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11 results on '"Takeyoshi Nagai"'

1. Elevated turbulent and double-diffusive nutrient flux in the Kuroshio over the Izu Ridge and in the Kuroshio Extension

Author

Fuminori Hashihama, Takeyoshi Nagai, Gandy Maria Rosales Quintana, Gloria Silvana Durán Gómez, and Kosei Komatsu

Subjects
沖縄トラフ・トカラ海峡で高鉛直波数近慣性波シアと乱流が卓越するメカニズム, The Kuroshio Extension, 010504 meteorology & atmospheric sciences, Resolving multi-scale mixing processes and their impacts using a twin tow-yo microstructure profiling system, Nitrate flux, Geometry, Nutrient flux, Oceanography, 01 natural sciences, Mechanisms of dominant vertical high wavenumber near inertial shear and strong turbulence in the Okinawa Trough and the Tokara Strait, Near-inertial wave generations and diapycnal mixing in the Kuroshio origin regions near the continental shelf, Double-Diffusion, 0105 earth and related environmental sciences, Physics, 二台同時自由落下曳航観測手法を用いたマルチスケール混合現象とその影響に関する研究, The Kuroshio, 010505 oceanography, Turbulence, Double diffusion, Izu-Ridge, 科学研究費研究成果, 黒潮源流が陸棚縁で生成する近慣性内部波と躍層における鉛直混合メカニズムの解明, Ridge (meteorology), Diffusive flux, Production (computer science)
Abstract

While the Kuroshio is known to be a nutrient stream, as these nutrients are in dark subsurface layers, they are not immediately available for photosynthesis unless they are supplied to the sunlit surface layers. Recent microstructure observations have revealed that strong diapycnal mixing caused by the Kuroshio flowing over topographic features and double diffusion in the subsurface layers of the Kuroshio. However, it is still unclear how much nutrient flux can be provided by these microscale mixing processes. In this study, using an autonomous microstructure float and nutrient samplings, nutrient flux caused by the Kuroshio over the Izu Ridge, and that caused by double diffusion in the Kuroshio Extension are quantified. The nitrate diffusive flux is estimated to be $$>1 \,\hbox {mmol} \,\hbox {N}\,\hbox {m}^{-2}\hbox {day}^{-1}$$ > 1 mmol N m - 2 day - 1 over a distance, 20–30 km near the Izu Ridge and $$>0.1 \,\hbox {mmol} \,\hbox {N}\, \hbox {m}^{-2}\hbox {day}^{-1}$$ > 0.1 mmol N m - 2 day - 1 , which persists further downstream direction over 100 km along the Kuroshio, increasing the subsurface chlorophyll-a concentration in the region 200 km downstream. The double-diffusion-induced nitrate flux is estimated to be 1-$$10 \,\hbox {mmol} \,\hbox {N} \,\hbox {m}^{-2}\hbox {day}^{-1}$$ 10 mmol N m - 2 day - 1 in the pycnostad 26–$$26.5\,\hbox {kgm}^{-3}$$ 26.5 kgm - 3 of the Kuroshio Extension, suggesting that whether this double-diffusion-induced nutrient flux in the subsurface layers can ultimately contribute to surface primary production depends on additional eddy up- and northward fluxes.

Published
2021

2. Phytoplankton growth and consumption by microzooplankton stimulated by turbulent nitrate flux suggest rapid trophic transfer in the oligotrophic Kuroshio

Author

Eisuke Tsutsumi, Gen Kume, Taiga Honma, Takeyoshi Nagai, Toru Kobari, Fukutaro Karu, Takahiro Tanaka, Naoki Yoshie, Xinyu Guo, Koji Suzuki, Ayako Nishina, Takeru Kanayama, Daisuke Hasegawa, Hirohiko Nakamura, and Takeshi Matsuno

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, fungi, lcsh:QE1-996.5, Foraging, lcsh:Life, Plankton, 01 natural sciences, lcsh:Geology, lcsh:QH501-531, Oceanography, Nutrient, Productivity (ecology), Eddy, lcsh:QH540-549.5, Phytoplankton, Environmental science, Photic zone, lcsh:Ecology, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Earth-Surface Processes, Trophic level
Abstract

