The heat content(HC)of water masses on the Ross Sea continental shelf plays an important role in regulating the circulations and the basal melting of the Ross Ice Shelf(RIS).Yet,the evolution of the HC on the Ross Sea...The heat content(HC)of water masses on the Ross Sea continental shelf plays an important role in regulating the circulations and the basal melting of the Ross Ice Shelf(RIS).Yet,the evolution of the HC on the Ross Sea continental shelf is still not clear due to the sparsity of observations.By employing a coupled regional ocean-sea ice-ice shelf model for the Ross Sea,this study analyzes the heat budget of water masses over the continental shelf and in the RIS cavity.According to the topographic features and the HC density,the continental shelf region is divided into 17 subdomains.The heat budget of the middle layer for every subdomain is analyzed.In addition,the heat budget for the RIS cavity is assessed for the first time.Owing to Modified Circumpolar Deep Water intrusion,water masses over the eastern shelf are warmer than over the western shelf,with the coldest water identified in the southwestern inner shelf.The horizontal heat flux mainly provides heat to the continental shelf,while the atmospheric forcing tends to warm up the ocean during the ice-melting period and cool down the ocean during the ice-freezing period.The vertical heat flux is generally upward and transports heat from the deep layer to the upper layer.In the RIS cavity,the seasonal cycle of the HC is dominated by the horizontal flux across the RIS front rather than the basal thermal forcing of the RIS.展开更多
The oceanic general circulations in the Ross Sea,where the southernmost ocean is located,play an important role in the climate system.Yet,the energy cycle of oceanic circulations in the Ross Sea is still unclear.By em...The oceanic general circulations in the Ross Sea,where the southernmost ocean is located,play an important role in the climate system.Yet,the energy cycle of oceanic circulations in the Ross Sea is still unclear.By employing an eddypermitting coupled regional ocean-sea ice-ice shelf model,this study investigates the oceanic energy cycle in the Ross Sea.Based on the Lorenz Energy Cycle framework,the spatiotemporal distributions of kinetic energy and available potential energy within the Ross Sea are quantitatively analyzed.The power pathways and magnitudes of energy conversion are also quantified.The simulated results show that the Mean Available Potential Energy(MAPE)is the largest energy reservoir of about 527.62 PJ(1 PJ=10^(15) J),followed by the Eddy Available Potential Energy(EAPE),the Mean Kinetic Energy(MKE),and the Eddy Kinetic Energy(EKE)of about 19.20 PJ,1.04 PJ,and 0.82 PJ,respectively.In the sub-ice-shelf cavity,the maximal MAPE is up to about 177.81 PJ,and the EAPE,MKE,and EKE are about 2.58 PJ,39.87 TJ(1 TJ=10^(12) J),and 23.05 TJ,respectively.The inputs to the regional energy reservoirs are mainly from the sea surface momentum and buoyancy fluxes.The baroclinic pathway plays a dominant role in the conversion of energy to EKE,both in the open ocean and in the sub-ice-shelf cavity.The energy conversion from EAPE to EKE in the open ocean and the sub-ice-shelf cavity is about 2.86 GW(1 GW=10^(9) J)and 162.18 MW(1 MW=10^(6) J),respectively.In addition,the kinetic energy is directed from EKE to MKE in the Ross Sea,and such an energy flow in the barotropic pathway is opposite from that in the Southern Ocean.展开更多
The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting t...The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting two simulations that include and exclude the OSC in the calculation of the ice-ocean stress(IOS), using an eddy-permitting coupled ocean-sea ice global model. By comparing the results of these two experiments, significant increases of 5%, 27%, and 24%, were found in the subpolar Southern Ocean when excluding the OSC in the IOS calculation for the ocean surface stress,upwelling, and downwelling, respectively. Excluding the OSC in the IOS calculation also visibly strengthens the total mechanical energy input to the OSC by about 16%, and increases the eddy kinetic energy and mean kinetic energy by about38% and 12%, respectively. Moreover, the response of the meridional overturning circulation in the Southern Ocean yields respective