Search

Your search keyword '"Taira Nagai"' showing total 6 results
Start Over Author "Taira Nagai" Language english
6 results on '"Taira Nagai"'

1. Revisiting Tide‐Induced Near‐Field Mixing in the Abyssal Ocean

Author

Toshiyuki Hibiya, Yuki Tanaka, Taira Nagai, and Yusuke Hirano

Subjects
near‐field mixing, internal lee waves, near‐inertial currents, rough seafloor topography, tidal excursion parameter, topographic steepness parameter, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract Vertical two‐dimensional numerical experiments incorporating Garrett‐Munk (GM) internal waves are conducted to investigate tide‐induced near‐field mixing over a finite‐amplitude sinusoidal seafloor, conventionally attributed to the breaking of high‐wavenumber internal tidal waves. Turbulent mixing is characterized by tidal excursion parameter (Te) and topographic steepness parameter (Sp) measuring tidal current strength and seafloor slope gradient, respectively. Under strong tidal currents (Te > 1), high‐wavenumber internal lee waves propagate upward from the seafloor. Even when Te and Sp are set to produce nearly the same upward energy flux, the vertical profile of mixing hotspots varies with Sp. For Sp ≳ 0.2, near‐inertial currents above the seafloor rapidly amplify by absorbing energy of internal lee waves from below, hindering their upward propagation and creating “short mixing hotspots.” For Sp

Published
2024
Full Text
View/download PDF

2. Historical CTD dataset and associated processed dissipation rate using an improved Thorpe method in the Indonesian seas

Author

Adi Purwandana, Yannis Cuypers, Pascale Bouruet-Aubertot, Taira Nagai, Toshiyuki Hibiya, and Agus S. Atmadipoera

Subjects
CTD dataset, Dissipation rate, Indonesian seas, Watermass, Vertical mixing, Turbulent mixing, Computer applications to medicine. Medical informatics, R858-859.7, Science (General), Q1-390
Abstract

In this article, we present the datasets which are used to estimate the turbulent kinetic energy dissipation rates and vertical diffusivity in the Indonesian seas. An archived CTD (conductivity, temperature, depth) datasets collected between 1990 and 2016 with 1 m vertical resolution is presented and analyzed using an improved Thorpe method. The direct estimates dataset of the dissipation rate from two research expeditions, i.e., INDOMIX Program in 2010 and TOMTOM Program in 2015 were also presented, available to be compared with the indirect estimates from CTD profiles. We also present the dissipation rate output of three recent regional internal tide models in the Indonesian seas for comparison with microstructure measurements and improved Thorpe estimates. The datasets refer to ''Spatial structure of turbulent mixing inferred from historical CTD datasets in the Indonesian seas'' [1].

Published
2020
Full Text
View/download PDF

3. Corrigendum: Detecting Change in the Indonesian Seas

Author

Janet Sprintall, Arnold L. Gordon, Susan E. Wijffels, Ming Feng, Shijian Hu, Ariane Koch-Larrouy, Helen Phillips, Dwiyoga Nugroho, Asmi Napitu, Kandaga Pujiana, R. Dwi Susanto, Bernadette Sloyan, Beatriz Peña-Molino, Dongliang Yuan, Nelly Florida Riama, Siswanto Siswanto, Anastasia Kuswardani, Zainal Arifin, A'an J. Wahyudi, Hui Zhou, Taira Nagai, Joseph K. Ansong, Romain Bourdalle-Badié, Jerome Chanut, Florent Lyard, Brian K. Arbic, Andri Ramdhani, and Agus Setiawan

Subjects
Indonesian throughflow, observing system, intraseasonal, ENSO, transport variability, planetary waves, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Published
2019
Full Text
View/download PDF

4. Detecting Change in the Indonesian Seas

Author

Janet Sprintall, Arnold L. Gordon, Susan E. Wijffels, Ming Feng, Shijian Hu, Ariane Koch-Larrouy, Helen Phillips, Dwiyoga Nugroho, Asmi Napitu, Kandaga Pujiana, R. Dwi Susanto, Bernadette Sloyan, Beatriz Peña-Molino, Dongliang Yuan, Nelly Florida Riama, Siswanto Siswanto, Anastasia Kuswardani, Zainal Arifin, A’an J. Wahyudi, Hui Zhou, Taira Nagai, Joseph K. Ansong, Romain Bourdalle-Badié, Jerome Chanut, Florent Lyard, Brian K. Arbic, Andri Ramdhani, and Agus Setiawan

Subjects
Indonesian throughflow, observing system, intraseasonal, ENSO, transport variability, planetary waves, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract

The Indonesian seas play a fundamental role in the coupled ocean and climate system with the Indonesian Throughflow (ITF) providing the only tropical pathway connecting the global oceans. Pacific warm pool waters passing through the Indonesian seas are cooled and freshened by strong air-sea fluxes and mixing from internal tides to form a unique water mass that can be tracked across the Indian Ocean basin and beyond. The Indonesian seas lie at the climatological center of the atmospheric deep convection associated with the ascending branch of the Walker Circulation. Regional SST variations cause changes in the surface winds that can shift the center of atmospheric deep convection, subsequently altering the precipitation and ocean circulation patterns within the entire Indo-Pacific region. Recent multi-decadal changes in the wind and buoyancy forcing over the tropical Indo-Pacific have directly affected the vertical profile, strength, and the heat and freshwater transports of the ITF. These changes influence the large-scale sea level, SST, precipitation and wind patterns. Observing long-term changes in mass, heat and freshwater within the Indonesian seas is central to understanding the variability and predictability of the global coupled climate system. Although substantial progress has been made over the past decade in measuring and modeling the physical and biogeochemical variability within the Indonesian seas, large uncertainties remain. A comprehensive strategy is needed for measuring the temporal and spatial scales of variability that govern the various water mass transport streams of the ITF, its connection with the circulation and heat and freshwater inventories and associated air-sea fluxes of the regional and global oceans. This white paper puts forward the design of an observational array using multi-platforms combined with high-resolution models aimed at increasing our quantitative understanding of water mass transformation rates and advection within the Indonesian seas and their impacts on the air-sea climate system.