The Kuroshio Current has been thought to be biologically unproductive because of its oligotrophic conditions and low plankton standing stocks. Even though vulnerable life stages of major foraging fishes risk being entrapped by frontal eddies and meanders and encountering low food availability, they have life cycle strategies that include growing and recruiting around the Kuroshio Current. Here we report that phytoplankton growth and consumption by microzooplankton are stimulated by turbulent nitrate flux amplified by the Kuroshio Current. Oceanographic observations demonstrate that the Kuroshio Current topographically enhances significant turbulent mixing and nitrate influx to the euphotic zone. Graduated nutrient enrichment experiments show that growth rates of phytoplankton and microheterotroph communities were stimulated within the range of the turbulent nitrate flux. Results of dilution experiments imply significant microzooplankton grazing on phytoplankton. We propose that these rapid and systematic trophodynamics enhance biological productivity in the Kuroshio.

Published
2020

3. Mesoscale Warm-Core Eddies Drive Interannual Modulations of Swordfish Catch in the Kuroshio Extension System

Author

Kotaro Yokawa, Gloria Silvana Durán Gómez, and Takeyoshi Nagai

Subjects
0106 biological sciences, Biogeochemical cycle, eddy detection technique, 010504 meteorology & atmospheric sciences, lcsh:QH1-199.5, Mesoscale meteorology, interannual modulation, Ocean Engineering, Aquatic Science, lcsh:General. Including nature conservation, geographical distribution, Oceanography, 01 natural sciences, Mesoscale eddies, Modulation (music), lcsh:Science, Basin scale, 0105 earth and related environmental sciences, Water Science and Technology, Global and Planetary Change, 010604 marine biology & hydrobiology, Swordfish, mesoscale eddies, Eddy, Anticyclone, Kuroshio Extension decadal modulation, swordfish fishery, CPUE, lcsh:Q, Geology
Abstract

Recent observational and numerical studies have suggested that the decadal modulation of the Kuroshio Extension system, driven by mesoscale variabilities, profoundly affect the basin scale physical and biogeochemical oceanography. However, it remains unclear how these decadal changes affect distribution and abundance of fish species in this region. In this study, 26,964 swordfish catch data obtained by longliners during 2004 and 2010 in the western North Pacific are analyzed with an eddy-resolving ocean reanalysis by using mesoscale dynamic parameters and an eddy detection technique, to clarify the effects of mesoscale eddies and their variabilities on the swordfish catch and distribution. During this period, the Kuroshio Extension underwent two different dynamic phases: stable path state in 2004, 2005 and 2010; and unstable path state during 2006-2009. Based on our analyses, we show here that swordfish are more concentrated in and near the anticyclonic warm-core eddies in the northern site, 36 -45 • N, of the Kuroshio Extension system, especially during the unstable path phase. This is found to be caused by the interannual modulation of mesoscale eddy activities due to more warm-core rings generated from the unstable Kuroshio Extension, making it easier for fishermen to target swordfish in this region.

Published
2020

4. Nutrient interleaving below the mixed layer of the Kuroshio Extension Front

Author

Takeyoshi Nagai and Sophie Clayton

Subjects
Turbulent diffusion, 010504 meteorology & atmospheric sciences, Interleaving, 010505 oceanography, Turbulence, Mixed layer, Oceanography, Atmospheric sciences, 01 natural sciences, Gulf Stream, chemistry.chemical_compound, Frontogenesis, Nitrate, chemistry, Geostrophic wind, Geology, 0105 earth and related environmental sciences
Abstract

