A series of numerical experiments have been conducted with a perpetual July, nine-level general circulation spectral model to determine the effect of variation of the Arctic sea ice cover extent and the joint effect o...A series of numerical experiments have been conducted with a perpetual July, nine-level general circulation spectral model to determine the effect of variation of the Arctic sea ice cover extent and the joint effect of anomalies of both the Arctic sea ice cover and the Central-eastern Equatorial Pacific sea surface temperature on the summer general circulation. Results show that the two factors,anomalously large extent of the Arctic sea ice cover and anomalously warm sea surface temperature over the Central-eastern Equatorial Pacific Ocean, play substantially the equal role in the effect on the summer general circulation, and either of them can notably induce the atmospheric anomalies. The main dynamical processes determining the effect of the Arctic sea ice and the equatorial SST anomalies are associated with two leading teleconnection patterns, i. e. the Asia North/American and Eurasian patterns observed in atmosphere. The results presented in this paper again prove that the general circulation is fundamentally motivated by the non-uniform heating between the equator and the pole on the rotating earth.展开更多
A regional Arctic configuration of the Massachusetts Institute of Technology general circulation model （MIT-gcm） is used as the coupled ice-ocean model for forecasting sea ice conditions in the Arctic Ocean at the N...A regional Arctic configuration of the Massachusetts Institute of Technology general circulation model （MIT-gcm） is used as the coupled ice-ocean model for forecasting sea ice conditions in the Arctic Ocean at the Na-tional Marine Environmental Forecasting Center of China （NMEFC）, and the numerical weather prediction from the National Center for Environmental Prediction Global Forecast System （NCEP GFS） is used as the atmospheric forcing. To improve the sea ice forecasting, a recently developed Polar Weather Research and Forecasting model （Polar WRF） model prediction is also tested as the atmospheric forcing. Their forecasting performances are evaluated with two different satellite-derived sea ice concentration products as initializa-tions： （1） the Special Sensor Microwave Imager/Sounder （SSMIS） and （2） the Advanced Microwave Scanning Radiometer for EOS （AMSR-E）. Three synoptic cases, which represent the typical atmospheric circulations over the Arctic Ocean in summer 2010, are selected to carry out the Arctic sea ice numerical forecasting experiments. The evaluations suggest that the forecasts of sea ice concentrations using the Polar WRF atmo-spheric forcing show some improvements as compared with that of the NCEP GFS.展开更多
Model studies point to enhanced warming and to increased freshwater ?uxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such ...Model studies point to enhanced warming and to increased freshwater ?uxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined e?ect of increased freshwater input to the Arctic Ocean and Arctic warming—the latter manifested as a gradual melting of the Arctic sea ice—is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runo?, and a third more extreme case, where the river runo? is ?ve times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5–2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift. Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensi?ed Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.展开更多
To assess the influence of the initial temperature field on ocean temperature and sea ice simulations,a climatological dataset(WOA18),a real-time varying dataset(SODA),and an analysis field obtained after applying the...To assess the influence of the initial temperature field on ocean temperature and sea ice simulations,a climatological dataset(WOA18),a real-time varying dataset(SODA),and an analysis field obtained after applying the“vertical projection”assimilation scheme were selected to obtain the initial temperature field(the initial moment was December 1,2015)for use in the sea ice simulation of the HAMSOM ice-ocean coupled model,considering the Bohai Sea in the 2015/2016 winter.In this study,after using this assimilation scheme,the analysis initial temperature field showed significant improvement.The simulated SST results showed that the initial temperature field had a considerable effect on the SST results in the first 45 days of the model run;after this period,the effect became negligible and the model internal dynamics and atmospheric forcing became dominant.The simulated sea ice results showed that the ice area and ice edge distance(i.e.,the distance between the intersection of the central axis and the ice edge line and axis apex)results obtained in experiment E3 which used the analysis initial temperature field were improved by~14%and~35%,respectively,and those obtained in experiment E2 which used the real-time varying initial temperature field were improved by~10%and~22%,respectively,compared to the results of experiment E1 which used the climatological initial temperature field.展开更多
文摘A series of numerical experiments have been conducted with a perpetual July, nine-level general circulation spectral model to determine the effect of variation of the Arctic sea ice cover extent and the joint effect of anomalies of both the Arctic sea ice cover and the Central-eastern Equatorial Pacific sea surface temperature on the summer general circulation. Results show that the two factors,anomalously large extent of the Arctic sea ice cover and anomalously warm sea surface temperature over the Central-eastern Equatorial Pacific Ocean, play substantially the equal role in the effect on the summer general circulation, and either of them can notably induce the atmospheric anomalies. The main dynamical processes determining the effect of the Arctic sea ice and the equatorial SST anomalies are associated with two leading teleconnection patterns, i. e. the Asia North/American and Eurasian patterns observed in atmosphere. The results presented in this paper again prove that the general circulation is fundamentally motivated by the non-uniform heating between the equator and the pole on the rotating earth.
