The three-dimensional structure and the seasonal variation of the North Pacific meridional overturning circulation （NPMOC） are analyzed based on the Simple Ocean Data Assimilation data and Argo profiling float data....The three-dimensional structure and the seasonal variation of the North Pacific meridional overturning circulation （NPMOC） are analyzed based on the Simple Ocean Data Assimilation data and Argo profiling float data. The NPMOC displays a multi-cell structure with four cells in the North Pacific altogether. The TC and the STC are a strong clockwise meridional cell in the low latitude ocean and a weaker clockwise meridional cell between 7°N and 18°N, respectively, while the DTC and the subpolar cell are a weaker anticlockwise meridional cell between 3°N and 15°N and a weakest anticlockwise meridional cell between 35°N and 50°N, respectively. The DTC, the TC and the STC are all of very strong seasonal variations. As to the DTC, the southward transport is strongest in fall and weakest in spring. For the TC, the northward transport is strongest in winter and weakest in spring, while the southward transport is strongest in fall and weakest in spring, which is associated with the strong southward fiow of the DTC in fall. As the STC, the northward transport is strongest in winter and weakest in summer, while the southward transport is strongest in summer and weakest in spring. This seasonal difference may be associated with the DTC. The zonal wind stress and the east-west slope of sea level play important roles in the seasonal variations of the TC, the STC and the DTC.展开更多
The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years ...The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years (1987-1996). It is shown that the shallow meridional overturning circulation has a prominent seasonal reversal characteristic. In winter, the flow is northward in the upper layer and returns southward at great depth. In summer, the deep northward inflow upwells north of the equator and returns southward in the Ekman layer. In the annual mean, the northward inflow returns through two branches: one is a southward flow in the Ekman layer, the other is a flow that sinks near 10°N and returns southward between 500 m and 1000 m. There is significant interannual variability in the shallow meridional overturning circulation, with a stronger (weaker) one in 1989 (1991) and with a period of about four years. The interannual variability of the shallow meridional overturning circulation is intimately r展开更多
The large-scale upper circulations and merid-ional overturning in the upper layer of the South China Sea (SCS) with idealized bottom topography in winter and sum-mer are investigated. Simulations with the GFDL general...The large-scale upper circulations and merid-ional overturning in the upper layer of the South China Sea (SCS) with idealized bottom topography in winter and sum-mer are investigated. Simulations with the GFDL general circulation model are carried out under the conditions of open or enclosed boundary regarding transport in the Luzon Strait. The intrusion area of Kuroshio, its impact on the me-ridional overturning in the upper layer of the SCS and sea-sonal characteristic of this impact are explored, respectively. The model is forced by climatological wind stress and relaxed to monthly mean climatological temperature and salinity. The resultant meridional overturning is non-enclosed, with transporting from north to south in the surface and return-ing to north at the depth of about 500 m in winter, about 200 m in summer, with amplitudes of 105 m3/s. It shows the transporting path of intermediate water of the SCS and of-fers an idealized reference for further study on dynamics of wind-driven and thermohaline circulation of the SCS.展开更多
使用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG/IAP)开发的第三代气候海洋模式(LASG/IAP Climate system Ocean Model version 3,LICOM3.0)低分辨率版本在海洋模式比较计划(Ocean Model Intercompari...使用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG/IAP)开发的第三代气候海洋模式(LASG/IAP Climate system Ocean Model version 3,LICOM3.0)低分辨率版本在海洋模式比较计划(Ocean Model Intercomparison Project,OMIP)试验中的模拟数据,描述了南极绕极流(Antarctic Circumpolar Current,ACC)和南大洋经向翻转环流(Meridional Overturning Circulation,MOC)在1958-2009年的平均状态及其变化,并与已有的模式模拟结果和观测结果对比以评估LICOM模式的模拟效果.通过对比已有模式模拟数据发现,LICOM3.0模式模拟的ACC和南大洋MOC在两组OMIP试验中平均状态相仿、结果在合理范围内,但OMIP1试验中海表强迫的变化趋势较OMIP2试验中的变化更大,得到的环流输送在OMIP1试验中增长趋势也更大.展开更多
The global diapycnal transport in the ocean interior is one of the significant branches to return the deep water back toward near-surface. However, the amount of the diapycnal transport and the seasonal variations are...The global diapycnal transport in the ocean interior is one of the significant branches to return the deep water back toward near-surface. However, the amount of the diapycnal transport and the seasonal variations are not determined yet. This paper estimates the dissipation rate and the associated diapycnal transports at 500 m, 750 m and 1 000 m depth throughout the global ocean from the wide-spread Argo profiles, using the finescale parameterizations and classic advection-diff usion balance. The net upwelling is ~5.2±0.81 Sv (Sverdrup) which is approximately one fifth in magnitude of the formation of the deep water. The Southern Ocean is the major region with the upward diapycnal transport, while the downwelling emerges mainly in the northern North Atlantic. The upwelling in the Southern Ocean accounts for over 50% of the amount of the global summation. The seasonal cycle is obvious at 500 m and vanishes with depth, indicating the energy source at surface. The enhancement of diapycnal transport occurs at 1000min the Southern Ocean, which is pertinent with the internal wave generation due to the interaction between the robust deep-reaching flows and the rough topography. Our estimates of the diapycnal transport in the ocean interior have implications for the closure of the oceanic energy budget and the understanding of global Meridional Overturning Circulation.展开更多