Nitrate interleaving structures were observed below the mixed layer during a cruise to the Kuroshio Extension in October 2009. In this paper, we investigate the formation mechanisms for these vertical nitrate anomalies, which may be an important source of nitrate to the oligotrphoc surface waters south of the Kuroshio Extension Front. We found that nitrate concentrations below the main stream of the Kuroshio Extension were elevated compared to the ambient water of the same density (σ 𝜃 = 23.5–25). This appears to be analogous to the “nutrient stream” below the mixed layer, associated with the Gulf Stream. Strong turbulence was observed above the vertical nitrate anomaly, and we found that this can drive a large vertical turbulent nitrate flux $>\mathcal {O}$ (1 mmol N m−2 day−1). A realistic, high-resolution (2 km) numerical simulation reproduces the observed Kuroshio nutrient stream and nitrate interleaving structures, with similar lateral and vertical scales. The model results suggest that the nitrate interleaving structures are first generated at the western side of the meander crest on the south side of the Kuroshio Extension, where the southern tip of the mixed layer front is under frontogenesis. Lagrangian analyses reveal that the vertical shear of geostrophic and subinertial ageostrophic flow below the mixed layer tilts the existing along-isopycnal nitrate gradient of the Kuroshio nutrient stream to form nitrate interleaving structures. This study suggests that the multi-scale combination of (i) the lateral stirring of the Kuroshio nutrient stream by developed mixed layer fronts during fall to winter, (ii) the associated tilting of along-isopycnal nitrate gradient of the nutrient stream by subinertial shear, which forms vertical interleaving structures, and (iii) the strong turbulent diffusion above them, may provide a route to supply nutrients to oligotrophic surface waters on the south side of the Kuroshio Extension.

Published
2017

5. Measurement of sardine-generated turbulence in a large tank

Author

Tomonari Okada, Mamoru Tanaka, Hidekatsu Yamazaki, and Takeyoshi Nagai

Subjects
0106 biological sciences, Turbulent mixing, 010504 meteorology & atmospheric sciences, Ecology, Sardinops melanostictus, Turbulence, 010604 marine biology & hydrobiology, Sardine, Aquatic Science, 01 natural sciences, Fishery, Oceanography, Environmental science, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences
Published
2017

6. Phytoplankton productivity and rapid trophic transfer to microzooplankton stimulated by turbulent nitrate flux in oligotrophic Kuroshio Current

Author

Eisuke Tsutumi, Naoki Yoshie, Hirohiko Nakamura, Takeshi Matsuno, Daisuke Hasegawa, Xinyu Guo, Ayako Nishina, Takeru Kanayama, Takahiro Tanaka, Takeyoshi Nagai, Fukutaro Karu, Toru Kobari, Koji Suzuki, Gen Kume, and Taiga Honma

Subjects
Oceanography, 010504 meteorology & atmospheric sciences, Productivity (ecology), Eddy, Advection, Phytoplankton, Front (oceanography), Environmental science, Photic zone, Plankton, 01 natural sciences, 0105 earth and related environmental sciences, Trophic level
Abstract

The Kuroshio Current has been thought to be biologically unproductive due to oligotrophic conditions and low plankton standing stocks. Nevertheless, major foraging fishes are known to grow and recruit around the Kuroshio Current. While mixing and advection supplying nutrients to the euphotic zone are happened by eddies and meanders but limited at the Kuroshio front, there is a risk that survival of vulnerable life stages is encountered under the low food availability. Here we report that phytoplankton productivity is stimulated by turbulent nitrate flux amplified with the Kuroshio Current and rapidly transferred to microzooplankton through their grazing. Oceanographic observations demonstrate that the Kuroshio Current topographically enhances significant turbulent mixing and nitrate influx to the euphotic zone. Gradual nutrient enrichment experiments show growth rates of phytoplankton and microzooplankton communities stimulated within a range of the turbulent nitrate flux. Dilution experiments imply a significant microzooplankton grazing on phytoplankton. We propose that these rapid and systematic trophodynamics enhance invisible biological productivity in the Kuroshio.

