Updated on 2022/03/26

写真a

 
AIKI Hidenori
 
Organization
Institute for Space-Earth Environmental Research Division for Land-Ocean Ecosystem Research Associate professor
Graduate School
Graduate School of Environmental Studies
Title
Associate professor
Contact information
メールアドレス

Degree 1

  1. 博士(理学) ( 2003.3   東京大学 ) 

Research Interests 4

  1. coupled numerical simulation for coastal environment

  2. air-sea boundary layer

  3. global wave dynamcis

  4. physical oceanography

Research Areas 1

  1. Natural Science / Atmospheric and hydrospheric sciences

Current Research Project and SDGs 2

  1. 海洋圏の環境・災害問題についての数値シミュレーション

  2. 太平洋・インド洋・大西洋・南大洋における各種波動と気候変動の相互関係の解析

Research History 9

  1. Nagoya University   Graduate School of Environmental Studies Department of Earth and Environmental Sciences   Associate Professor

    2016.1

  2. Associate Professor, Nagoya University

    2016

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    Country:Japan

  3. Senior Research Scientist, JAMSTEC

    2010 - 2015

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    Country:Japan

  4. Visiting Research Scholar, University of Hawaii

    2007 - 2008

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    Country:Japan

  5. Postdoctoral Fellow for Research Abroad, JSPS

    2007 - 2008

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    Country:Japan

  6. Research Scientist, JAMSTEC

    2005 - 2009

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    Country:Japan

  7. Postdoctoral Fellow, JAMSTEC

    2003 - 2004

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    Country:Japan

  8. Assistant Researcher, National Space Development Agency

    2001 - 2002

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    Country:Japan

  9. Research Scholar, JSPS

    1998 - 2000

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    Country:Japan

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Education 3

  1. The University of Tokyo   Graduate School, Division of Science   Department of Earty and Planetary Science

    1998.4 - 2001.3

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    Country: Japan

  2. The University of Tokyo   Graduate School, Division of Science   Department of Earty and Planetary Physics

    1996.4 - 1998.3

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    Country: Japan

  3. Nagoya University   Faculty of Science

    1992.4 - 1996.3

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    Country: Japan

Professional Memberships 3

  1. 流体力学会

  2. 気象学会

  3. 海洋学会

Awards 3

  1. Editor's Award

    2019   American Meteorological Society   Journal of Physical Oceanography

    Hidenori Aiki

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    Award type:Honored in official journal of a scientific society, scientific journal 

    https://www.ametsoc.org/index.cfm/ams/about-ams/ams-awards-honors/2019-awards-and-honors-recipients/

  2. Editor's Citation for Excellence in Refereeing

    2015.5   American Geophysical Union  

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    Country:United States

  3. The Ryumon Medal

    2004.9   Japan Society of Fluid Mechanics  

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    Country:Japan

 

Papers 33

  1. Towards a seamlessly diagnosable expression for the energy flux associated with both equatorial and mid-latitude waves Invited Reviewed

    Hidenori Aiki, Richard J. Greatbatch, Martin Claus

    Progress of Earth and Planetaty Science   Vol. 4   2017.3

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1186/s40645-017-0121-1

  2. Projection of Future Enhancement of Heavy Rainfalls Associated Using a Regional 1-km-mesh Atmosphere-Ocean Coupled Model

    Kanada Sachie, Aiki Hidenori, Tsuboki Kazuhisa

    SOLA   Vol. 17A   page: 38 - 44   2021.7

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    Language:Japanese  

    DOI: 10.2151/sola.17A-007

    Web of Science

  3. The 1994 positive Indian Ocean Dipole event as investigated by the transfer routes of oceanic wave energy Reviewed

    Zimeng Li, Hidenori Aiki

    Journal of Physical Oceanography     2022.1

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    Authorship:Last author   Publishing type:Research paper (scientific journal)   Publisher:American Meteorological Society  

    <title>Abstract</title>
    The present study investigates the interannual variability of the tropical Indian Ocean (IO) based on the transfer routes of wave energy in a set of 61-year hindcast experiments using a linear ocean model. To understand the basic feature of the IO Dipole mode, this paper focuses on the 1994 pure positive event. Two sets of westward transfer episodes in the energy flux associated with Rossby waves (RWs) are identified along the equator during 1994. One set represents the same phase speed as the linear theory of equatorial RWs, while the other set is slightly slower than the theoretical phase speed. The first set originates from the reflection of equatorial Kelvin waves at the eastern boundary of the IO. On the other hand, the second set is found to be associated with off-equatorial RWs generated by southeasterly winds in the southeastern IO, which may account for the appearance of the slower group velocity. A combined empirical orthogonal function (EOF) analysis of energy-flux streamfunction and potential reveals the intense westward signals of energy flux are attributed to off-equatorial RWs associated with predominant wind input in the southeastern IO corresponding to the positive IO Dipole event.

    DOI: 10.1175/jpo-d-21-0189.1

  4. Decadal vision in oceanography 2021: Air―sea boundary Invited Reviewed

    Yoko Iwamoto, Hidenori Aiki, Osamu Isoguchi, Yumiko Obayashi, Fumiyoshi Kondo, Yoshiko Kondo, and Jun Nishioka

    Oceanography in Japan   Vol. 30 ( 5 ) page: 199 - 225   2021.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Oceanographic Society of Japan  

    DOI: 10.5928/kaiyou.30.5_199

  5. The energy flux of three-dimensional waves in the atmosphere: Exact expression for a basic model diagnosis with no equatorial gap Reviewed

    Hidenori Aiki, Yoshiki Fukutomi, Yuki Kanno, Tomomichi Ogata, Takahiro Toyoda, Hideyuki Nakano

    Journal of the Atmospheric Sciences   Vol. 78 ( 11 ) page: 3745 - 3758   2021.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:American Meteorological Society  

    <title>Abstract</title>A model diagnosis for the energy flux of off-equatorial Rossby waves in the atmosphere has previously been done using quasi-geostrophic equations and is singular at the equator. The energy flux of equatorial waves has been separately investigated in previous studies using a space-time spectral analysis or a ray theory. A recent analytical study has derived an exact universal expression for the energy flux which can indicate the direction of the group velocity for linear shallow water waves at all latitudes. This analytical result is extended in the present study to a height-dependent framework for three-dimensional waves in the atmosphere. This is achieved by investigating the classical analytical solution of both equatorial and off-equatorial waves in a Boussinesq fluid. For the horizontal component of the energy flux, the same expression has been obtained between equatorial waves and off-equatorial waves in the height-dependent framework, which is linked to a scalar quantity inverted from the isentropic perturbation of Ertel’s potential vorticity. The expression of the vertical component of the energy flux requires computation of another scalar quantity that may be obtained from the meridional integral of geopotential anomaly in a wavenumber-frequency space. The exact version of the universal expression is explored and illustrated for three-dimensional waves induced by an idealized Madden-Julian Oscillation forcing in a basic model experiment. The zonal and vertical fluxes manifest the energy transfer of both equatorial Kelvin waves and off-equatorial Rossby waves with a smooth transition at around 10°S and around 10°N. The meridional flux of wave energy represents connection between off-equatorial divergence regions and equatorial convergence regions.

