究論文（学術雑誌） - Effect of glacial drainage water on the CO2 system and ocean acidification state in an Arctic tidewater-glacier fjord during two contrasting years
Agneta Fransson, Melissa Chierici, Daiki Nomura, Mats A. Granskog, Svein Kristiansen, Tonu Martma, Gernot Nehrke
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 120, 4, 2413, 2429, 2015年04月, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Methods for biogeochemical studies of sea ice: The state of the art, caveats, and recommendations
Lisa A. Miller, Francois Fripiat, Brent G.T. Else, Jeff S. Bowman, Kristina A. Brown, R. Eric Collins, Marcela Ewert, Agneta Fransson, Michel Gosselin, Delphine Lannuzel, Klaus M. Meiners, Christine Michel, Jun Nishioka, Daiki Nomura, Stathys Papadimitriou, Lynn M. Russell, Lise Lotte Sørensen, David N. Thomas, Jean-Louis Tison, Maria A. van Leeuwe, Martin Vancoppenolle, Eric W. Wolff, Jiayun Zhou
Elementa: Science of the Anthropocene, 3, 000038, 000038, University of California Press, 2015年01月23日, ［査読有り］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - 2012年東南極域海氷上で観測された異常積雪深に関する事例解析
豊田 威信, R. Massom, O. Lecomte, 野村 大樹, P. Heil, 田村 岳史, A. Fraser
雪氷研究大会講演要旨集, 2015, 32, 32, 公益社団法人 日本雪氷学会／日本雪工学会, 2015年
日本語 - Evidence for significant protein-like dissolved organic matter accumulation in Sea of Okhotsk sea ice
Mats A. Granskog, Daiki Nomura, Susann Muller, Andreas Krell, Takenobu Toyota, Hiroshi Hattori
ANNALS OF GLACIOLOGY, 56, 69, 1, 8, 2015年, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Effects of sea-ice growth and decay processes on the biogeochemical cycles in the polar oceans
Nomura D
Umi no Kenkyu (Oceanography in Japan), In Japanese with English abstract and figures, 24, 2, 2015., 24, 2, 51, 61, 日本海洋学会, 2015年, ［査読有り］, ［筆頭著者, 責任著者］
日本語, 海氷の生成と融解に伴う物理場の変化が極域海洋の物質循環過程に与える影響を把握するため,室内実験,フィールド観測を実施した。従来,海氷は,海洋表面を覆い,大気-海洋間の物質循環を妨げる"障壁"として認識されてきた。しかし,海氷は,気候変動に関わる温室効果ガスや揮発性有機化合物等の大気-海洋間の交換に重要な役割を果たしていることが分かってきた。本稿では,著者の研究グループが,これまで実施してきた海氷の生成と融解が極域海洋の物質循環に与える影響に関する研究を紹介する。