Based on the 50-year Simple Ocean Data Assimilation (SODA) reanalysis data, we investigated the basic characteristics and seasonal changes of the meridional heat transport carried by the North Pacific Meridional Overt...Based on the 50-year Simple Ocean Data Assimilation (SODA) reanalysis data, we investigated the basic characteristics and seasonal changes of the meridional heat transport carried by the North Pacific Meridional Overturning Circulation. And we also examined the dynamical and thermodynamic mechanisms responsible for these heat transport variability at the seasonal time scale. Among four cells, the tropical cell (TC) is strongest with a northward heat transport (NHT) of (1.75±0.30) PW (1 PW=1.0×10^15 W) and a southward heat transport (SHT) of (-1.69±0.55) PW, the subtropical cell (STC) is second with a NHT of (0.71±0.65) PW and SHT of (-0.63±0.53) PW, the deep tropical cell (DTC) is third with a NHT of (0.18±0.03) PW and SHT of (-0.18±0.11) PW, while the subpolar cell (SPC) is weakest with a NHT of (0.09±0.05) PW and SHT of (-0.07±0.09) PW. These four cells all have diff erent seasonal changes in their NHT and SHT. Of all, the TC has stronger change in its SHT than in its NHT, so do both the DTC and SPC, but the seasonal change in the STC SHT is weaker than that in its NHT. Therefore, their dynamical and thermodynamic mechanisms are diff erent each other. The local zonal wind stress and net surface heat flux are mainly responsible for the seasonal changes in the TC and STC NHTs and SPC SHT, while the local thermocline circulations and sea temperature are primarily responsible for the seasonal changes of the TC, STC and DTC SHTs and SPC NHT.展开更多
The climatologies of dissolved oxygen concentration in the ocean simulated by nine Earth system models(ESMs) from the historical emission driven experiment of CMIP5(Phase 5 of the Climate Model Intercomparison Project...The climatologies of dissolved oxygen concentration in the ocean simulated by nine Earth system models(ESMs) from the historical emission driven experiment of CMIP5(Phase 5 of the Climate Model Intercomparison Project) are quantitatively evaluated by comparing the simulated oxygen to the WOA09 observation based on common statistical metrics. At the sea surface, distribution of dissolved oxygen is well simulated by all nine ESMs due to well-simulated sea surface temperature(SST), with both globally-averaged error and root mean square error(RMSE) close to zero, and both correlation coefficients and normalized standard deviation close to 1. However, the model performance differs from each other at the intermediate depth and deep ocean where important water masses exist. At the depth of 500 to 1 000 m where the oxygen minimum zones(OMZs) exist, all ESMs show a maximum of globally-averaged error and RMSE, and a minimum of the spatial correlation coefficient. In the ocean interior, the reason for model biases is complicated, and both the meridional overturning circulation(MOC) and the particulate organic carbon flux contribute to the biases of dissolved oxygen distribution. Analysis results show the physical bias contributes more. Simulation bias of important water masses such as North Atlantic Deep Water(NADW), Antarctic Bottom Water(AABW) and North Pacific Intermediate Water(NPIW) indicated by distributions of MOCs greatly affects the distributions of oxygen in north Atlantic, Southern Ocean and north Pacific, respectively.Although the model simulations of oxygen differ greatly from each other in the ocean interior, the multi-model mean shows a better agreement with the observation.展开更多
The multi-spatial variability modes of the At-lantic Meridional Overturning Circulation (MOO are iden-tified in the natural coupled simulation of two climate models,the MOC either oscillates at decadal scales with str...The multi-spatial variability modes of the At-lantic Meridional Overturning Circulation (MOO are iden-tified in the natural coupled simulation of two climate models,the MOC either oscillates at decadal scales with strong cross-equatorial flow or fluctuates locally at interannual scaleswith weaker cross-equatorial flow. Former studies mainlyemphasize the paleo-environmental and paleo-climatic im-pacts of the meridional overturning states transition; thisanalysis indicates the existence of the multi-spatial variabilitymodes of the MOC at interannual to decadal scales. Furtheranalysis indicates that the conventionally used MOC index,which is defined as the maximum zonal mean meridionalstream-function of the North Atlantic, cannot properly de-scribe the multi-spatial variability characteristics of theMOC.展开更多