    DOI: 10.1175/JAS-D-20-0177.1

    Web of Science

    Other Link: https://journals.ametsoc.org/downloadpdf/journals/atsc/aop/JAS-D-20-0177.1/JAS-D-20-0177.1.xml

  6. Horizontal energy flux of wind-driven intraseasonal waves in the tropical Atlantic by a unified diagnosis Reviewed

    Qingyang Song, Hidenori Aiki

    Journal of Physical Oceanography   Vol. 51 ( 9 ) page: 3037 - 3050   2021.9

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:American Meteorological Society  

    <title>Abstract</title>Intraseasonal waves in the tropical Atlantic Ocean have been found to carry prominent energy that affects interannual variability of zonal currents. This study investigates energy transfer and interaction of wind-driven intraseasonal waves using single-layer model experiments. Three sets of wind stress forcing at intraseasonal periods of around 30 days, 50 days and 80 days with a realistic horizontal distribution are employed separately to excite the second baroclinic mode in the tropical Atlantic. A unified scheme for calculating the energy flux, previously approximated and used for the diagnosis of annual Kelvin and Rossby waves, is utilized in the present study in its original form for intraseasonal waves. Zonal velocity anomalies by Kelvin waves dominate the 80-day scenario. Meridional velocity anomalies by Yanai waves dominate the 30-day scenario. In the 50-day scenario, the two waves have comparable magnitudes. The horizontal distribution of wave energy flux is revealed. In the 30-day and 50-day scenarios, a zonally alternating distribution of cross-equatorial wave energy flux is found. By checking an analytical solution excluding Kelvin waves, we confirm that the cross-equatorial flux is caused by the meridional transport of geopotential at the equator. This is attributed to the combination of Kelvin and Yanai waves and leads to the asymmetric distribution of wave energy in the central basin. Coastally-trapped Kelvin waves along the African coast are identified by along-shore energy flux. In the north, the bend of the Guinea coast leads the flux back to the equatorial basin. In the south, the Kelvin waves strengthened by local wind transfer the energy from the equatorial to Angolan regions.

    DOI: 10.1175/JPO-D-20-0262.1

    Web of Science

    Other Link: https://journals.ametsoc.org/downloadpdf/journals/phoc/aop/JPO-D-20-0262.1/JPO-D-20-0262.1.xml

  7. The vertical structure of annual wave energy flux in the tropical Indian Ocean Reviewed

    Zimeng Li, Hidenori Aiki, Motoki Nagura, Tomomichi Ogata

    Progress in Earth and Planetary Science   Vol. 8 ( 1 )   2021.7

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    <title>Abstract</title>A recently developed energy flux diagnosis scheme, which incorporates a smooth connection between the tropical and subtropical zones, is used in the present study to investigate vertically propagating waves in the tropical Indian Ocean (IO) based on the result of a linear, continuously stratified ocean model driven by climatological wind forcing. This extended diagnosis reveals deep-reaching eastward energy fluxes at the equator which develop four times per year and are associated with equatorial Kelvin waves (KWs) generated by semiannual winds. The authors find that the downward transfer of wave energy is particularly deep in the southern Bay of Bengal (SBoB). This downward flux is attributed to off-equatorial Rossby waves and appears four times per year, maximizing its amplitude during November–December. Southwesterly winds in the Arabian Sea intensify eastward energy flux of KWs at mid-depth, which maximizes in amplitude in August. This is contrastive to KW energy flux at the surface which peaks in May. These mid-depth equatorial KW packets subsequently arrive at the eastern boundary of the IO and are diffracted poleward to produce downward energy flux in November and December detected in the SBoB.

    DOI: 10.1186/s40645-021-00432-9

    Web of Science

    Other Link: https://link.springer.com/article/10.1186/s40645-021-00432-9/fulltext.html

  8. Energy flow diagnosis of ENSO from an ocean reanalysis Reviewed

    Takahiro Toyoda, Hideyuki Nakano, Hidenori Aiki, Tomomiti Ogata, Yoshiki Fukutomi, Yuki Kanno, L. Shogo Urakawa, Kei Sakamoto, Goro Yamanaka, Motoki Nagura

    Journal of Climate   Vol. 34 ( 10 ) page: 4023 - 4042   2021.5

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:American Meteorological Society  

    <title>Abstract</title>A method is introduced for diagnosing the time evolution of wave energy associated with ENSO from an ocean reanalysis. In the diagnosis, time changes of kinetic and available potential energy are mainly represented by energy inputs caused by surface wind stress and horizontal energy fluxes for each vertically decomposed normal mode. The resulting time evolutions of the wave energy and vertical thermocline displacements in the 1997–1998 and 2014–2016 El Niño events are consistent with our previous knowledge of these events. Further, our result indicated that representation of several vertical modes is necessary to reproduce the broadly distributed downward thermocline displacements in the central to eastern equatorial Pacific, generated by a westerly wind event in the western equatorial Pacific (e.g., in March 1997), that are preconditioning for El Niño development. In addition, we investigated the wave energy budget, including the influence of data assimilation, on the complicated time evolution of equatorial thermocline displacements caused by repeated westerly and easterly wind events during the 2014–2016 El Niño event. Our result suggests that noise from a momentum imbalance near the equator associated with data assimilation, which possibly affected the El Niño prediction failure in 2014, was much reduced by our developed ocean data assimilation system and reanalysis. This study, which provides a new connection between the theoretical works and reanalysis products that use sophisticated systems for synthesizing OGCMs and observations, should be useful for climate research and operational communities interested in ENSO.