In order to understand effects of sea-ice growth and decay processes on the biogeochemical cycles in the polar oceans, field observations in the Arctic, Antarctic, and Sea of Okhotsk as well as laboratory experiments were carried out. Sea-ice has not been considered in estimations of biogeochemical cycles, especially in gas exchange, in ice-covered seas because of the assumption that sea-ice acts as a barrier for atmosphere-ocean exchange. However, recent works have shown that sea ice and its snow cover play an active role in the exchange of gases between the ocean and atmosphere. In this paper, results obtained in my previous studies were reviewed. - Helicopter-borne observations with portable microwave radiometer in the Southern Ocean and the Sea of Okhotsk
Takeshi Tamura, Kay I. Ohshima, Jan L. Lieser, Takenobu Toyota, Kazutaka Tateyama, Daiki Nomura, Kazuki Nakata, Alexander D. Fraser, Peter W. Jansen, Kym B. Newbery, Robert A. Massom, Shuki Ushio
ANNALS OF GLACIOLOGY, 56, 69, 436, 444, 2015年, ［査読有り］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Variation of dimethylsulfide mixing ratio over the Southern Ocean from 36°S to 70°S
Koga S, Nomura D, Wada M
Polar Science, 8 (3), 306–313, 2014., 8, 3, 306, 313, 2014年09月, ［査読有り］
英語, 研究論文（学術雑誌） - 砕氷船を利用した海氷・海洋の生物地球化学研究
野村 大樹, 西岡 純, 川合 美千代, 大木 淳之, 田村 岳史
日本地球化学会年会要旨集, 61, 132, 132, 日本地球化学会, 2014年
日本語, 我が国におけるこれまでの海氷研究は、主に物理過程を明らかにすることに主眼が置かれ、海氷の物理的動態を実測や衛星観測、モデリングから明らかにする研究が精力的に進められてきた。一方で、海氷に関わる化学過程や生物過程に関しては、これまで十分な研究が展開されていなかった。海氷の生成が生み出す独特の海洋循環を介して、他海域の物質循環にまで多大な影響を与えているシステムの存在が指摘されており、これらのシステムを理解するためには、海氷の存在する時期から消失していくまでの詳細な時系列観測、ポリニヤにおける海氷の生成が起こっている現場での観測が欠かせない。また、地球規模で起こっている環境変動を理解するためには、通年観測する必要があり、海洋研究プラットフォームを生物地球化学分野で最大限活用すると同時に、厳冬期でも観測が続けられる本格的な観測研究用の砕氷船が欠かせないだろう。 - Winter-to-summer evolution of pCO(2) in surface water and air-sea CO2 flux in the seasonal ice zone of the Southern Ocean
D. Nomura, H. Yoshikawa-Inoue, S. Kobayashi, S. Nakaoka, K. Nakata, G. Hashida
BIOGEOSCIENCES, 11, 20, 5749, 5761, 2014年, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Arctic and Antarctic sea ice acts as a sink for atmospheric CO2 during periods of snowmelt and surface flooding
Daiki Nomura, Mats A. Granskog, Philipp Assmy, Daisuke Simizu, Gen Hashida
Journal of Geophysical Research: Oceans, 118, 12, 6511, 6524, American Geophysical Union (AGU), 2013年12月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］, ［国際誌］