基金The Ocean Public Welfare Project of China under contract No.201205007the National Natural Science Foundation of China under contract Nos 41176169,41376005,41376188 and 41106165
文摘A regional Arctic configuration of the Massachusetts Institute of Technology general circulation model （MIT-gcm） is used as the coupled ice-ocean model for forecasting sea ice conditions in the Arctic Ocean at the Na-tional Marine Environmental Forecasting Center of China （NMEFC）, and the numerical weather prediction from the National Center for Environmental Prediction Global Forecast System （NCEP GFS） is used as the atmospheric forcing. To improve the sea ice forecasting, a recently developed Polar Weather Research and Forecasting model （Polar WRF） model prediction is also tested as the atmospheric forcing. Their forecasting performances are evaluated with two different satellite-derived sea ice concentration products as initializa-tions： （1） the Special Sensor Microwave Imager/Sounder （SSMIS） and （2） the Advanced Microwave Scanning Radiometer for EOS （AMSR-E）. Three synoptic cases, which represent the typical atmospheric circulations over the Arctic Ocean in summer 2010, are selected to carry out the Arctic sea ice numerical forecasting experiments. The evaluations suggest that the forecasts of sea ice concentrations using the Polar WRF atmo-spheric forcing show some improvements as compared with that of the NCEP GFS.
文摘Model studies point to enhanced warming and to increased freshwater ?uxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined e?ect of increased freshwater input to the Arctic Ocean and Arctic warming—the latter manifested as a gradual melting of the Arctic sea ice—is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runo?, and a third more extreme case, where the river runo? is ?ve times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5–2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift. Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensi?ed Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.
基金This research was jointly sponsored by the National Key R&D Program of China(2019YFC 1407800)National Natural Science Foundation of China(No.42006154).
文摘To assess the influence of the initial temperature field on ocean temperature and sea ice simulations,a climatological dataset(WOA18),a real-time varying dataset(SODA),and an analysis field obtained after applying the“vertical projection”assimilation scheme were selected to obtain the initial temperature field(the initial moment was December 1,2015)for use in the sea ice simulation of the HAMSOM ice-ocean coupled model,considering the Bohai Sea in the 2015/2016 winter.In this study,after using this assimilation scheme,the analysis initial temperature field showed significant improvement.The simulated SST results showed that the initial temperature field had a considerable effect on the SST results in the first 45 days of the model run;after this period,the effect became negligible and the model internal dynamics and atmospheric forcing became dominant.The simulated sea ice results showed that the ice area and ice edge distance(i.e.,the distance between the intersection of the central axis and the ice edge line and axis apex)results obtained in experiment E3 which used the analysis initial temperature field were improved by~14%and~35%,respectively,and those obtained in experiment E2 which used the real-time varying initial temperature field were improved by~10%and~22%,respectively,compared to the results of experiment E1 which used the climatological initial temperature field.