    DOI: 10.1175/JCLI-D-20-0704.1

    Web of Science

    Other Link: https://journals.ametsoc.org/downloadpdf/journals/clim/aop/JCLI-D-20-0704.1/JCLI-D-20-0704.1.xml

  9. Future Changes of a Slow-Moving Intense Typhoon with Global Warming: A Case Study Using a Regional 1-km-mesh Atmosphere–Ocean Coupled Model Reviewed

    Sachie Kanada, Hidenori Aiki, Kazuhisa Tsuboki, Izuru Takayabu

    SOLA   Vol. 17A ( Special_Edition ) page: 14 - 20   2021.1

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Meteorological Society of Japan  

    DOI: 10.2151/sola.17A-003

    Web of Science

  10. 10 Hz測定光学粒子計による海上波浪境界層観測 Invited Reviewed

    相木 秀則, 近藤 文義, 根田 昌典, 田中 潔, 藤田 敏男

    エアロゾル研究   Vol. 35 ( 3 ) page: 160 - 169   2020.9

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

  11. A global eddying hindcast ocean simulation with OFES2 Reviewed

    Hideharu Sasaki, Shinichiro Kida, Ryo Furue, Hidenori Aiki, Nobumasa Komori, Yukio Masumoto, Toru Miyama, Masami Nonaka, Yoshikazu Sasai, Bunmei Taguchi

    GEOSCIENTIFIC MODEL DEVELOPMENT   Vol. 13 ( 7 ) page: 3319 - 3336   2020.7

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:COPERNICUS GESELLSCHAFT MBH  

    A quasi-global eddying ocean hindcast simulation using a new version of our model, called OFES2 (Ocean General Circulation Model for the Earth Simulator version 2), was conducted to overcome several issues with unrealistic properties in its previous version, OFES. This paper describes the model and the simulated oceanic fields in OFES2 compared with OFES and also observed data. OFES2 includes a sea-ice model and a tidal mixing scheme, is forced by a newly created surface atmospheric dataset called JRA55-do, and simulated the oceanic fields from 1958 to 2016. We found several improvements in OFES2 over OFES: smaller biases in the global sea surface temperature and sea surface salinity as well as the water mass properties in the Indonesian and Arabian seas. The time series of the Nino3.4 and Indian Ocean Dipole (IOD) indexes are somewhat better in OFES2 than in OFES. Unlike the previous version, OFES2 reproduces more realistic anomalously low sea surface temperatures during a positive IOD event. One possible cause of these improvements in El Nino and IOD events is the replacement of the atmospheric dataset. On the other hand, several issues remained unrealistic, such as the pathways of the Kuroshio and Gulf Stream and the unrealistic spreading of salty Mediterranean overflow. Given the worldwide use of the previous version and the improvements presented here, the output from OFES2 will be useful in studying various oceanic phenomena with broad spatiotemporal scales.

    DOI: 10.5194/gmd-13-3319-2020

    Web of Science

  12. The Climatological Horizontal Pattern of Energy Flux in the Tropical Atlantic as Identified by a Unified Diagnosis for Rossby and Kelvin Waves Reviewed

    Qingyang Song, Hidenori Aiki

    JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS   Vol. 125 ( 2 )   2020.2

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:AMER GEOPHYSICAL UNION  

    This study investigates the horizontal distribution of wave energy flux in the tropical Atlantic Ocean using shallow-water model experiments for three gravest baroclinic modes forced by climatological winds. This is the first attempt to apply a unified diagnostic scheme to the analysis of energy fluxes associated with both Rossby waves (RWs) and Kelvin waves (KWs) in the tropical Atlantic Ocean. Those analyses were difficult in previous studies owing to the difference of equatorial and quasigeostrophic dynamics. The scheme yields the transfer route (i.e., trajectories by group velocity vector) of wave energy originating from both local wind forcing and boundary reflection. The meridional flux of wave energy crossing two zonal sections (at 3 degrees N and at 2 degrees S) is examined for understanding where the equatorial and off-equatorial regions interconnect. Equatorward energy fluxes into the basin interior are found mainly on the zonal section in the Northern Hemisphere (at 3 degrees N), indicating the radiation of RWs from the Guinea coast. At the equator, seasonal transition in May from eastward wind anomaly to westward anomaly yields a significant energy input at the central basin that radiates both RWs and KWs. The energy flux of these RWs arrives at the western boundary in September, followed by reflection of KWs to yield eastward transbasin energy fluxes in October-December. The analysis also identifies an unexpected wind input in May at 4 degrees S which induces both RWs and inertial gravity waves.Plain Language Summary Propagation, diffraction, and reflection of large-scale waves play an important role in tropical climate variations. Horizontal energy fluxes associated with Rossby and Kelvin wave interaction have been little investigated owing to the lack of an appropriate diagnostic scheme in previous studies. A recent study has developed a diagnostic scheme which can reveal the trajectory of the group velocity of both Rossby and Kelvin waves with satisfying coastal boundary conditions. This scheme has been used in the present study to investigate energetics in the output of climatological model experiments. At the equator, seasonal transition in May from eastward wind anomaly to westward anomaly yields a significant energy input at the central basin that radiates both Rossby and Kelvin waves. The energy flux of these Rossby waves arrives at the western boundary in September, followed by reflection of Kelvin waves to yield eastward transbasin energy fluxes in October-December. The unified scheme may be used to understand the impact of tropical climate variations to off-equatorial regions and vice versa in a future study.

    DOI: 10.1029/2019JC015407

    Web of Science

  13. The Life Cycle of Annual Waves in the Indian Ocean as Identified by Seamless Diagnosis of the Energy Flux Reviewed

    Zimeng Li, Hidenori Aiki

    GEOPHYSICAL RESEARCH LETTERS   Vol. 47 ( 2 )   2020.1

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:AMER GEOPHYSICAL UNION  

    In previous studies, the role of large-scale waves in tropical-extratropical interactions has been little investigated in terms of wave energy transfer owing to the lack of appropriate diagnostic techniques. Using a new seamless scheme, the present study identifies a series of well-defined horizontal circulation routes of wave energy in the Indian Ocean on an annual basis. One of these features represents a localized cyclonic circulation close to the western boundary in each hemisphere while the other manifests as a basin-scale cyclonic circulation in the eastern Indian Ocean. For the second baroclinic mode, eastward energy fluxes associated with equatorial Kelvin waves appear when zonal velocity anomaly exhibits eastward and westward peaks (four times per year) in response to the monsoon-wind cycle. Identification of these key pathways of wave energy circulation enables us to better understand how waves in the tropical and subtropical regions interconnect at the zonal boundaries of the Indian Ocean.

    DOI: 10.1029/2019GL085670

    Web of Science

  14. The Pathway of Intraseasonal Wave Energy in the Tropical Indian Ocean as Identified by a Seamless Diagnostic Scheme Reviewed

    Tomomichi Ogata, Hidenori Aiki

    SOLA   Vol. 15   page: 262 - 267   2019.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:METEOROLOGICAL SOC JAPAN  

    This study makes a first attempt to apply the diagnostic scheme of Aiki et al. (2017) to the output of an ocean general circulation model (OGCM), in order to investigate the basin-wide pathway of equatorial and mid-latitude wave energy associated with intraseasonal variability in the Indian Ocean. The vertical mode decomposition shows that 90-day variability of the second baroclinic mode is dominant in a realistic OGCM experiment. For 90-day equatorial Kelvin wave (KW) and Rossby wave (RW), energy input by wind stress appears in the eastern equatorial Indian Ocean that is then transferred eastward by KWs along the eastern equatorial waveguide (while westward as RW off equator). For 30-day Mixed-Rossby Gravity waves (MRG), wave energy is transferred eastward while wave phase propagates westward that is consistent with the dispersion relationship of low-frequency MRG. The new diagnostic scheme is able to show, particularly for 30-day MRG, eastward energy fluxes along the equatorial waveguide, while the other schemes in previous studies (e.g. pressure flux, quasi-geostrophic flux) cannot show the direction of the group velocity of equatorial waves.