研究論文（学術雑誌） - Characterization of ikaite (CaCO3·6H2O) crystals in first-year Arctic sea ice north of Svalbard
Daiki Nomura, Philipp Assmy, Gernot Nehrke, Mats A. Granskog, Michael Fischer, Gerhard S. Dieckmann, Agneta Fransson, Yubin Hu, Bernhard Schnetger
Annals of Glaciology, 54, 62, 125, 131, Cambridge University Press (CUP), 2013年, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］, ［国際誌］
研究論文（学術雑誌）,Abstract We identified ikaite crystals (CaCO3· 6H2O) and examined their shape and size distribution in first-year Arctic pack ice, overlying snow and slush layers during the spring melt onset north of Svalbard. Additional measurements of total alkalinity (TA) were made for melted snow and sea-ice samples. Ikaite crystals were mainly found in the bottom of the snowpack, in slush and the surface layers of the sea ice where the temperature was generally lower and salinity higher than in the ice below. Image analysis showed that ikaite crystals were characterized by a roughly elliptical shape and a maximum caliper diameter of 201.0±115.9 μm (n = 918). Since the ice-melting season had already started, ikaite crystals may already have begun to dissolve, which might explain the lack of a relationship between ikaite crystal size and sea-ice parameters (temperature, salinity, and thickness of snow and ice). Comparisons of salinity and TA profiles for melted ice samples suggest that the precipitation/dissolution of ikaite crystals occurred at the top of the sea ice and the bottom of the snowpack during ice formation/melting processes. - An artificial pool experiment in Antarctic sea ice: effects of sea ice melting on physical and biogeochemical components of pool water
Daiki Nomura, Daisuke Simizu, Suchana Chavanich, Hideo Shinagawa, Mitsuo Fukuchi
ANTARCTIC SCIENCE, 24, 5, 536, 544, 2012年10月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Direct measurements of DMS flux from Antarctic fast sea ice to the atmosphere by a chamber technique
Daiki Nomura, Seizi Koga, Nobue Kasamatsu, Hideo Shinagawa, Daisuke Simizu, Makoto Wada, Mitsuo Fukuchi
Journal of Geophysical Research: Oceans, 117, 4, Blackwell Publishing Ltd, 2012年, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Bromoform concentrations in slush-layer water in Antarctic fast ice