increases of about 16% and 15% for the upper and lower branches;and the subpolar gyres are also found to considerably intensify, by about 12%, 11%, and 11% in the Weddell Gyre, the Ross Gyre, and the Australian-Antarctic Gyre, respectively. The strengthened ocean circulations and Ekman pumping result in a warmer sea surface temperature(SST), and hence an incremental surface heat loss. The increased sea ice drift and warm SST lead to an expansion of the sea ice area and a reduction of sea ice volume. These results emphasize the importance of OSCs in the air-sea-ice interactions on the global ocean circulations and the mass balance of Antarctic ice shelves, and this component may become more significant as the rapid change of Antarctic sea ice.展开更多
The deterministic geophysical inversion methods are dominant when inverting magnetotelluric data whereby its results largely depends on the assumed initial model and only a single representative solution is obtained. ...The deterministic geophysical inversion methods are dominant when inverting magnetotelluric data whereby its results largely depends on the assumed initial model and only a single representative solution is obtained. A common problem to this approach is that all inversion techniques suffer from non-uniqueness since all model solutions are subjected to errors, under-determination and uncertainty. A statistical approach in nature is a possible solution to this problem as it can provide extensive information about unknown parameters. In this paper, we developed a 1D Bayesian inversion code based Metropolis-Hastings algorithm whereby the uncertainty of the earth model parameters were quantified by examining the posterior model distribution. As a test, we applied the inversion algorithm to synthetic model data obtained from available literature based on a three layer model (K, H, A and Q). The frequency for the magnetotelluric impedance data was generated from 0.01 to 100 Hz. A 5% Gaussian noise was added at each frequency in order to simulate errors to the synthetic results. The developed algorithm has been successfully applied to all types of models and results obtained have demonstrated a good compatibility with the initial synthetic model data.展开更多
The mass balance of the Antarctic Ice Sheet(AIS)is important to global sea-level change.The AIS loses mass mainly through basal melting and subsequent calving of the Antarctic ice shelves.However,the simulated basal m...The mass balance of the Antarctic Ice Sheet(AIS)is important to global sea-level change.The AIS loses mass mainly through basal melting and subsequent calving of the Antarctic ice shelves.However,the simulated basal melting rates are very uncertain in ice sheet models,partially resulting from the poor understanding of oceanic heat transports.In this article,we review the recent progress in understanding and simulating such heat transports.Regulated by major circulation features,Circumpolar Deep Water(CDW)is much closer to the Bellingshausen-Amundsen Seas and the Cooperation Sea(60°E to 90°E)and the sector further east to 160°E.The ice shelves within these sectors are experiencing enhanced basal melting resulting from tropical forcing and intensified westerlies.Around West Antarctica,the isopycnal structure favors the delivery of CDW across slopes and shelves,while around East Antarctica,the persistent and strong westward Antarctic Slope Current(Front)acts to prevent warm-water intrusion.Both eddies and troughs favor heat transport to the fronts of the ice shelves and even into the cavities.The sharp contrast between the water column thicknesses on both sides of ice shelf fronts blocks the barotropic inflows and can excite topographic Rossby waves.Inside the cavities,the heat fluxes to the bases of the ice shelves are controlled by the cavity geometry,the circulations in the cavities,and the properties of the water masses beneath the ice shelves.Limited direct observations of cavities have promoted the development of various models.To improve basal melting simulations,meltwater plume models have been developed to study meltwater-laden mixed layer dynamics by increasing the vertical resolution,with recent advanced studies considering the vertical structures of frazil ice concentration and velocity.To reduce the uncertainties in the simulated and projected basal mass loss of the Antarctic ice shelves,future efforts should be devoted to improving the bathymetry and cavity geometry,investigating small-scale processes and parameterizing these processes in coupled climate-ice sheet models,and quantifying the feedback from the mass loss of the AIS.展开更多