    DOI: 10.2151/sola.2019-047

    Web of Science

  15. Future Changes in Typhoon-Related Precipitation in Eastern Hokkaido Reviewed

    Sachie Kanada, Hidenori Aiki, Kazuhisa Tsuboki, Izuru Takayabu

    SOLA   Vol. 15   page: 244 - 249   2019.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:METEOROLOGICAL SOC JAPAN  

    From 16 to 23 August 2016, typhoons T1607, T1609, and T1611 hit eastern Hokkaido in northern Japan and caused heavy rainfall that resulted in severe disasters. To understand future changes in typhoon-related precipitation (TRP) in midlatitude regions, climate change experiments on these three typhoons were conducted using a high-resolution three-dimensional atmosphere-ocean coupled regional model in current and pseudo-global warming (PGW) climates. All PGW simulations projected decreases in precipitation frequency with an increased frequency of strong TRP and decreased frequency of weak TRP in eastern Hokkaido. In the current climate, snow-dominant precipitation systems start to cause precipitation in eastern Hokkaido about 24 hours before landfall. In the PGW climate, increases in convective available potential energy (CAPE) developed tall and intense updrafts and the snow-dominant precipitation systems turned to have more convective property with less snow mixing ratio (QS). Decreased QS reduced precipitation area, although strong precipitation increased or remained almost the same. Only TRP of T1607 increased the amounts before landfall. In contrast, all typhoons projected to increase TRP amount associated with landfall, because in addition to increased CAPE, the PGW typhoon and thereby its circulations intensified, and a large amount of rain was produced in the core region.

    DOI: 10.2151/sola.2019-044

    Web of Science

  16. Flood Simulations in Mid-Latitude Agricultural Land Using Regional Current and Future Extreme Weathers Reviewed

    Nobuaki Kimura, Hirohide Kiri, Sachie Kanada, Iwao Kitagawa, Ikuo Yoshinaga, Hidenori Aiki

    WATER   Vol. 11 ( 11 )   2019.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:MDPI  

    Recent extreme weather events like the August 2016 flood disaster have significantly affected farmland in mid-latitude regions like the Tokachi River (TR) watershed, the most productive farmland in Japan. The August 2016 flood disaster was caused by multiple typhoons that occurred in the span of two weeks and dealt catastrophic damage to agricultural land. This disaster was the focus of our flood model simulations. For the hydrological model input, the rainfall data with 0.04 degrees grid space and an hourly interval were provided by a regional climate model (RCM) during the period of multiple typhoon occurrences. The high-resolution data can take account of the geographic effects, hardly reproduced by ordinary RCMs. The rainfall data drove a conceptual, distributed rainfall-runoff model, embedded in the integrated flood analysis system. The rainfall-runoff model provided discharges along rivers over the TR watershed. The RCM also provided future rainfall data with pseudo-global warming climate, assuming that the August 2016 disaster could reoccur again in the late 21st century. The future rainfall data were used to conduct a future flood simulation. With bias corrections, current and future flood simulations showed the potential inundated areas along riverbanks based on flood risk levels. The crop field-based agricultural losses in both simulations were estimated. The future cost may be two to three times higher as indicated by slightly higher simulated future discharge peaks in tributaries.

    DOI: 10.3390/w11112421

    Web of Science

  17. Salinity frontogenesis/frontolysis in the northeastern subtropical Pacific region Reviewed

    Shun Ohishi, Shota Katsura, Hidenori Aiki

    CLIMATE DYNAMICS   Vol. 53 ( 9-10 ) page: 5927 - 5943   2019.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    Detailed mechanisms of reinforcement/relaxation of a sea surface salinity front, i.e. frontogenesis/frontolysis, in the northeastern subtropical Pacific region are investigated using observational datasets. Throughout the year, meridional shears of zonal wind induce meridional ageostrophic convergence around the front. Saltier water is advected on the southern side than the northern side, and thus the convergence contributes to frontogenesis. The evaporation and precipitation gradients also strengthen the front, because higher sea surface temperatures on the southern side induce stronger evaporation through the formation of higher surface saturated specific humidity, and because the precipitation rate is low in the southern region in association with the subtropical high of the atmosphere. However, in summer-autumn when the mixed layer is seasonally thin and evaporation exceeds precipitation, the frontogenesis by the freshwater flux gradient is damped by the mixed layer depth (MLD) gradient. This is attributed to the thicker mixed layer south of the front being less sensitive to freshwater fluxes. During the mixed-layer deepening phase, the mixed layer on the southern side entrains lower salinity water from the lower layer, and thus the entrainment relaxes the front. Therefore, it is shown that the gradients of ageostrophic advection, evaporation, and precipitation result in frontogenesis, while those of MLD and entrainment cause frontolysis. Furthermore, a metric that quantifies the relative importance of the horizontal gradients of freshwater fluxes and MLD for salinity frontogenesis/frontolysis is proposed. Over the large domain, contribution from the horizontal gradient of freshwater fluxes dominates over that of MLD.

    DOI: 10.1007/s00382-019-04907-w

    Web of Science

  18. Frontolysis by surface heat flux in the eastern Japan Sea: importance of mixed layer depth Reviewed

    Shun Ohishi, Hidenori Aiki, Tomoki Tozuka, Meghan F. Cronin

    JOURNAL OF OCEANOGRAPHY   Vol. 75 ( 3 ) page: 283 - 297   2019.6

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    Frontolysis mechanisms by which surface heat flux relaxes the sea surface temperature (SST) front in the eastern Japan Sea (JS) are investigated in detail using observational datasets. On the warm southern side of the front, larger air-sea specific humidity and temperature differences induce stronger turbulent heat release compared to the cool northern side. As a result, stronger wintertime cooling and weaker summertime warming occur south of the front, and the meridional gradient in the surface net heat flux (NHF) tends to relax the SST front throughout the year. In the mixed-layer deepening phase (September-January), a higher entrainment velocity occurs on the warm southern side because of weaker stratification. Since the resulting thicker mixed layer on the southern side is less sensitive to surface cooling, the mixed layer depth (MLD) gradient damps the frontolysis by the NHF gradient. In the shoaling phase (April-June), a deeper mixed layer south of the front is caused by the weaker warming and reduced sensitivity of the thicker mixed layer to a shoaling effect by shortwave radiation. Owing to weaker sensitivity of the thicker mixed layer on the southern side to surface warming, the MLD gradient enhances the frontolysis by the NHF gradient. Therefore, it is shown that the mixed layer processes cause seasonality of weaker (stronger) frontolysisby surface heat fluxes, damping (enhancing) the frontolysis by the NHF gradient in winter (summer). This study reveals unique features of the frontolysis in the eastern JS compared with the Agulhas Return Current and Kuroshio Extension regions.