Daiki Nomura, Atsushi Ooki, Daisuke Simizu, Mitsuo Fukuchi
ANTARCTIC SCIENCE, 23, 6, 623, 628, 2011年12月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Incorporation of nitrogen compounds into sea ice from atmospheric deposition
Daiki Nomura, Andrew McMinn, Hiroshi Hattori, Shigeru Aoki, Mitsuo Fukuchi
MARINE CHEMISTRY, 127, 1-4, 90, 99, 2011年12月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - DMSP and DMS in coastal fast ice and under-ice water of Lützow-Holm Bay, eastern Antarctica
Nomura D, Kasamatsu N, Tateyama K, Kudoh S, Fukuchi M
Continental Shelf Research, 31, pp1377–1383, 2011., 31, 13, 1377, 1383, 2011年09月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Biogeochemical properties of water in surface ponds on Antarctic fast ice and their relationship with underlying sea-ice properties
Daiki Nomura, Daisuke Simizu, Hideo Shinagawa, Chinatsu Ouchida, Mitsuo Fukuchi
JOURNAL OF GLACIOLOGY, 57, 205, 848, 856, 2011年, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Flux of low salinity water from Aniva Bay (Sakhalin Island) to the southern Okhotsk Sea
Sachiko Oguma, Tsuneo Ono, Yutaka W. Watanabe, Hiromi Kasai, Shuichi Watanabe, Daiki Nomura, Humio Mitsudera
ESTUARINE COASTAL AND SHELF SCIENCE, 91, 1, 24, 32, 2011年01月, ［査読有り］
英語, 研究論文（学術雑誌） - Report on a portable laboratory, made from a modified cargo container, aboard the RV Shirase during the 2009-2010 Antarctic cruise of the 51st Japanese Antarctic Research Expedition (JARE-51)
Wada M, Koga S, Nomura D, Odate T, Fukuchi M
Antarctic Record, 55, 3, 269–286, 2011., 55, 3, 271, 278, 国立極地研究所, 2011年, ［査読有り］
日本語, 2009年に就航した新「しらせ」には,改造した20 ftコンテナを船上実験室として搭載するスペースが確保された.第51次日本南極地域観測隊では,このコンテナ実験室の内部に大気中の硫化ジメチル濃度を測定するためのプロトン移動反応質量分析計を収納し,観測を実施した.本稿では,コンテナ実験室の概要と今後改良すべき点等について報告する. - Rapid physically driven inversion of the air-sea ice CO2 flux in the seasonal landfast ice off Barrow, Alaska after onset of surface melt
Daiki Nomura, Hajo Eicken, Rolf Gradinger, Kunio Shirasawa
CONTINENTAL SHELF RESEARCH, 30, 19, 1998, 2004, 2010年11月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Nutrient distributions associated with snow and sediment-laden layers in sea ice of the southern Sea of Okhotsk