The eight main tidal constituents have been implemented in the global ocean general circulation model with approximate 1° horizontal resolution.Compared with the observation data,the patterns of the tidal amplitu...The eight main tidal constituents have been implemented in the global ocean general circulation model with approximate 1° horizontal resolution.Compared with the observation data,the patterns of the tidal amplitudes and phases had been simulated fairly well.The responses of mean circulation,temperature and salinity are further investigated in the global sense.When implementing the tidal forcing,wind-driven circulations are reduced,especially those in coastal regions.It is also found that the upper cell transport of the Atlantic meridional overturning circulation（AMOC） reduces significantly,while its deep cell transport is slightly enhanced from 9×106m3/s to 10×106 m3/s.The changes of circulations are all related to the increase of a bottom friction and a vertical viscosity due to the tidal forcing.The temperature and salinity of the model are also significantly affected by the tidal forcing through the enhanced bottom friction,mixing and the changes in mean circulation.The largest changes occur in the coastal regions,where the water is cooled and freshened.In the open ocean,the changes are divided into three layers：cooled and freshened on the surface and below 3 000 m,and warmed and salted in the middle in the open ocean.In the upper two layers,the changes are mainly caused by the enhanced mixing,as warm and salty water sinks and cold and fresh water rises;whereas in the deep layer,the enhancement of the deep overturning circulation accounts for the cold and fresh changes in the deep ocean.展开更多
基金Supported by the National Basic Research Development Program of China(973 Program)under contract Nos 2007CB816002,2007CB816005the innovative key project of Chinese Academy of Sciences under contract No.KZCXZ-YW-201
文摘The three-dimensional structure and the seasonal variation of the North Pacific meridional overturning circulation （NPMOC） are analyzed based on the Simple Ocean Data Assimilation data and Argo profiling float data. The NPMOC displays a multi-cell structure with four cells in the North Pacific altogether. The TC and the STC are a strong clockwise meridional cell in the low latitude ocean and a weaker clockwise meridional cell between 7°N and 18°N, respectively, while the DTC and the subpolar cell are a weaker anticlockwise meridional cell between 3°N and 15°N and a weakest anticlockwise meridional cell between 35°N and 50°N, respectively. The DTC, the TC and the STC are all of very strong seasonal variations. As to the DTC, the southward transport is strongest in fall and weakest in spring. For the TC, the northward transport is strongest in winter and weakest in spring, while the southward transport is strongest in fall and weakest in spring, which is associated with the strong southward fiow of the DTC in fall. As the STC, the northward transport is strongest in winter and weakest in summer, while the southward transport is strongest in summer and weakest in spring. This seasonal difference may be associated with the DTC. The zonal wind stress and the east-west slope of sea level play important roles in the seasonal variations of the TC, the STC and the DTC.
基金This study was supported by National Natural Science Foundation of China(NSFC)under Grant No.40233033.
文摘The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years (1987-1996). It is shown that the shallow meridional overturning circulation has a prominent seasonal reversal characteristic. In winter, the flow is northward in the upper layer and returns southward at great depth. In summer, the deep northward inflow upwells north of the equator and returns southward in the Ekman layer. In the annual mean, the northward inflow returns through two branches: one is a southward flow in the Ekman layer, the other is a flow that sinks near 10°N and returns southward between 500 m and 1000 m. There is significant interannual variability in the shallow meridional overturning circulation, with a stronger (weaker) one in 1989 (1991) and with a period of about four years. The interannual variability of the shallow meridional overturning circulation is intimately r
文摘The large-scale upper circulations and merid-ional overturning in the upper layer of the South China Sea (SCS) with idealized bottom topography in winter and sum-mer are investigated. Simulations with the GFDL general circulation model are carried out under the conditions of open or enclosed boundary regarding transport in the Luzon Strait. The intrusion area of Kuroshio, its impact on the me-ridional overturning in the upper layer of the SCS and sea-sonal characteristic of this impact are explored, respectively. The model is forced by climatological wind stress and relaxed to monthly mean climatological temperature and salinity. The resultant meridional overturning is non-enclosed, with transporting from north to south in the surface and return-ing to north at the depth of about 500 m in winter, about 200 m in summer, with amplitudes of 105 m3/s. It shows the transporting path of intermediate water of the SCS and of-fers an idealized reference for further study on dynamics of wind-driven and thermohaline circulation of the SCS.