    DOI: 10.1007/s10872-018-0502-0

    Web of Science

  19. One-Dimensional Turbulence-Ecosystem Model Reveals the Triggers of the Spring Bloom in Mesoscale Eddies

    E. R. Maúre, J. Ishizaka, H. Aiki, Y. Mino, N. Yoshie, J. I. Goes, J. I. Goes, H. R. Gomes, H. R. Gomes, H. Tomita

    Journal of Geophysical Research: Oceans   Vol. 123 ( 9 ) page: 6841 - 6860   2018.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    ©2018. American Geophysical Union. All Rights Reserved. A lower trophic ecosystem model coupled with a one-dimensional physical turbulence closure model was applied to study phytoplankton dynamics and spring bloom initiation in mesoscale anticyclonic eddies (AEs) and cyclonic eddies (CEs). The model simulated ecosystem dynamics between nutrient-phytoplankton-zooplankton-detritus in AEs and CEs, while the physical model provided the seasonal cycle of convective turbulent mixing. The study was motivated by earlier work based on satellite and ship observations, which showed earlier initiation of the spring blooms in CEs with shallow mixed-layer depths than in AEs with deeper mixed-layer depths. The model results supported the hypothesis that mixed-layer depths in eddies play an important role in the dynamics of the spring bloom initiation. Model results revealed that in AEs convective mixing causes light limitation for phytoplankton growth due to deep winter mixing, and the bloom initiation is delayed until relaxation of turbulent convective mixing. Conversely, in the shallow mixed-layer CEs, blooms initiate before the end of convective mixing due to early improvement in light conditions following the increase in solar radiation. Furthermore, the model showed that the relaxation in zooplankton grazing for the deep mixing contributed to weak winter phytoplankton accumulation in AE, while winter phytoplankton accumulation was faster in the shallow mixed-layer CE. Overall, the initiation mechanism and the dynamics of the spring phytoplankton blooms are different for AEs and CEs. Therefore, we suggest that, in many parts of the global ocean, eddies play an important role regulating the dynamics of phytoplankton blooms.

    DOI: 10.1029/2018JC014089

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    Scopus

  20. Impact of cyclonic eddies and typhoons on biogeochemistry in the oligotrophic ocean based on biogeochemical/physical/meteorological time-series at station KEO Reviewed

    Makio C. Honda, Yoshikazu Sasai, Eko Siswanto, Akira Kuwano-Yoshida, Hidenori Aiki, Meghan F. Cronin

    PROGRESS IN EARTH AND PLANETARY SCIENCE   Vol. 5   2018.8

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    In 2014, a sediment trap mooring was deployed adjacent to station Kuroshio Extension Observatory (KEO)'s National Ocean and Atmosphere Administration (NOAA) surface mooring. These data, from July 2014 to July 2016, are used here to investigate nutrient supply mechanisms that support ocean productivity in this oligotrophic region of the subtropical western North Pacific. Both years of sediment trap data show that biogenic material fluxes at similar to 5000 m increased between late winter (March) and late spring (June). Based on sea surface temperature and upper ocean water temperature profiles, from the NOAA surface buoy, and satellite-based surface chlorophyll-alpha, this increase was likely due to an increase of ocean productivity in early spring (March) that was supported by nutrients supplied by winter mixing. On the other hand, biogenic material fluxes also increased in October 2014, and between late December 2014 and January 2015 when concentrations of nutrients near the surface typically are low. Sea surface height anomalies and vertical profiles of water temperature in the upper 500 m showed cyclonic eddies passing station KEO and causing upwelling in late July-early August 2014 and November 2014. It appears that these events supplied nutrients to the upper layer, which then caused ocean productivity in the subsurface layer to temporally increase, resulting in increased deep biogenic material fluxes in autumn and winter. This interpretation of the data is consistent with a simple 3D physical- biological model simulation that shows meso-scale cyclonic eddies can supply nutrient to support new production at KEO. During the 2-year-long sediment trap deployments, several typhoons also passed near station KEO and near-inertial internal waves were observed near the nitracline depth after the typhoons passed. Although turbulent mixing caused by near-inertial internal wave could have possibly supplied nutrient to upper oligotrophic euphotic layer, numerical simulations of the turbulent nutrient supply indicate that enhanced turbulent diffusion across the nutrient concentration gradient did not supply enough nitrate to support the increase in biogenic material flux in autumn.

    DOI: 10.1186/s40645-018-0196-3

    Web of Science

  21. Impacts of SST Patterns on Rapid Intensification of Typhoon Megi (2010) Reviewed

    Sachie Kanada, Satoki Tsujino, Hidenori Aiki, Mayumi K. Yoshioka, Yasumasa Miyazawa, Kazuhisa Tsuboki, Izuru Takayabu

    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES   Vol. 122 ( 24 ) page: 13245 - 13262   2017.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER GEOPHYSICAL UNION  

    Typhoon Megi (2010), a very intense tropical cyclone with a minimum central pressure of 885 hPa, was characterized by especially rapid intensification. We investigated this intensification process by a simulation experiment using a high-resolution (0.02 degrees x0.02 degrees) three-dimensional atmosphere-ocean coupled regional model. We also performed a sensitivity experiment with a time-fixed sea surface temperature (SST). The coupled model successfully simulated the minimum central pressure of Typhoon Megi, whereas the fixed SST experiment simulated an excessively low minimum central pressure of 839 hPa. The simulation results also showed a close relationship between the radial SST profiles and the rapid intensification process. Because the warm sea increased near-surface water vapor and hence the convective available potential energy, the high SST in the eye region facilitated tall and intense updrafts inside the radius of maximum wind speed and led to the start of rapid intensification. In contrast, high SST outside this radius induced local secondary updrafts that inhibited rapid intensification even if the mean SST in the core region exceeded 29.0 degrees C. These secondary updrafts moved inward and eventually merged with the primary eyewall updrafts. Then the storm intensified rapidly when the high SST appeared in the eye region. Thus, the changes in the local SST pattern around the storm center strongly affected the rapid intensification process by modulating the radial structure of core convection. Our results also show that the use of a high-resolution three-dimensional atmosphere-ocean coupled model offers promise for improving intensity forecasts of tropical cyclones.