Published
2019

7. Global Perspectives on Observing Ocean Boundary Current Systems

Author

Robert E. Todd, Francisco P. Chavez, Sophie Clayton, Sophie Cravatte, Marlos Goes, Michelle Graco, Xiaopei Lin, Janet Sprintall, Nathalie V. Zilberman, Matthew Archer, Javier Arístegui, Magdalena Balmaseda, John M. Bane, Molly O. Baringer, John A. Barth, Lisa M. Beal, Peter Brandt, Paulo H. R. Calil, Edmo Campos, Luca R. Centurioni, Maria Paz Chidichimo, Mauro Cirano, Meghan F. Cronin, Enrique N. Curchitser, Russ E. Davis, Marcus Dengler, Brad deYoung, Shenfu Dong, Ruben Escribano, Andrea J. Fassbender, Sarah E. Fawcett, Ming Feng, Gustavo J. Goni, Alison R. Gray, Dimitri Gutiérrez, Dave Hebert, Rebecca Hummels, Shin-ichi Ito, Marjorlaine Krug, François Lacan, Lucas Laurindo, Alban Lazar, Craig M. Lee, Matthieu Lengaigne, Naomi M. Levine, John Middleton, Ivonne Montes, Mike Muglia, Takeyoshi Nagai, Hilary I. Palevsky, Jaime B. Palter, Helen E. Phillips, Alberto Piola, Albert J. Plueddemann, Bo Qiu, Regina R. Rodrigues, Moninya Roughan, Daniel L. Rudnick, Ryan R. Rykaczewski, Martin Saraceno, Harvey Seim, Alex Sen Gupta, Lynne Shannon, Bernadette M. Sloyan, Adrienne J. Sutton, LuAnne Thompson, Anja K. van der Plas, Denis Volkov, John Wilkin, Dongxiao Zhang, Linlin Zhang, Woods Hole Oceanographic Institution (WHOI), Monterey Bay Aquarium Research Institute (MBARI), Monterey Bay Aquarium Research Institute, Océan du Large et Variabilité Climatique (OLVAC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Instituto del Mar del Peru (IMARPE), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Fac. Ciencias del Mar, University of Las Palmas de Gran Canaria (ULPGC), European Centre for Medium-Range Weather Forecasts (ECMWF), Université Grenoble Alpes - Institut d'urbanisme et de géographie alpine (IUGA), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Coastal & Marine Research Centre, University College Cork (UCC), Institute of Marine and Coastal Sciences, Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), National Oceanic and Atmospheric Administration (NOAA), Millennium Institute of Oceanography, Universidad de Concepción [Chile], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Direccion de Investigaciones Oceanograficas, Océan et variabilité du climat (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), University of Southern California (USC), Departamento de Oceanografía [Concepción], Departamento de Oceanografia, Servicio de Hidrografía Naval, School of Ocean and Earth Science and Technology (SOEST), University of Hawai‘i [Mānoa] (UHM), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Climate Change Research Centre [Sydney] (CCRC), University of New South Wales [Sydney] (UNSW), Marine Research Institute and Department of Biological Sciences, University of Cape Town, CSIRO, Oceans and Atmosphere, Hobart, TAS, Australia, Rutgers University System (Rutgers), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), Universidad de Concepción - University of Concepcion [Chile], Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, lcsh:QH1-199.5, Computer science, Climate system, Ocean Engineering, Aquatic Science, lcsh:General. Including nature conservation, geographical distribution, drifters, Oceanography, 01 natural sciences, purl.org/becyt/ford/1 [https], purl.org/becyt/ford/1.5 [https], eastern boundary current systems, remote sensing, ocean observing systems, Global network, moorings, 14. Life underwater, western boundary current systems, lcsh:Science, ddc:3, 0105 earth and related environmental sciences, Water Science and Technology, Global Ocean Observing System, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, business.industry, 010604 marine biology & hydrobiology, Environmental resource management, Ocean current, article, autonomous underwater gliders, Boundary current, 13. Climate action, ddc:333.7, lcsh:Q, Current (fluid), time series, business
Abstract

Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations. Fil: Todd, Robert E.. Woods Hole Oceanographic Institution; Estados Unidos Fil: Chavez, Francisco. Monterey Bay Aquarium Research Institute; Estados Unidos Fil: Clayton, Sophie. Old Dominion University; Estados Unidos Fil: Cravatte, Sophie E.. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Francia. Universite de Toulouse; Francia Fil: Goes, Marlos P.. University of Miami; Estados Unidos Fil: Graco, Michelle I.. Instituto del Mar del Peru; Perú Fil: Lin, Xiaopei. Ocean University of China; China Fil: Sprintall, Janet. University of California; Estados Unidos Fil: Zilberman, Nathalie V.. University of California; Estados Unidos Fil: Archer, Matthew. California Institute of Technology; Estados Unidos Fil: Arístegui, Javier. Universidad de Las Palmas de Gran Canaria; España Fil: Balmaseda, Magdalena A.. European Centre for Medium-Range Weather Forecasts; Reino Unido Fil: Bane, John M.. University of North Carolina; Estados Unidos Fil: Baringer, Molly O.. Atlantic Oceanographic and Meteorological Laboratory ; Estados Unidos Fil: Barth, John A.. State University of Oregon; Estados Unidos Fil: Beal, Lisa M.. University of Miami; Estados Unidos Fil: Brandt, Peter. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania Fil: Calil, Paulo H.. Universidade Federal do Rio Grande; Brasil Fil: Campos, Edmo. Universidade de Sao Paulo; Brasil Fil: Centurioni, Luca R.. University of California; Estados Unidos Fil: Chidichimo, María Paz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina Fil: Cirano, Mauro. Universidade Federal do Rio de Janeiro; Brasil Fil: Cronin, Meghan F.. National Oceanic and Atmospheric Administration. Pacific Marine Environmental Laboratory; Estados Unidos Fil: Curchitser, Enrique N.. Rutgers University; Estados Unidos Fil: Davis, Russ E.. University of California; Estados Unidos Fil: Dengler, Marcus. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania Fil: DeYoung, Brad. Memorial University of Newfoundland; Canadá Fil: Dong, Shenfu. University of Miami; Estados Unidos Fil: Escribano, Ruben. Universidad de Concepción; Chile Fil: Fassbender, Andrea J.. Monterey Bay Aquarium Research Institute; Estados Unidos

Published
2019

8. On the Future of Argo: A Global, Full-Depth, Multi-Disciplinary Array

Author

Jonathan D. Nash, Andreas Sterl, Diarmuid Ó. Conchubhair, Mathieu Belbeoch, Toste Tanhua, Lynne D. Talley, Thierry Carval, Stephanie Waterman, Yueng-Djern Lenn, Kenneth S. Johnson, Ariel Troisi, Virginie Thierry, Sarah G. Purkey, Satya Prakash, Damien Desbruyères, Giorgio Dall'Olmo, Katja Fennel, Robert Hallberg, Gregory C. Johnson, James N. Moum, Ilker Fer, Brian A. King, Gael Forget, Emily L. Shroyer, Toshio Suga, Peter R. Oke, Rik Wanninkhof, Fei Chai, Are Olsen, Emmanuel Boss, Nicolas Kolodziejczyk, Markus Jochum, Sandy J. Thomalla, N. V. Zilberman, Amy F. Waterhouse, Guillaume Maze, Alberto C. Naveira Garabato, Catherine Schmechtig, Thomas W. Trull, Andrew J. Watson, Fabrizio D'Ortenzio, Haili Wang, Kjell Arne Mork, Pedro Vélez-Belchí, Paulo H. R. Calil, Philip Sutton, Jianping Xu, Steven R. Jayne, Tetsuichi Fujiki, Howard J. Freeland, Henry C. Bittig, Cara Wilson, Hervé Claustre, Ichiro Yasuda, Annie P. S. Wong, John M. Toole, Claudia Schmid, Megan Scanderbeg, Marion Gehlen, Raffaele Ferrari, Arne Körtzinger, Toshiyuki Hibiya, Dean Roemmich, Susan Wijffels, Tamaryn Morris, Sylvie Pouliquen, Matthew H. Alford, Takeyoshi Nagai, Waldemar Walczowski, Pierre-Yves Le Traon, Molly O. Baringer, Blair J. W. Greenan, W. Brechner Owens, KiRyong Kang, Jon Turton, Fiona Carse, Shigeki Hosoda, Rama Rao E. Pattabhi, Dorothee C. E. Bakker, Stephen C. Riser, Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Oceans and Atmosphere Flagship [Brisbane], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), University of California, CSIRO Marine and Atmospheric Research (CSIRO), University of East Anglia [Norwich] (UEA), School of Marine Sciences, University of Maine, Unité de recherche Géosciences Marines (Ifremer) (GM), Oregon State University (OSU), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Department of Oceanography [Halifax] (DO), Dalhousie University [Halifax], Bjerknes Centre for Climate Research (BCCR), Department of Biological Sciences [Bergen] (BIO / UiB), University of Bergen (UiB)-University of Bergen (UiB), Massachusetts Institute of Technology (MIT), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Cancer Genetics Branch, National Institute of Health (NIH)-National Human Genome Research Institute (NHGRI), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Biomedical Technology and Cell Therapy Research Laboratory, Montreal, Université Pierre et Marie Curie - Paris 6 (UPMC), Observatoire des sciences de l'univers Ecce Terra [Paris] (ECCE TERRA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Royal Netherlands Meteorological Institute (KNMI), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Southern Ocean Carbon and Climate Observatory, CSIR, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML), National Oceanic and Atmospheric Administration (NOAA), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Evolution Paris-Seine, Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Sorbonne Paris Cité (USPC), McMaster University [Hamilton, Ontario], University of California (UC), Géosciences Marines (GM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Observatoire des sciences de l'univers Ecce Terra [Paris] (OSU ECCE TERRA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Sorbonne Paris Cité (USPC)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), and Observatoire des sciences de l'univers Ecce Terra (ECCE TERRA)