Daiki Nomura, Jun Nishioka, Mats A. Granskog, Andreas Krell, Sumito Matoba, Takenobu Toyota, Hiroshi Hattori, Kunio Shirasawa
MARINE CHEMISTRY, 119, 1-4, 1, 8, 2010年04月, ［査読有り］, ［筆頭著者, 責任著者］, ［国際共著］, ［国際誌］
英語, 研究論文（学術雑誌） - Effects of snow, snowmelting and refreezing processes on air–sea-ice CO2 flux
Nomura D, Yoshikawa-Inoue H, Toyota T, Shirasawa K
Journal of Glaciology, 56, 196, pp262–270, 2010., 56, 196, 262, 270, 2010年, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - Biogeochemical Properties of Sea Ice
McMinn A, Gradinger R, Nomura D
Field Techniques for Sea Ice Research, pp259–282, 2009., 2009年, ［国際共著］
研究論文（その他学術会議資料等） - Transport of chemical components in sea ice and under-ice water during melting in the seasonally ice-covered Saroma-ko Lagoon, Hokkaido, Japan
Daiki Nomura, Toru Takatsuka, Masao Ishikawa, Toshiyuki Kawamura, Kunio Shirasawa, Hisayuki Yoshikawa-Inoue
ESTUARINE COASTAL AND SHELF SCIENCE, 81, 2, 201, 209, 2009年01月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌） - The effect of sea-ice growth on air-sea CO2 flux in a tank experiment
Daiki Nomura, Hisayuki Yoshikawa-Inoue, Takenobu Toyota
TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY, 58, 5, 418, 426, 2006年11月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）
その他活動・業績
- 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, 2024年08月, ［査読有り］
東京 : 水産海洋学会, 日本語 - ADCP velocity data during leg 5 of MOSAiC expedition with R/V Polarstern
Kawaguchi, Y, Z. Koenig, D. Nomura, M. Hoppman, Discover and access Arctic and Antarctic Data (ADS), 2022年08月
その他 - 北極海,多年氷下境界層の物理過程に関する研究(MOSAiC観測の報告)
川口悠介, KOEING Zoe, KOEING Zoe, 野村大樹, HOPPMAN Mario, 猪上淳, RABE Ben, SCHULZ Kristin, FANG Ying-Chih, KATLEIN Christian, NICOLAUS Marcel, 日本海洋学会大会講演要旨集, 2021, 2021年 - 有色溶存有機物(CDOM)から見る西部北太平洋及び北部ベーリング海の水塊構造と栄養塩分布
大井田穣示, 平譯享, 山下洋平, 阿部泰人, 西岡純, 和賀久朋, 野村大樹, 日本地球惑星科学連合大会予稿集(Web), 2020, 2020年 - 有色溶存有機物(CDOM)の光学的特性から見る西部北太平洋及び北部ベーリング海の水塊構造と栄養塩分布
大井田穣示, 平譯享, 平譯享, 山下洋平, 阿部泰人, 西岡純, 西岡純, 和賀久朋, 和賀久朋, 野村大樹, 野村大樹, 日本海洋学会大会講演要旨集, 2020, 2020年 - アナディール湾における水塊の経年変動:Dense Shelf Waterと太平洋起源水の影響
阿部泰人, 野村大樹, 野村大樹, 野村大樹, 平譯享, 平譯享, 日本海洋学会大会講演要旨集, 2020, 2020年 - 酸素安定同位体比を用いたベーリング海北部アナディール湾における高密度陸棚水形成の評価