    DOI: 10.1002/2017JD027252

    Web of Science

    Scopus

  22. Mesoscale Eddies Control the Timing of Spring Phytoplankton Blooms: A Case Study in the Japan Sea Reviewed

    E. R. Maure, J. Ishizaka, C. Sukigara, Y. Mino, H. Aiki, T. Matsuno, H. Tomita, J. I. Goes, H. R. Gomes

    GEOPHYSICAL RESEARCH LETTERS   Vol. 44 ( 21 ) page: 11115 - 11124   2017.11

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    Satellite Chlorophyll a (CHL) data were used to investigate the influence of mesoscale anticyclonic eddies (AEs) and cyclonic eddies (CEs) on the timing of spring phytoplankton bloom initiation around the Yamato Basin (133-139 degrees E and 35-39.5 degrees N) in the Japan Sea, for the period 2002-2011. The results showed significant differences between AEs and CEs in the timing and initiation mechanism of the spring phytoplankton bloom. Blooms were initiated earlier in CEs which were characterized by shallow mixed-layer depths (&lt; 100 m). The early blooming preceded the end of winter cooling (i.e., while net heat flux (Q(0)) is still negative) and is initiated by the increased average light within the shallow mixed-layer depth. Conversely, blooms appeared in the AEs despite deeper mixed-layer depth (&gt; 100 m) but close to the commencement of positive Q(0). This suggests that the relaxation of turbulent mixing is crucial for the bloom initiation in AEs.

    DOI: 10.1002/2017GL074359

    Web of Science

    Scopus

  23. Comments on "A Combined Derivation of the Integrated and Vertically Resolved, Coupled Wave-Current Equations" Reviewed

    Fabrice Ardhuin, Nobuhiro Suzuki, James C. McWilliams, Hidenori Aiki

    JOURNAL OF PHYSICAL OCEANOGRAPHY   Vol. 47 ( 9 ) page: 2377 - 2385   2017.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER METEOROLOGICAL SOC  

    Several equivalent equations for the evolution of the wave-averaged current momentum have been proposed, implemented, and used. In contrast, the equation for the total momentum, which is the sum of the current and wave momenta, has not been widely used because it requires a less practical wave forcing. In an update on previous derivations, Mellor proposed a new formulation of the wave forcing for the total momentum equation. Here, the authors show that this derivation misses a leading-order term that has a zero depth-integrated value. Corrected for this omission, the wave forcing is equivalent to that in the first paper by Mellor. When this wave forcing effect on the currents is approximated it leads to an inconsistency. This study finally repeats and clarifies that the vertical integration of several various forms of the current-only momentum equations are consistent with the known depth-integrated equations for the mean flow momentum obtained by subtracting the wave momentum equation from the total momentum equation. Several other claims in prior Mellor manuscripts are discussed.

    DOI: 10.1175/JPO-D-17-0065.1

    Web of Science

  24. Future Enhancement of Heavy Rainfall Events Associated with a Typhoon in the Midlatitude Regions Reviewed

    Sachie Kanada, Kazuhisa Tsuboki, Hidenori Aiki, Satoki Tsujino, Izuru Takayabu

    SOLA   Vol. 13   page: 246 - 251   2017

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:METEOROLOGICAL SOC JAPAN  

    In August 2016, eastern Hokkaido in northern Japan had unusual typhoon landfalls and experienced heavy rainfall events that caused severe disasters. To understand the impact of global warming on typhoon-related rainfall in such midlatitude regions, numerical experiments on one of the typhoons in August 2016, Typhoon Chanthu, were conducted by using a high-resolution three-dimensional atmosphere-ocean coupled regional model in current and pseudo-global warming (PGW) climates. The amount, intensity, and duration of rainfall in eastern Hokkaido associated with the typhoon increased in the warming climate. The PGW typhoon traveled northward with relatively slower translation speed and resulted in a delay in the landfalls for 6 h. Furthermore, large amounts of near-surface water vapor > 22 g kg(-1) from the southern sea increased the convective instability around eastern Hokkaido and caused tall and intense updrafts. As a result, significant predecessor rainfall events with intense rainfall developed about 24 h before the typhoon landfall. Increased near-surface water vapor in the warming climate also enhanced rainfall associated with the typhoon passage over a widespread area. These results suggest that attention should be paid to future enhancement of heavy rainfall events in the midlatitude regions under global warming.

    DOI: 10.2151/sola.2017-045

    Web of Science

  25. A Divergence-Form Wave-Induced Pressure Inherent in the Extension of the Eliassen-Palm Theory to a Three-Dimensional Framework for All Waves at All Latitudes Reviewed

    Aiki Hidenori, Takaya Koutarou, Greatbatch Richard J.

    JOURNAL OF THE ATMOSPHERIC SCIENCES   Vol. 72 ( 7 ) page: 2822-2849   2015.7

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    DOI: 10.1175/JAS-D-14-0172.1

    Web of Science

  26. A New Expression for the Form Stress Term in the Vertically Lagrangian Mean Framework for the Effect of Surface Waves on the Upper- Ocean Circulation Reviewed

    Aiki Hidenori, Greatbatch Richard J.

    JOURNAL OF PHYSICAL OCEANOGRAPHY   Vol. 44 ( 1 ) page: 3-23   2014.1

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    DOI: 10.1175/JPO-D-12-0228.1

    Web of Science

  27. Editorial-the 4th International Workshop on Modeling the Ocean (IWMO 2012) Reviewed

    Oey Lie-Yauw, Miyazawa Yasumasa, Aiki Hidenori, Masumoto Yukio, Ezer Tal, Waseda Takuji

    OCEAN DYNAMICS   Vol. 63 ( 11-12 ) page: 1345-1347   2013.12

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1007/s10236-013-0658-5

    Web of Science

  28. Layering and turbulence surrounding an anticyclonic oceanic vortex: in situ observations and quasi-geostrophic numerical simulations Reviewed

    Hua Bach Lien, Menesguen Claire, Le Gentil Sylvie, Schopp Richard, Marsset Bruno, Aiki Hidenori

    JOURNAL OF FLUID MECHANICS   Vol. 731   2013.9

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    DOI: 10.1017/jfm.2013.369

    Web of Science

  29. The Vertical Structure of the Surface Wave Radiation Stress for Circulation over a Sloping Bottom as Given by Thickness-Weighted-Mean Theory Reviewed

    Aiki Hidenori, Greatbatch Richard J.

    JOURNAL OF PHYSICAL OCEANOGRAPHY   Vol. 43 ( 1 ) page: 149-164   2013.1

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    DOI: 10.1175/JPO-D-12-059.1

    Web of Science

  30. Thickness-Weighted Mean Theory for the Effect of Surface Gravity Waves on Mean Flows in the Upper Ocean Reviewed

    Aiki Hidenori, Greatbatch Richard J.