基金supported by the National Key R&D Program of China (Grant No. 2024YFF0506603)the Independent Research Foundation of the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant Nos. SML2023SP201 and SML2021SP306)+2 种基金the Natural Science Foundation of Guangdong Province, China (Grant No. 2024A1515012717)the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant Nos. 313021004, 313022009 and 313022001)the Program of Innovation 2030 on Smart Ocean, Zhejiang University
文摘The heat content(HC)of water masses on the Ross Sea continental shelf plays an important role in regulating the circulations and the basal melting of the Ross Ice Shelf(RIS).Yet,the evolution of the HC on the Ross Sea continental shelf is still not clear due to the sparsity of observations.By employing a coupled regional ocean-sea ice-ice shelf model for the Ross Sea,this study analyzes the heat budget of water masses over the continental shelf and in the RIS cavity.According to the topographic features and the HC density,the continental shelf region is divided into 17 subdomains.The heat budget of the middle layer for every subdomain is analyzed.In addition,the heat budget for the RIS cavity is assessed for the first time.Owing to Modified Circumpolar Deep Water intrusion,water masses over the eastern shelf are warmer than over the western shelf,with the coldest water identified in the southwestern inner shelf.The horizontal heat flux mainly provides heat to the continental shelf,while the atmospheric forcing tends to warm up the ocean during the ice-melting period and cool down the ocean during the ice-freezing period.The vertical heat flux is generally upward and transports heat from the deep layer to the upper layer.In the RIS cavity,the seasonal cycle of the HC is dominated by the horizontal flux across the RIS front rather than the basal thermal forcing of the RIS.
基金The Independent Research Foundation of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.SML2023SP201the Natural Science Foundation of Guangdong Province,China under contract No.2024A1515012717+3 种基金the Funds of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract Nos 313021004 and 313022009the National Natural Science Foundation of China under contract No.41806216the Natural Science Foundation of Jiangsu Province under contract No.BK20211015the Program of Innovation 2030 on Smart Ocean,Zhejiang University.
文摘The oceanic general circulations in the Ross Sea,where the southernmost ocean is located,play an important role in the climate system.Yet,the energy cycle of oceanic circulations in the Ross Sea is still unclear.By employing an eddypermitting coupled regional ocean-sea ice-ice shelf model,this study investigates the oceanic energy cycle in the Ross Sea.Based on the Lorenz Energy Cycle framework,the spatiotemporal distributions of kinetic energy and available potential energy within the Ross Sea are quantitatively analyzed.The power pathways and magnitudes of energy conversion are also quantified.The simulated results show that the Mean Available Potential Energy(MAPE)is the largest energy reservoir of about 527.62 PJ(1 PJ=10^(15) J),followed by the Eddy Available Potential Energy(EAPE),the Mean Kinetic Energy(MKE),and the Eddy Kinetic Energy(EKE)of about 19.20 PJ,1.04 PJ,and 0.82 PJ,respectively.In the sub-ice-shelf cavity,the maximal MAPE is up to about 177.81 PJ,and the EAPE,MKE,and EKE are about 2.58 PJ,39.87 TJ(1 TJ=10^(12) J),and 23.05 TJ,respectively.The inputs to the regional energy reservoirs are mainly from the sea surface momentum and buoyancy fluxes.The baroclinic pathway plays a dominant role in the conversion of energy to EKE,both in the open ocean and in the sub-ice-shelf cavity.The energy conversion from EAPE to EKE in the open ocean and the sub-ice-shelf cavity is about 2.86 GW(1 GW=10^(9) J)and 162.18 MW(1 MW=10^(6) J),respectively.In addition,the kinetic energy is directed from EKE to MKE in the Ross Sea,and such an energy flow in the barotropic pathway is opposite from that in the Southern Ocean.