Subjects
0106 biological sciences, lcsh:QH1-199.5, 010504 meteorology & atmospheric sciences, warming, Computer science, Data management, Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 [VDP], Sede Central IEO, Ocean Engineering, lcsh:General. Including nature conservation, geographical distribution, VDP::Oseanografi: 452, Aquatic Science, Oceanography, 01 natural sciences, salinity, Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 [VDP], Basic research, Multidisciplinary approach, Profiling (information science), 14. Life underwater, VDP::Oceanography: 452, lcsh:Science, Argo, 0105 earth and related environmental sciences, Water Science and Technology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Multi disciplinary, Oseanografi / Oceanography, business.industry, 010604 marine biology & hydrobiology, temperature, Ocean depth, floats, global, ocean, Sea surface temperature, 13. Climate action, Systems engineering, circulation, lcsh:Q, business, Oseanografi
Abstract

The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opportunistically from the combination of great scientific need and technological innovation. Through the data system, Argo provides fundamental physical observations with broad societally-valuable applications, built on the cost-efficient and robust technologies of autonomous profiling floats. Following recent advances in platform and sensor technologies, even greater opportunity exists now than 20 years ago to (i) improve Argo’s global coverage and value beyond the original design, (ii) extend Argo to span the full ocean depth, (iii) add biogeochemical sensors for improved understanding of oceanic cycles of carbon, nutrients, and ecosystems, and (iv) consider experimental sensors that might be included in the future, for example to document the spatial and temporal patterns of ocean mixing. For Core Argo and each of these enhancements, the past, present, and future progression along a path from experimental deployments to regional pilot arrays to global implementation is described. The objective is to create a fully global, top-to-bottom, dynamically complete, and multidisciplinary Argo Program that will integrate seamlessly with satellite and with other in situ elements of the Global Ocean Observing System (Legler et al., 2015). The integrated system will deliver operational reanalysis and forecasting capability, and assessment of the state and variability of the climate system with respect to physical, biogeochemical, and ecosystems parameters. It will enable basic research of unprecedented breadth and magnitude, and a wealth of ocean-education and outreach opportunities., Sí

Published
2019

9. Early-winter mixing event associated with baroclinic motions in weakly stratified Lake Biwa

Author

Hidekatsu Yamazaki, Takeyoshi Nagai, Hikaru Homma, and Kenji Shimizu

Subjects
0106 biological sciences, Convection, Shore, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, Baroclinity, Aquatic Science, Internal wave, Mooring, 01 natural sciences, symbols.namesake, Oceanography, Water column, Heat flux, symbols, Kelvin wave, Geology, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

The annual overturn of lake water (termed holomixis) during winter is essential in maintaining the environment of warm monomictic lakes by transporting heat and organic and inorganic constituents; however, direct observation of wintertime mixing processes is limited. To better understand the detailed physical processes responsible for holomixis, this study investigated a cold low-oxygen water intrusion event on the northeastern slope of weakly stratified Lake Biwa (Japan), observed using mooring systems. The intrusion occurred concurrently with superinertial oscillations of near-bottom currents. The effective Wedderburn number suggests that basin-scale Kelvin waves were excited by north¬eastward winds (~4 m s −1 ) prior to the intrusion event. The results of a modal analysis suggest that the intrusion was caused by a combination of Kelvin and Poincare waves that locally uplifted the cold deep water. The heat budget analyses revealed that a substantial part of the intruded cold water was mixed diapycnally, induced by wind stirring, nighttime convection, and bottom friction. The superinertial currents enhanced the dissipation due to bottom friction by ~30%. The cold water intrusion and subsequent mixing provided local heat flux of 98 W m −2 over 6 days, which was 1.4 times larger than the average surface heat flux over the same period. In addition to previously studied processes, such as surface cooling and gravity currents from the shore, this study indicates that wind-induced baroclinic motions and subsequent diapycnal mixing of a stratified water column contribute to holomixis.