Published
2019
Full Text
View/download PDF

5. Historical CTD dataset and associated processed dissipation rate using an improved Thorpe method in the Indonesian seas

Author

Agus S. Atmadipoera, Yannis Cuypers, Toshiyuki Hibiya, Taira Nagai, Pascale Bouruet-Aubertot, Adi Purwandana, Processus et interactions de fine échelle océanique (PROTEO), 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), Research Center for Oceanography (RCO), Indonesian Institute of Sciences (LIPI), Department of Earth and Planetary Science [Tokyo], Graduate School of Science [Tokyo], The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo), Bogor Agricultural University - IPB (INDONESIA), 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)), 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), and The University of Tokyo (UTokyo)

Subjects
Vertical mixing, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], lcsh:Computer applications to medicine. Medical informatics, Dissipation rate, Turbulent mixing, Thorpe scale, 03 medical and health sciences, 0302 clinical medicine, 14. Life underwater, lcsh:Science (General), ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, CTD dataset, 0303 health sciences, Multidisciplinary, Spatial structure, Internal tide, Dissipation, Watermass, 13. Climate action, Indonesian seas, Climatology, Turbulence kinetic energy, lcsh:R858-859.7, Earth and Planetary Science, CTD, 030217 neurology & neurosurgery, Geology, lcsh:Q1-390
Abstract

In this article, we present the datasets which are used to estimate the turbulent kinetic energy dissipation rates and vertical diffusivity in the Indonesian seas. An archived CTD (conductivity, temperature, depth) datasets collected between 1990 and 2016 with 1 m vertical resolution is presented and analyzed using an improved Thorpe method. The direct estimates dataset of the dissipation rate from two research expeditions, i.e., INDOMIX Program in 2010 and TOMTOM Program in 2015 were also presented, available to be compared with the indirect estimates from CTD profiles. We also present the dissipation rate output of three recent regional internal tide models in the Indonesian seas for comparison with microstructure measurements and improved Thorpe estimates. The datasets refer to "Spatial structure of turbulent mixing inferred from historical CTD datasets in the Indonesian seas" [1].

Published
2020
Full Text
View/download PDF

6. Spatial structure of turbulent mixing inferred from historical CTD datasets in the Indonesian seas

Author

Agus S. Atmadipoera, Toshiyuki Hibiya, Yannis Cuypers, Pascale Bouruet-Aubertot, Adi Purwandana, Taira Nagai, Processus et interactions de fine échelle océanique (PROTEO), 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), Research Center for Oceanography (RCO), Indonesian Institute of Sciences (LIPI), Department of Earth and Planetary Sciences [TITECH Tokyo], Tokyo Institute of Technology [Tokyo] (TITECH), Bogor Agricultural University - IPB (INDONESIA), 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, Pycnocline, Throughflow, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, Internal tide, Mesoscale meteorology, Geology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Dissipation, 01 natural sciences, Salinity, Oceanography, Turbulence kinetic energy, Common spatial pattern, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Turbulent kinetic energy dissipation rates and vertical diffusivities in the Indonesian seas are inferred from historical CTD measurements gathering for the first time data from Indonesian and international cruises. Dissipation rates are inferred from the CTD using an improved Thorpe scale method, which is validated against microstructure measurements. Elevated dissipation rates ~[10−6–10−7] m2 s−3, were observed in the near field stations, such as in the straits, narrowing passages and shallowing topography where internal tides are generated and Indonesian throughflow (ITF) is intense, while lower dissipation rates ~[10−8–10−10] m2 s−3 were observed in the far field stations and below the pycnocline. The main mixing hot spots are located in the Labani Channel and shallowing topography of the Dewakang waters for the western route of ITF, i.e. the passage that connects the north Pacific source via Sulawesi Sea, Makassar Strait and Flores Sea; in the straits of Halmahera, Lifamatola, and Buru for the eastern route of ITF, i.e. the passage that connects the south Pacific source via Halmahera Sea, Maluku Sea, Seram Sea; and in the ITF exit passages, i.e. the Lombok, Sape and Ombai Straits. The eastern route is more dissipative than the western route, which is consistent with the stronger erosion of the salinity peak of the Pacific waters along the eastern route. We found that tidal variations influence the dissipation rates and diffusivities as has been suggested from the yoyo profiling datasets. The spatial pattern of dissipation rates inferred from the high-resolution 3D hydrodynamics model output of Nagai and Hibiya (2015) shows a general agreement with the observations in the location of the mixing hot spots and suggests that the M2 internal tide is the dominant factor driving the turbulent kinetic energy dissipation rates in the Indonesian seas. Yet the model also shows a bias toward lower dissipation rate in the pycnocline, that we attribute to the lack of representation of the ITF and mesoscale circulation and a bias toward higher dissipation rate in the weak mixing region, suggesting an overestimation of the background dissipation rate in calm waters.

Published
2020
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results