基金supported by the Independent Research Foundation of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant No. SML2021SP306)National Natural Science Foundation of China (Grant Nos. 41941007, 41806216, 41876220, and 62177028)+2 种基金Natural Science Foundation of Jiangsu Province (Grant No. BK20211015)China Postdoctoral Science Foundation (Grant Nos. 2019T120379 and 2018M630499)the Talent start-up fund of Nanjing Xiaozhuang University (Grant No. 4172111)。
文摘The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting two simulations that include and exclude the OSC in the calculation of the ice-ocean stress(IOS), using an eddy-permitting coupled ocean-sea ice global model. By comparing the results of these two experiments, significant increases of 5%, 27%, and 24%, were found in the subpolar Southern Ocean when excluding the OSC in the IOS calculation for the ocean surface stress,upwelling, and downwelling, respectively. Excluding the OSC in the IOS calculation also visibly strengthens the total mechanical energy input to the OSC by about 16%, and increases the eddy kinetic energy and mean kinetic energy by about38% and 12%, respectively. Moreover, the response of the meridional overturning circulation in the Southern Ocean yields respective increases of about 16% and 15% for the upper and lower branches;and the subpolar gyres are also found to considerably intensify, by about 12%, 11%, and 11% in the Weddell Gyre, the Ross Gyre, and the Australian-Antarctic Gyre, respectively. The strengthened ocean circulations and Ekman pumping result in a warmer sea surface temperature(SST), and hence an incremental surface heat loss. The increased sea ice drift and warm SST lead to an expansion of the sea ice area and a reduction of sea ice volume. These results emphasize the importance of OSCs in the air-sea-ice interactions on the global ocean circulations and the mass balance of Antarctic ice shelves, and this component may become more significant as the rapid change of Antarctic sea ice.
文摘The deterministic geophysical inversion methods are dominant when inverting magnetotelluric data whereby its results largely depends on the assumed initial model and only a single representative solution is obtained. A common problem to this approach is that all inversion techniques suffer from non-uniqueness since all model solutions are subjected to errors, under-determination and uncertainty. A statistical approach in nature is a possible solution to this problem as it can provide extensive information about unknown parameters. In this paper, we developed a 1D Bayesian inversion code based Metropolis-Hastings algorithm whereby the uncertainty of the earth model parameters were quantified by examining the posterior model distribution. As a test, we applied the inversion algorithm to synthetic model data obtained from available literature based on a three layer model (K, H, A and Q). The frequency for the magnetotelluric impedance data was generated from 0.01 to 100 Hz. A 5% Gaussian noise was added at each frequency in order to simulate errors to the synthetic results. The developed algorithm has been successfully applied to all types of models and results obtained have demonstrated a good compatibility with the initial synthetic model data.
文摘The mass balance of the Antarctic Ice Sheet(AIS)is important to global sea-level change.The AIS loses mass mainly through basal melting and subsequent calving of the Antarctic ice shelves.However,the simulated basal melting rates are very uncertain in ice sheet models,partially resulting from the poor understanding of oceanic heat transports.In this article,we review the recent progress in understanding and simulating such heat transports.Regulated by major circulation features,Circumpolar Deep Water(CDW)is much closer to the Bellingshausen-Amundsen Seas and the Cooperation Sea(60°E to 90°E)and the sector further east to 160°E.The ice shelves within these sectors are experiencing enhanced basal melting resulting from tropical forcing and intensified westerlies.Around West Antarctica,the isopycnal structure favors the delivery of CDW across slopes and shelves,while around East Antarctica,the persistent and strong westward Antarctic Slope Current(Front)acts to prevent warm-water intrusion.Both eddies and troughs favor heat transport to the fronts of the ice shelves and even into the cavities.The sharp contrast between the water column thicknesses on both sides of ice shelf fronts blocks the barotropic inflows and can excite topographic Rossby waves.Inside the cavities,the heat fluxes to the bases of the ice shelves are controlled by the cavity geometry,the circulations in the cavities,and the properties of the water masses beneath the ice shelves.Limited direct observations of cavities have promoted the development of various models.To improve basal melting simulations,meltwater plume models have been developed to study meltwater-laden mixed layer dynamics by increasing the vertical resolution,with recent advanced studies considering the vertical structures of frazil ice concentration and velocity.To reduce the uncertainties in the simulated and projected basal mass loss of the Antarctic ice shelves,future efforts should be devoted to improving the bathymetry and cavity geometry,investigating small-scale processes and parameterizing these processes in coupled climate-ice sheet models,and quantifying the feedback from the mass loss of the AIS.
