By introducing the wave-induced Coriolis-Stokes forcing into ageostrophic motion equation, th1 Eulerian transport is modified by the wave-induced Stokes drift. The long-term mean contributions of the Stokes transport ...By introducing the wave-induced Coriolis-Stokes forcing into ageostrophic motion equation, th1 Eulerian transport is modified by the wave-induced Stokes drift. The long-term mean contributions of the Stokes transport with remotely generated swells being included to the ageostrophic transport are analyzed using the ECMWF （European Centre for Medium-Range X,Veather Forecasts） reanalysis data. The ratio of Stokes transport to Ekman transport in north-south （N-S） direction can reach maximum of over 50% in the subtropical region. The preliminary influence of the Stokes transport on the North Pacific gyre is all year persistent, while the effect on the North Atlantic gyre is only obvious in boreal winter and early spring.展开更多
The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between ...The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between the ventilation flow vector and the motion vector of the tropical cyclone is inves- tigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropi- cal cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventila- tion flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.展开更多
The Southern Hemisphere （SH） westerly winds have intensified and shifted poleward since the 1970s and this trend is projected to sustain under future anthropogenic forcing. The influences of intensified SH westerlie...The Southern Hemisphere （SH） westerly winds have intensified and shifted poleward since the 1970s and this trend is projected to sustain under future anthropogenic forcing. The influences of intensified SH westerlies on the Antarctic coastal waters are still not clear. The variability of Antarctic Continental Shelf Bottom Water （ASBW） temperature is crucial for ice shelf basal melting and hence ice shelf mass balance in Antarctica. In order to understand the impacts of SH westerlies on the variability of ASBW temperature, atmospheric forcing in 1992 when the westerlies were weak and in 1998 with strong westerlies are used to drive a high-resolution ocean-sea ice general circulation model, MITgcm-ECCO2. Our simulated results show- that under the atmospheric forcing in 1998, the ASBW becomes warmer in most regions around Antarctica except the coastal region between 60°- 150°W, than for the case under atmospheric forcing in 1992. The warming of ASBW around Antarctica is due to the intense shoaling and warming of CDW induced by enhanced Ekman pumping as well as strengthened subpolar gyres. The strengthened subpolar gyres favor the transportation of warm water to the coast of Antarctica. The cooling of ASBW along the coast of the western Antarctic Peninsula is caused by stronger coastal currents, which bring colder water downstream from the northwest flank of the Weddell Sea.展开更多
The adjustment of the North Pacific Subtropical and Subpolar Gyres towards changes in wind stress leads to different time-scale variabilities, which plays a significant role in climate changes. Based on the Sim- ple O...The adjustment of the North Pacific Subtropical and Subpolar Gyres towards changes in wind stress leads to different time-scale variabilities, which plays a significant role in climate changes. Based on the Sim- ple Ocean Data Assimilation （SODA） and Global Ocean Data Assimilation System （GODAS） datasets, the variations of the Subtropical and Subpolar Gyres are diagnosed using ＂three-dimension Ocean Circulation Diagnostic Method＂, and established three types of index series describe the strength, meridional and depth center of the Subtropical and Subpolar Gyres. The above indices present the seasonal, interannual and in- terdecadal variabilities of the Subtropical and Subpolar Gyres, which proves well. Both the Gyres are the strongest in winter, but the Subtropical Gyre is the weakest in summer and the Subpolar Gyre is the weakest in autumn. The Subtropical Gyre moves northward from February to March, southward in October, and to the southernmost in around January, while the Subpolar Gyre moves northward in spring, southward in summer, northward again in autumn and reaching the extreme point in winter to the south. The common feature of the interannual and interdecadal variabilities is that the two gyres were weaker and to the north before 1976-1977, while they were stronger and to the south after 1976-1977. The Subpolar Gyre has made a paramount contribution to the variability on interdecadal scales. As is indicated with the Subpolar Gyre strength indices, there was an important shift from weak to strong around 1976-1977, and the correlation coefficient with the North Pacific Decadal Oscillation （PDO） indices was 0.45, which was far better than that between the Subtropical Gyre strength indices and the PDO. Tests show that influenced by small and mesoscale eddies, the magnitude of large-scale gyres strength is strongly dependent on data resolution. But seasonal interannual and interdecadal large-scale variabilities of the two gyres presented with indices is less affected by model resolution.展开更多