文摘使用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG/IAP)开发的第三代气候海洋模式(LASG/IAP Climate system Ocean Model version 3,LICOM3.0)低分辨率版本在海洋模式比较计划(Ocean Model Intercomparison Project,OMIP)试验中的模拟数据,描述了南极绕极流(Antarctic Circumpolar Current,ACC)和南大洋经向翻转环流(Meridional Overturning Circulation,MOC)在1958-2009年的平均状态及其变化,并与已有的模式模拟结果和观测结果对比以评估LICOM模式的模拟效果.通过对比已有模式模拟数据发现,LICOM3.0模式模拟的ACC和南大洋MOC在两组OMIP试验中平均状态相仿、结果在合理范围内,但OMIP1试验中海表强迫的变化趋势较OMIP2试验中的变化更大,得到的环流输送在OMIP1试验中增长趋势也更大.
基金Supported by Qingdao Pilot National Laboratory for Marine Science and Technology(No.2018ASKJ01)the National Natural Science Foundation of China(Nos.41676168,41376028)+3 种基金the National Key Research and Development Program(Nos.2016YFC1401004,2016YFC1401008)the NSFC-Innovation Research Group of Sciences Fund(No.41421005)Aoshan S&T Innovation Project from Qingdao Pilot National Laboratory for Marine Science and Technology,the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)National Science Foundation for Young Scientists of China(No.41606200)
文摘The global diapycnal transport in the ocean interior is one of the significant branches to return the deep water back toward near-surface. However, the amount of the diapycnal transport and the seasonal variations are not determined yet. This paper estimates the dissipation rate and the associated diapycnal transports at 500 m, 750 m and 1 000 m depth throughout the global ocean from the wide-spread Argo profiles, using the finescale parameterizations and classic advection-diff usion balance. The net upwelling is ~5.2±0.81 Sv (Sverdrup) which is approximately one fifth in magnitude of the formation of the deep water. The Southern Ocean is the major region with the upward diapycnal transport, while the downwelling emerges mainly in the northern North Atlantic. The upwelling in the Southern Ocean accounts for over 50% of the amount of the global summation. The seasonal cycle is obvious at 500 m and vanishes with depth, indicating the energy source at surface. The enhancement of diapycnal transport occurs at 1000min the Southern Ocean, which is pertinent with the internal wave generation due to the interaction between the robust deep-reaching flows and the rough topography. Our estimates of the diapycnal transport in the ocean interior have implications for the closure of the oceanic energy budget and the understanding of global Meridional Overturning Circulation.
基金Supported by the National Natural Science Foundation of China(Nos.41406012,41576060)the Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics(Second Institute of Oceanography)(No.SOED1613)+1 种基金the Open Fund of Key Laboratory of Global Change and Marine-Atmospheric Chemistry,State Oceanic Administration,China(No.GCMAC1501)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)
文摘Based on the 50-year Simple Ocean Data Assimilation (SODA) reanalysis data, we investigated the basic characteristics and seasonal changes of the meridional heat transport carried by the North Pacific Meridional Overturning Circulation. And we also examined the dynamical and thermodynamic mechanisms responsible for these heat transport variability at the seasonal time scale. Among four cells, the tropical cell (TC) is strongest with a northward heat transport (NHT) of (1.75±0.30) PW (1 PW=1.0×10^15 W) and a southward heat transport (SHT) of (-1.69±0.55) PW, the subtropical cell (STC) is second with a NHT of (0.71±0.65) PW and SHT of (-0.63±0.53) PW, the deep tropical cell (DTC) is third with a NHT of (0.18±0.03) PW and SHT of (-0.18±0.11) PW, while the subpolar cell (SPC) is weakest with a NHT of (0.09±0.05) PW and SHT of (-0.07±0.09) PW. These four cells all have diff erent seasonal changes in their NHT and SHT. Of all, the TC has stronger change in its SHT than in its NHT, so do both the DTC and SPC, but the seasonal change in the STC SHT is weaker than that in its NHT. Therefore, their dynamical and thermodynamic mechanisms are diff erent each other. The local zonal wind stress and net surface heat flux are mainly responsible for the seasonal changes in the TC and STC NHTs and SPC SHT, while the local thermocline circulations and sea temperature are primarily responsible for the seasonal changes of the TC, STC and DTC SHTs and SPC NHT.