    JOURNAL OF PHYSICAL OCEANOGRAPHY   Vol. 42 ( 5 ) page: 725-747   2012.5

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    DOI: 10.1175/JPO-D-11-095.1

    Web of Science

  31. Maintenance of the mean kinetic energy in the global ocean by the barotropic and baroclinic energy routes: the roles of JEBAR and Ekman dynamics Reviewed

    Aiki Hidenori, Richards Kelvin J., Sakuma Hirofumi

    OCEAN DYNAMICS   Vol. 61 ( 5 ) page: 675-700   2011.5

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1007/s10236-011-0382-y

    Web of Science

  32. Energetics of the global ocean: The role of layer-thickness form drag Reviewed

    Aiki Hidenori, Richards Kelvin J.

    JOURNAL OF PHYSICAL OCEANOGRAPHY   Vol. 38 ( 9 ) page: 1845-1869   2008.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1175/2008JPO3820.1

    Web of Science

  33. The Red Sea outflow regulated by the Indian monsoon Reviewed

    Aiki Hidenori, Takahashi Keiko, Yamagata Toshio

    CONTINENTAL SHELF RESEARCH   Vol. 26 ( 12-13 ) page: 1448-1468   2006.8

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    DOI: 10.1016/j.csr.2006.02.017

    Web of Science

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Books 1

  1. Waves, eddies and mean flows in the ocean - the background and outlook of interaction theories, Monograph Series: Meteorological Reseasrch Note, vol. 235, 175 pp

    Hidenori Aiki( Role: Sole author ,  Monograph Series: Meteorological Reseasrch Note, vol. 235, 175 pp)

    Meteorological Society of Japan  2018.3  ( ISBN:9784904129180

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    Language:Japanese Book type:Scholarly book

    https://www.metsoc.jp/2018/03/13/11370

MISC 3

  1. 海洋衛星データ同化システムの構築検討

    沖理子, 可知美佐子, 日原勉, 相木秀則, 大石俊

    宇宙航空研究開発機構特別資料 JAXA-SP-(Web)   ( 20-002 )   2020

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  2. 海洋衛星データ同化システムの構築検討

    中島映至, 可知美佐子, 日原勉, 相木秀則, 宮澤泰正, 大石俊

    宇宙航空研究開発機構特別資料 JAXA-SP-(Web)   ( 18-007 )   2019

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  3. 海洋衛星データ同化システムの構築検討

    松浦直人, 可知美佐子, 日原勉, 相木秀則, 大石俊

    宇宙航空研究開発機構特別資料 JAXA-SP-(Web)   ( 19-002 )   2019

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Research Project for Joint Research, Competitive Funding, etc. 1

  1. 海洋内部の渦形状抵抗の解析とインド太平洋域の中深層循環のモデリング研究

    2007 - 2008

    海外特別研究員 

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    Grant type:Competitive

KAKENHI (Grants-in-Aid for Scientific Research) 10

  1. Development of a sea surface breaking wave observation system using industrial millimeter wave radar and optical particle size counter

    Grant number:21K18652  2021.7 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Research (Exploratory)

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount:\6240000 ( Direct Cost: \4800000 、 Indirect Cost:\1440000 )

  2. 東アジア縁辺海と大気の連鎖的双方向作用とモンスーン変調

    Grant number:19H05698  2019.6 - 2024.3

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    立花 義裕, 柏野 祐二, 榎本 剛, 滝川 哲太郎, 本田 明治, 木田 新一郎, 相木 秀則, 加古 真一郎

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    Authorship:Coinvestigator(s) 

    異常天候をもたらす「犯人」は大気だけなのか?東アジアには縁辺海(東シナ海・黄海・日本海・オホーツク海)が存在する.縁辺海は,海洋上を東進する低気圧の「ゆりかご」である.ゆりかごの中で動く低気圧は,ゆりかごを再び揺らし,また低気圧を揺らす.言い換えれば,「縁辺海上で発生した低気圧に伴って吹く風は海流を駆動し、海流による熱の輸送は水温分布を変える.水温は海面での熱交換を経て気圧分布に反映され風系を変え,その風がまた海流を駆動する.つまり大気と海洋は不可分一体の平衡状態または振動系である」この新概念を,船舶等による機動的観測と技巧的数値実験を融合し,実証することを研究目的とする.
    異常天候をもたらす「犯人」は大気だけなのか?東アジアには縁辺海(東シナ海・黄海・日本海・オホーツク海)が存在する.縁辺海は,海洋上を東進する低気圧の「ゆりかご」である.ゆりかごの中で動く低気圧は,ゆりかごを再び揺らし,また低気圧を揺らす.言い換えれば,「縁辺海上で発生した低気圧に伴って吹く風は海流を駆動し、海流による熱の輸送は水温分布を変える.水温は海面での熱交換を経て気圧分布に反映され風系を変え,その風がまた海流を駆動する.つまり大気と海洋は不可分一体の平衡状態または振動系である」この新概念を船舶等による機動的観測と技巧的数値実験を融合し実証することを研究目的とする.
    2019年度は本格的観測に入る前の観測準備のため,日本海近傍や東シナ海を母港に持つ練習船を有する機関の研究分担者や協力者,そして担当の航海士と船舶観測のすりあわせ等を行った.また測器開発などにも着手した.それに平行して,海洋が大気に及ぼす影響や縁辺海の長期変動に関する数値的統計的研究に開始した.そのための膨大な量の計算出力や観測データを賄うために高速データ計算機能を有する計算機や大型データ保存装置を新たに導入し,計算機や保存装置の設定等を実施した.大気海洋の物理過程が,海洋生物生産過程へ及ぼす影響についての予備調査にも着手した.また気象キャスター等と連携した一般メディアでの情報発信活動も積極的に行った.初年度で予備的段階ではあるが,海氷や海面水温が大気へ遠隔的に及ぼす影響や冷たいオホーツク海が梅雨に及ぼす影響,日本海の水温の長期トレンドなど特筆すべき新たな研究成果が原著論文となった.
    年度末に予定されていた研究集会がコロナで中止となったが,本観測の予備調査を含め観測準備は順調に進んだ.中止となった会合の代替としてオンラインにて会合を行ったことで,研究の遅延を避けることが出来た.また,観測以外の数値的研究は順調に原著論文としてその成果公表することができた.また,当該年度中には災害級の豪雨や度重なる台風災害,そして歴史的暖冬現象に見舞われた.それら諸現象に関する研究にも着手した.一部の成果について学会発表や原著論文として成果を発信した.以上のことから,研究はおおむね順調に進展した.
    2019年度の終盤にコロナ問題が発生したため,2020年度の梅雨期に予定されている観測の実施時期などの再検討を要することとなった.国際学会などでの活動についても制約が出る可能性がある.従って観測的研究はその準備に重点をおくこと,そして観測が本格化するまでは数値的研究を前倒しして研究を進めたい.また,それ以外の研究項目は当初の予定通り進め,2021年度末に予定される冬期観測の準備や大気・海洋の数値実験や観測システム同化実験の整備を実施する.
    以上をふまえ,本計画研究の目的を達成するため,以下の活動に着手または前年度から継続する.
    1) 大気・海洋の数値実験の予備実験を実施する.例えばデザイン設定等は,仮定的においた海面微細構造とそれを解除した設定で予備実験を開始する.予備実験では過去に豪雨や豪雪をもたらした事例を中心に行い,モデリングの結果は翌年の観測計画(集中域の設定など)にも反映させる.
    2) 観測的研究と数値的研究が有機的連携し研究を円滑に行うために,研究の打ち合わせ会合を年度の後半に行う.
    3) WEBやSNSでの情報発信はもちろんのこと気象キャスター等と連携した一般マスメディアでの研究情報発信活動を実施する.