Published
2016

10. First Evidence of Coherent Bands of Strong Turbulent Layers Associated with High-Wavenumber Internal-Wave Shear in the Upstream Kuroshio

Author

Takahiro Tanaka, Ryuichiro Inoue, Hirohiko Nakamura, Toru Yamashiro, Eisuke Tsutsumi, Daisuke Hasegawa, and Takeyoshi Nagai

Subjects
geography, Multidisciplinary, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010505 oceanography, Turbulence, Continental shelf, Internal tide, lcsh:R, lcsh:Medicine, Geophysics, Internal wave, 01 natural sciences, Article, Eddy diffusion, Physics::Fluid Dynamics, Turbulence kinetic energy, Physics::Space Physics, Wavenumber, lcsh:Q, lcsh:Science, Thermocline, Geology, 0105 earth and related environmental sciences
Abstract

The upstream Kuroshio flows through Okinawa Trough and the Tokara island chain, the region near the continental shelf of the East China Sea and shallow seamounts, where the Kuroshio can induce strong mixing over the shallow topography. Also, tidal currents over the rough topography may produce internal tides, and associated turbulence. The previous observations show energetic high vertical wavenumber near-inertial wave shear in the Kuroshio thermocline, which implies strong turbulent mixing. However, direct turbulence measurements in this region are very scarce. Using high lateral resolution (1–2 km) direct turbulence measurements, we show here, for the first time, that strong turbulent layers form spatially coherent banded structures with lateral scales of >O(10 km), associated with bands of near-inertial wave/diurnal internal tide shear of high vertical wavenumber in the upstream Kuroshio. The turbulent kinetic energy dissipation rates within these turbulent layers are >O(10−7 W kg−1), and estimated vertical eddy diffusivity shows >O(10−4 m2 s−1) on average. These results suggest that the high vertical wavenumber near-inertial waves propagating in the upstream Kuroshio could have large impacts on the watermass modifications, momentum mixing, nutrient supply, and associated biogeochemical responses in its downstream.

Published
2017

11. Eddy-induced reduction of biological production in eastern boundary upwelling systems

Author

Hartmut Frenzel, Nicolas Gruber, James C. McWilliams, Takeyoshi Nagai, Zouhair Lachkar, Gian-Kasper Plattner, Patrick Marchesiello, Matthias Münnich, Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), Institut Pierre-Simon-Laplace (IPSL), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), University of California-University of California, École normale supérieure - Paris (ENS Paris), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, fungi, Mesoscale meteorology, Primary production, Flux, Biogeochemistry, Pelagic zone, New production, 01 natural sciences, Oceanography, Eddy, 13. Climate action, General Earth and Planetary Sciences, Environmental science, Upwelling, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract

International audience; Eddies and other mesoscale oceanic processes, such as fronts, can enhance biological production in the ocean, according to several open-ocean studies. The effect is thought to be particularly pronounced in low-nutrient environments, where mesoscale processes increase the net upward flux of limiting nutrients. However, eddies have been suggested to suppress production in the highly productive eastern boundary upwelling systems. Here, we examine the relationship between satellite-derived estimates of net primary production, of upwelling strength, and of eddy-kinetic energy--a measure of the intensity of mesoscale activity--in the four most productive eastern boundary upwelling systems. We show that high levels of eddy activity tend to be associated with low levels of biological production, indicative of a suppressive effect. Simulations using eddy-resolving models of two of these upwelling systems support the suggestion that eddies suppress production, and show that the downward export of organic matter is also reduced. According to these simulations, the reduction in production and export results from an eddy-induced transport of nutrients from the nearshore environment to the open ocean. Eddies might have a similar effect on marine productivity in other oceanic systems that are characterized by intense eddy activity, such as the Southern Ocean.

Published
2011

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