野村大樹, 野村大樹, 野村大樹, 阿部泰人, 平譯享, 平譯享, 大木淳之, 大木淳之, 山下洋平, 村山愛子, 小野数也, 西岡純, 西岡純, 日本海洋学会大会講演要旨集, 2020, 2020年 - ロシア船を用いた西部ベーリング海の観測研究-航海の概要-
西岡純, 西岡純, 安田一郎, 平譯享, 平譯享, 小野数也, 村山愛子, 山下洋平, 李勃豊, 森雄太郎, 野村大樹, 野村大樹, 阿部泰人, 和賀久朋, 和賀久朋, 和賀久朋, 田副博文, 藤尾伸三, 柳本大吾, 川口悠介, 李根淙, 木村詩乃, 宋智暎, 島崎智広, 野口真希, 林央之, 宗林留美, 近藤拓斗, 三好友子, 三好友子, 岡崎裕典, CHEUNG Shun Yan, LIU Kailin, SCHERBININ A., LIU Hongbin, 近藤能子, 角皆潤, 長尾誠也, 井上睦夫, 原田尚美, 小川浩史, 小畑元, 乙坂重嘉, 乙坂重嘉, 鈴木崇史, 鈴木光次, 渡辺豊, 亀山宗彦, 関宰, 深町康, 江淵直人, 大島慶一郎, 大島慶一郎, 三寺史夫, 若土正暁, VOLKOV Y. N., 日本海洋学会大会講演要旨集, 2020, 2020年 - サロマ湖における海氷の波長別アルベドと透過率測定
谷川朋範, Pat Wongpan, 豊田威信, 平譯享, 野村大樹, 中山雅茂, 直木和弘, 庭野匡思, 堀雅裕, 青木輝夫, 青木輝夫, 雪氷研究大会講演要旨集(Web), 2019, 2019年 - 海氷変動を軸とした両極の環境変動の解明
田村岳史, 溝端浩平, 渡邉英嗣, 三瓶真, 山本正伸, 野村大樹, 西岡純, 渡邉豊, 末吉哲雄, 日本地球惑星科学連合大会予稿集(Web), 2017, 2017年 - 海氷変動を軸とした両極の環境変動の解明
田村岳史, 溝端浩平, 渡邉英嗣, 三瓶真, 山本正伸, 野村大樹, 西岡純, 渡邉豊, 極域科学シンポジウム(Web), 7th, 2016年 - 海氷変動を軸とした両極の環境変動の解明
田村岳史, 溝端浩平, 渡邉英嗣, 三瓶真, 山本正伸, 野村大樹, 西岡純, 渡邉豊, 日本地球惑星科学連合大会予稿集(Web), 2016, 2016年 - Biogeochemical data of the 51st Japanese Antarctic Research Expedition in the austral summer of 2009-2010
Nomura Daiki, Simizu Daisuke, Oouchida Chinatsu, Yasui Saori, Iida Takahiro, Hashida Gen, Fukuchi Mitsuo, JARE data reports. Marine biology, 41, 1, 13, 2011年09月
国立極地研究所, 英語 - 海氷表面から大気への硫化ジメチルの放出について
野村大樹, 古賀聖治, 笠松伸江, 品川秀夫, 清水大輔, 和田誠, 小達恒夫, 福地光男, 雪氷研究大会講演要旨集, 2010, 2010年 - 海氷表面から大気への硫化ジメチルの放出について
野村大樹, 古賀聖治, 笠松伸江, 品川秀夫, 清水大輔, 和田誠, 小達恒夫, 福地光男, 日本海洋学会大会講演要旨集, 2010, 2010年 - 南極昭和基地沖における海氷中の硫化ジメチルとその前駆体の鉛直分布
野村大樹, 笠松伸江, 舘山一孝, 飯田高大, 工藤栄, 小達恒夫, 福地光男, 日本海洋学会大会講演要旨集, 2009, 2009年
共同研究・競争的資金等の研究課題
- 南大洋の海氷中アンモニアおよび酸化態窒素供給源の推定
一般共同研究
2025年04月 - 2026年03月
高橋啓伍, 野村大樹, 黒沢則夫
国立極地研究所, G7-06 - 東南極における氷床－海氷－海洋システムの地域特性の解明 研究代表者 田村岳史 研究期間 (年度) 2021–2026 研究種目 基盤研究(A)
科学研究費助成事業
2021年 - 2026年03月
田村 岳史, 草原 和弥, 溝端 浩平, 平野 大輔, 野村 大樹, 巻 俊宏, 渡辺 豊
白瀬氷河底面融解量と外洋からの熱供給との比較
白瀬氷河が存在するリュツォ・ホルム湾で取得した海洋観測データの解析から明らかにした白瀬氷河―海洋相互作用に関する研究結果を、海洋―海氷―棚氷結合モデルによる実験結果と比較・統合し、顕著な季節変動を伴う年間を通じた白瀬氷河舌の底面融解プロセスを明らかにした。海洋―海氷―棚氷結合モデルによる実験結果からは、中層での海流の変動が、沖合の暖水のLH湾湾内への流入の変動の決め手となっている事が示唆された。さらにこの数値モデルの結果からは、LH湾で卓越する存在である沿岸定着氷の存在が、大気海洋間の熱交換を遮断して海氷生成を抑制し、これが沖合から白瀬氷河への暖水流入をより強くする（又は暖かいままにしてたどり着く）要因を作っている事が明らかになった。衛星観測、海洋観測、測地観測、数値モデル結果は全て、白瀬氷河の高い底面融解率を示している。
ケープダンレー周辺域での海氷生産と外洋からの熱供給との比較