基金The National Natural Science Foundation of China under contract No.41306029the Basic Scientific Fund for National Public Research Institutes of China under contract Nos 2013T01 and 2014G25
文摘The climatologies of dissolved oxygen concentration in the ocean simulated by nine Earth system models(ESMs) from the historical emission driven experiment of CMIP5(Phase 5 of the Climate Model Intercomparison Project) are quantitatively evaluated by comparing the simulated oxygen to the WOA09 observation based on common statistical metrics. At the sea surface, distribution of dissolved oxygen is well simulated by all nine ESMs due to well-simulated sea surface temperature(SST), with both globally-averaged error and root mean square error(RMSE) close to zero, and both correlation coefficients and normalized standard deviation close to 1. However, the model performance differs from each other at the intermediate depth and deep ocean where important water masses exist. At the depth of 500 to 1 000 m where the oxygen minimum zones(OMZs) exist, all ESMs show a maximum of globally-averaged error and RMSE, and a minimum of the spatial correlation coefficient. In the ocean interior, the reason for model biases is complicated, and both the meridional overturning circulation(MOC) and the particulate organic carbon flux contribute to the biases of dissolved oxygen distribution. Analysis results show the physical bias contributes more. Simulation bias of important water masses such as North Atlantic Deep Water(NADW), Antarctic Bottom Water(AABW) and North Pacific Intermediate Water(NPIW) indicated by distributions of MOCs greatly affects the distributions of oxygen in north Atlantic, Southern Ocean and north Pacific, respectively.Although the model simulations of oxygen differ greatly from each other in the ocean interior, the multi-model mean shows a better agreement with the observation.
文摘The multi-spatial variability modes of the At-lantic Meridional Overturning Circulation (MOO are iden-tified in the natural coupled simulation of two climate models,the MOC either oscillates at decadal scales with strong cross-equatorial flow or fluctuates locally at interannual scaleswith weaker cross-equatorial flow. Former studies mainlyemphasize the paleo-environmental and paleo-climatic im-pacts of the meridional overturning states transition; thisanalysis indicates the existence of the multi-spatial variabilitymodes of the MOC at interannual to decadal scales. Furtheranalysis indicates that the conventionally used MOC index,which is defined as the maximum zonal mean meridionalstream-function of the North Atlantic, cannot properly de-scribe the multi-spatial variability characteristics of theMOC.
基金The National Key Program for Developing Basic Sciences of China under contract No.2013CB956204the National Natural Science Foundation of China under contract Nos 41275084 and 41576025the Strategic Priority Research of the Chinese Academy of Science under contract Nos XDA01020304 and DA05110302
文摘The eight main tidal constituents have been implemented in the global ocean general circulation model with approximate 1° horizontal resolution.Compared with the observation data,the patterns of the tidal amplitudes and phases had been simulated fairly well.The responses of mean circulation,temperature and salinity are further investigated in the global sense.When implementing the tidal forcing,wind-driven circulations are reduced,especially those in coastal regions.It is also found that the upper cell transport of the Atlantic meridional overturning circulation（AMOC） reduces significantly,while its deep cell transport is slightly enhanced from 9×106m3/s to 10×106 m3/s.The changes of circulations are all related to the increase of a bottom friction and a vertical viscosity due to the tidal forcing.The temperature and salinity of the model are also significantly affected by the tidal forcing through the enhanced bottom friction,mixing and the changes in mean circulation.The largest changes occur in the coastal regions,where the water is cooled and freshened.In the open ocean,the changes are divided into three layers：cooled and freshened on the surface and below 3 000 m,and warmed and salted in the middle in the open ocean.In the upper two layers,the changes are mainly caused by the enhanced mixing,as warm and salty water sinks and cold and fresh water rises;whereas in the deep layer,the enhancement of the deep overturning circulation accounts for the cold and fresh changes in the deep ocean.