  3. Clarifying the mechanism of tropical climate variability based on the life-cycle analysis of wave energy in the atmosphere and ocean

    Grant number:18H03738  2018.4 - 2022.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

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    Authorship:Principal investigator 

    Grant amount:\44200000 ( Direct Cost: \34000000 、 Indirect Cost:\10200000 )

  4. Atmospheric/Oceanic General circulations in isentropic/isopicnal vertical coordinates

    Grant number:15H02129  2015.4 - 2020.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    IWASAKI TOSHIKI

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    Authorship:Coinvestigator(s) 

    Although the atmospheric dynamics and oceanic dynamics share many similarities, they have been making individual progresses because of difference in target phenomena. In this project, we compare representations of atmospheric general circulation in isentropic coordinates with those of oceanic general circulation in isopycnal coordinates, and create a new common perspective on wave-mean flow interactions. Under adiabatic condition, atmospheric/oceanic parcels move around on isentropic/isopycnal surfaces, respectively. Then, analyzing collective behaviors of fluid parcels help us to make a description of Lagrangian mean. We study formulations of wave-mean flow interactions based on isentropic/isopicnal coordinates, and consistently interpret transports of mass, heat, angular momentum, minor constituents and so on. Also, we investigate cold outbreak of polar cold airmass under a designated potential temperature from a viewpoint of climate change.

  5. Study for the dissipation process of oceanic surface waves and mesoscale eddies based on a complementary approach

    Grant number:26400474  2014.4 - 2018.3

    Hidenori Aiki

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    Authorship:Principal investigator 

    Grant amount:\4810000 ( Direct Cost: \3700000 、 Indirect Cost:\1110000 )

    In previous theories for the atmosphere and ocean, frameworks for the dynamics of midlatitude and equatorial regions have been separated. Thus it has been impossible to continuously trace the life-cycle of wave energy from tropical to extratropical regions. This study has developed a scheme for calculating group velocity that is seamlessly diagnosable for waves at all latitudes and automatically applicable to various types of waves (Rossby, inertia-gravity, and Kelvin waves). The new scheme enables to trace the generation, circulation, and dissipation of wave energy with referring to the direction of group velocity.

  6. 双補完的アプローチによる海洋の中規模渦と海面波浪の消散過程の研究

    2014 - 2016

    科学研究費補助金  基盤研究(C)

    相木 秀則

  7. 非静力大気海洋結合モデルを用いた台風等の数値的研究

    2011 - 2012

    科学研究費補助金  新学術 公募研究

    相木 秀則

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    雲解像大気モデル(CreSS:Croud Resolving Storm Simulator:名古屋大学)と非静力海洋モデル(NHOES:Nonhydrostatic Ocean model for the Earth Simulator:海洋研究開発機構)の結合モデルをベースにしてモデル開発を進めた.従来の結合モデルでは大気海洋間の各種フラックス(風応力や熱フラックス)が単純なバルク式によって見積もられ、海面の波浪の砕波などの情報が考慮されていなかった。そこで新たに波浪モデルをコーディングして大気・海洋・波浪の(三者)結合モデルを開発した.これによって大気海洋間のフラックスを見積もるバルク式に波齢や海面粗度依存性を導入し高度化していくためのプラットフォームが完成した.波浪による摩擦によって台風が弱化されることはしばしば指摘されていたが、これをモデル感度実験を用いて確かめたり、大気境界層内の乱流収支を計算したり、運動量の収支を「風から波浪」に行く分をまず計算しその後「波浪から海流」に行く分を計算する等、さまざまなプロセスについて今後の発展が期待される,波浪の影響を取り入れることによる海洋混合層の力学の変化についてまとめた論文(Aiki&Greatbatch,2012 JPO)を出版した.モデル開発と平行して、海洋混合層が台風の発達に与える影響を調べた季節感度実験、インド洋の船舶観測(CINDY2011/DYNAMO)に合わせた毎日の予報実験(2011.10.01から2012.01.31まで)等を行った.

  8. The energetics and vertical structure of the Antarctic Circumpolar Currents and equatorial currents : a set of analyses based on a unified framework

    2009 - 2011

    Grant-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists(B)

  9. 海洋内部の渦形状抵抗の解析とインド太平洋域の中深層循環のモデリング研究

    2007 - 2008

    科学研究費補助金  日本学術振興会海外特別研究員

    相木 秀則

  10. 海洋の中層孤立渦の連続生成に関する研究

    1998 - 2001

    科学研究費補助金  日本学術振興会 特別研究員DC1

    相木 秀則

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Teaching Experience (On-campus) 3

  1. Geophysical Fluid Dynamics

    2018

  2. Physical Oceanography

    2018

  3. physical oceanography

    2016

Teaching Experience (Off-campus) 2

  1. 海洋科学

    2014.4 - 2015.3 Tokyo Gakugei University)

  2. 海洋科学

    2012.4 - 2013.3 Tokyo Gakugei University)

 

Social Contribution 3

  1. 海を観る・地球を知る2021オンライン

    Role(s):Lecturer

    蒲郡市生命の海科学館  講演会「回転水槽実験から学ぶ大気と海洋の流れの仕組み」  2021.3

  2. 海を観る・地球を知る ~体験!海洋研究最前線 in 蒲郡~

    Role(s):Planner, Demonstrator

    蒲郡市生命の海科学館・名古屋大学宇宙地球環境研究所  2019.3

     More details

    Audience: Schoolchildren, Junior students, High school students, Guardians, General

    Type:Visiting lecture

  3. 海を観る・地球を知る ~体験!海洋研究最前線 in 蒲郡~

    Role(s):Planner, Demonstrator

    蒲郡市生命の海科学館・名古屋大学宇宙地球環境研究所  2018.3

     More details

    Audience: Schoolchildren, Junior students, High school students, Guardians, General

    Type:University open house