ケープダンレー周辺域において、顕著な海氷後退が海面での熱貯留を増やし、東風によりアメリ―棚氷下へ押し込まれると同時に棚氷底面を融解させて、ケープダンレー沖の暖水化・淡水化をもたらす一連の過程が現場観測により捉えられた。このケープダンレーからの底層水流出を数値実験で再現するうえで、観測に基づく詳細な現実地形を考慮することが、流出量の絶対値に大きく影響することが明らかになった。
このように、交付申請書に記載した「研究の目的」及び「研究実施計画」について、上記のように直接的に研究目的に対して成果を上げる事となった。
日本学術振興会, 基盤研究(A), 国立極地研究所, 21H04931 - 氷河がフィヨルド環境に果たす役割 ―グリーンランドとパタゴニアで何が違うのか―
2024年04月 - 2025年03月
野村大樹, 杉山慎, 漢那直也, 松野孝平, 干場康博
北海道大学低温科学研究所, 一般共同研究, 北海道大学低温科学研究所, 24G046 - 海氷表面に見られる有機臭素ガスの高濃度現象―低温化学反応チャンバー実験による検証 研究代表者 野村大樹 研究期間 (年度) 2020 – 2022 研究種目 基盤研究(B)
科学研究費助成事業
2020年 - 2023年03月
野村 大樹, 薮下 彰啓, 山下 洋平, 大木 淳之
高緯度海域に分布する海氷は、地球規模の気候変動を制御する要因として大きな役割を担っている。従来、海氷は、物質循環の観点において大気と海洋間の「障壁」として認識されてきた。しかし、実際、海氷表面では、結氷による濃縮効果によって溶存物質が高濃度化し、大気に対して放出源になることが予想される。ただ、極域の厳しい環境での観測の難しさにより、海氷表面での「低温化学」に関する反応機構の解明に至っていない。本研究では、自然界で起こる結氷現象を室内でのチャンバー実験で再現し、有機臭素ガス、特にブロモホルムに関して、海氷表面での化学反応機構・大気への放出過程を明らかにすることが目的である。本課題は、極域大気中オゾン濃度の急激な減少を招く有機臭素ガスの発生源が特定されていないことから設定した。本研究で提唱する海氷表面でのブロモホルム生成は、有機臭素ガスの大気への新たな発生源の提案となり、長年謎とされてきた大気中オゾン消失現象の原因解明に一石を投じることとなる。しかし、これまでの応募者らによる観測事実と低温環境での化学反応の新たな知見により、反応仮説を提唱するに至ったが、反応機構は検証されていない。そこで本年度は、チャンバー実験を実施し、本研究の解明に向けてのデータの採取を行った。具体的には、購入したチャンバーを利用した化学反応実験、また、室内での結氷および積雪を再現し、ブロモホルム生成に関する室内実験を実施した。また、これまでの観測データの解析を実施した。これらの解析を実施することにより、当初の目的に向けて順調に研究が進んでいる状況にある。
日本学術振興会, 基盤研究(B), 北海道大学, 20H04345 - イメージングとAIで紐解く南大洋の炭素循環 研究代表者 真壁竜介 研究期間（年度）2023-2028 研究種目 CREST
2023年 - 海氷-海洋境界層理論に基づく海氷モニタリング技術開発と自動観測ネットワークの構築 研究代表者 川口悠介 研究期間 (年度) 2022-2025 研究種目 基盤研究(B)
2022年 - 海の暗い所で珪藻が栄養塩を消費する事実－生存戦略の仮説を提唱－研究代表者 大木淳之 研究期間 (年度) 2021–2025 研究種目 挑戦的研究（萌芽）
2022年 - 日独共同観測による「北極の湿潤化」の追究 研究代表者 猪上 淳 研究期間 (年度) 2018 – 2020 研究種目 国際共同研究加速基金(国際共同研究強化(B))
2018年
競争的資金 - 海洋炭酸系物質の時空間高解像度マッピング技術の南大洋への展開 研究代表者 渡辺 豊 研究期間 (年度) 2018 – 2020 研究種目 基盤研究(A)
2018年
競争的資金 - 北極漂流横断観測による「新しい北極海」の探究 研究代表者 猪上 淳 研究期間 (年度) 2018 – 2021 研究種目 基盤研究(A)
2018年
競争的資金 - 極域雪氷の融解現象が海洋表層の二酸化炭素濃度と大気との気体交換過程に与える影響 研究代表者 野村 大樹 研究期間 (年度) 2017 – 2019 研究種目 若手研究(A)
2017年
競争的資金 - 海洋沿岸におけるヨウ素循環の解明－有機物分解に伴うヨウ素の化学形態変化－ 研究代表者 大木 淳之 研究期間 (年度) 2016 – 2020 研究種目 基盤研究(B)
2016年
競争的資金 - 氷上現場観測による冬季海氷域の大気－海氷－海洋間の炭素輸送プロセスの解明
科学研究費助成事業
2012年04月 - 2015年03月
野村 大樹
本研究の目的は、冬季海氷域の大気－海氷－海洋間の炭素および物質輸送プロセスを明らかにすることである。これまでの調査では、気候条件の厳しさやプラットフォームの整備が課題となり、冬季の氷上野外観測は実現困難であった。そこで本研究では、冬季の観測を集中的に実施した。特に今年度は、
(1) アルフレッドウェゲナー極地海洋研究所（ドイツ）が所有する砕氷船ポーラシュテルンを用いた厳冬期南極海（2013年6-8月）で採取したサンプルの分析作業を実施した。分析結果を組み合わせ、大気―海氷間の二酸化炭素とブロモホルム交換量の評価／変動要因を明らかにした。上記分析で得られた結果をまとめ、国際学会および国内学会で成果発表した。現在、国際査読誌への投稿に向けて執筆作業を進めている。
(2) ノルウェー極地研究所（ノルウェー）が所有する砕氷船ランセを用いた厳冬期北極海航海（2015年2-3月）に参加し、氷上観測を実施した。観測サイトでは、海氷上積雪、海氷、海氷下海水を採取した。また、大気―海氷間の二酸化炭素とブロモホルム交換量の測定を実施した。特に、大気―海氷間の二酸化炭素交換量の測定では、気温による交換量の変化、積雪による交換量の抑制に関する貴重なデータを取得した。今後、各研究機関での分析、データ解析をする。そして、分析結果、取得データ解析をまとめ、国際学会および国内学会で成果発表する。最終的に（１）（２）を組み合わせ、冬季海氷域の大気－海氷－海洋間の炭素および物質輸送プロセスを明らかにする。
日本学術振興会, 特別研究員奨励費, 北海道大学, 12J04175 - 海洋の炭酸系物質の準リアルタイムな時空間高解像度マッピングの展開に関する研究 研究代表者 渡辺 豊 研究期間 (年度) 2015 – 2017 研究種目 基盤研究(B)
2015年
競争的資金 - 海氷内部における炭酸カルシウム結晶の生成メカニズムの解明 研究代表者 野村 大樹 研究期間 (年度) 2015 – 2016 研究種目 若手研究(B)
2015年
競争的資金 - 海氷融解による生態系の変化が物質循環に与える影響ー豪州砕氷船による国際南極観測ー 研究代表者 飯田 高大 研究期間 (年度) 2015 – 2017 研究種目 基盤研究(B)
2015年
競争的資金 - 南極海における海氷の生成と融解が大気-海洋間の二酸化炭素交換過程に及ぼす影響 研究代表者 野村 大樹 研究期間 (年度) 2009 – 2010 研究種目 研究活動スタート支援
科学研究費助成事業
2009年 - 2010年
野村 大樹
南極海における海氷の生成と融解が大気-海洋間の二酸化炭素(CO_2)交換過程に及ぼす影響を定量的に評価するため、2009年11月から2010年3月に砕氷艦『新しらせ』を用い、南極海季節海氷域で海氷/海洋観測を実施した。本観測データは、厳しい気候条件により、殆ど観測例がない南極海の海氷域の炭素循環についての有益なデータを提示する事が可能となった。本研究で得られた結果は、南極海の物質循環に関する将来予測研究の進展に大きく貢献できると考えられる。
日本学術振興会, 研究活動スタート支援, 国立極地研究所, 競争的資金, 21810036 - 海氷生成と融解に伴う大気への二酸化炭素放出・吸収に関する研究
科学研究費助成事業
2007年 - 2008年
野村 大樹
『研究の目的』は、季節海氷域での氷上現場観測より海氷の生成・融解に伴う大気-海洋間のCO_2交換を支配する要因を明らかにし、季節海氷域が炭素循環に果たす役割を評価することである。本年度の『研究実施計画』は、平成19年度に実施した観測・分析(1、季節海氷域での大気-海氷間の各種気体交換量の解明、2、海氷中ブライン・海氷下海水のサンプリング及び各種気体の分析)の結果をまとめ、学会発表、国際雑誌に投稿することである。以下に本年度に国際雑誌に投稿済み(2報)、受理済み(1報)の論文の内容を示す。
1.季節海氷域での大気-海氷間の各種気体交換量の解明(国際雑誌投稿中)
2006、2008年2-3月にオホーツク沿岸サロマ湖で大気-海氷間のCO_2フラックスを測定した。大気-海氷間のCO_2フラックスは、-2.3から+0.5mg-Cm^<-2>hour^<-1>となった。観測期間中、積雪及び海水表面の融解と再凍結によって出来た氷に海氷表面が覆われる時期があった。その結果、ブライン・チャネルのような気体交換を可能とする場所が、海氷表面での融解と再凍結によって塞がれたため、大気から海氷へのCO_2吸収が制限された。大気-海氷中ブライン間のpCO_2差にだけでなく、海氷表面の特性も、大気-海氷間のCO_2フラックスを決定する重要な要因であることが示された。
2.海氷中ブライン・海氷下海水のサンプリング及び各種気体の分析(国際雑誌受理済)
海氷融解期におけるブライン・海氷下海水の化学特性変化を解明するため、2006、2008年2月-3月はじめにオホーツク海沿岸サロマ湖東部で氷上現場観測を行った。日中の気温の上昇に伴い、海氷上部または内部での融解や、河川水流入量増加によりブライン・表層水の塩分は大幅に減少した。中層・深層では、ほぼ一定の値となった。DO、TA、栄養塩各種は、塩分と同様にブライン・表層水で大きく変化した。観測点がサロマベツ川に近づくほど、その値は河川のものと近くなった。これは、主に河川水量増加によってSt.Main表層水の値が変化したことを示唆している。また、海氷から融解水が海氷下に流出する際、入れ替わりに海氷直下の海水をブライン・チャネル内に取り込むためにブラインの各成分値も大きく変化した。
日本学術振興会, 特別研究員奨励費, 北海道大学, 07J05968