Based on the Simple Ocean Data Assimilation （SODA） products, we study the mean properties and variations of the Southern Hemisphere subpolar gyres （SHSGs） in this paper. The results show that the gyre strengths in...Based on the Simple Ocean Data Assimilation （SODA） products, we study the mean properties and variations of the Southern Hemisphere subpolar gyres （SHSGs） in this paper. The results show that the gyre strengths in the SODA estimates are （55.9±9.8）×108 ma/s for the Weddell Gyre （WG）, （37.0±6.4） ×106 ma/s for the Ross Gyre （RG）, and （27.5±8.2）x 106 ma/s for the Australian-Antarctic Gyre （AG）, respectively. There exists distinct connectivity between the adjacent gyres and then forms an oceanic super gyre structure in the southern subpolar oceans. And the interior exchanges are about （8.0±3.2）× 106 ma/s at around 70°E and （4.3±3.1）× 106 m3/s at around 140°E. The most pronounced variation for all three SHSGs occurs on the seasonal time scale, with generally stronger （weaker） SHSGs during austral winter （summer）. And the seasonal changes of the gyre structures show that the eastern boundary of the WG and AG extends considerably further east during winter and the interior exchange in the super gyre structure increases accordingly. The WG and RG also show significant semi-annual changes. The correlation analyses confirm that the variations of the gyre strengths are strongly correlated with the changes in the local wind forcing on the semi-annual and seasonal time scales.展开更多
The spatial position, seasonal variability and intensity of the main flow and the cyclonic circulation of the Black Sea waters along the axis of the divergence were identified. Corresponding calculations were done wit...The spatial position, seasonal variability and intensity of the main flow and the cyclonic circulation of the Black Sea waters along the axis of the divergence were identified. Corresponding calculations were done with using of the dynamic method and based on the climate data set of temperature and salinity for the surface and intermediate layers of the Black Sea. The important role of spring floods on the rivers of the northern-western Black Sea in the development of the water circulation features was shown because this river＇s water and main Black Sea current interact with the periphery of the western and eastern cyclonic circulation. This process is dominated at the western part sea surface cyclone： in spring and at eastern, in summer and autumn. The flow rate and nature of seasonal migration cyclonic centers were estimated. The results of research are based on a relatively large scale （40＇ latitude and 60＇ longitude） averaging and we have identified the main area of water divergence. Small, localized areas of convergence and divergence of flow that are presented in the Black Sea were not included into the scope of our research.展开更多
A dataset of drifting buoys from the Marine Environmental Data Service of Canada was analyzed to map surface circulation of the Pacific. More information of the surface circulation than that acquired before was report...A dataset of drifting buoys from the Marine Environmental Data Service of Canada was analyzed to map surface circulation of the Pacific. More information of the surface circulation than that acquired before was reported in this paper, showing clear and strong western boundary currents, equato- rial currents, and subtropical gyres in the North and South Pacific regions in velocity field, with a more systematic structure in the North Pacific.展开更多
为了对台风流场的复杂结构进行研究,采用二次变分方法对台风风场进行分解.首先,将台风的流场分解成最大的、不对称的涡旋流场和无旋流场;然后将不对称的涡旋流场分解成最大的对称涡旋和不对称的β涡旋对;最后,利用WRF(weather research ...为了对台风流场的复杂结构进行研究,采用二次变分方法对台风风场进行分解.首先,将台风的流场分解成最大的、不对称的涡旋流场和无旋流场;然后将不对称的涡旋流场分解成最大的对称涡旋和不对称的β涡旋对;最后,利用WRF(weather research and forcasting)模式(V2.1.2)模拟了200601号珍珠台风,并对各时次的500hPa风场用该方法进行分解,结果表明:该方法对台风的运动机理研究和实际的台风路径预测提供了有价值的信息.展开更多
基金The National Natural Science Foundation of China under contract Nos 40976005 and 40930844
文摘By introducing the wave-induced Coriolis-Stokes forcing into ageostrophic motion equation, th1 Eulerian transport is modified by the wave-induced Stokes drift. The long-term mean contributions of the Stokes transport with remotely generated swells being included to the ageostrophic transport are analyzed using the ECMWF （European Centre for Medium-Range X,Veather Forecasts） reanalysis data. The ratio of Stokes transport to Ekman transport in north-south （N-S） direction can reach maximum of over 50% in the subtropical region. The preliminary influence of the Stokes transport on the North Pacific gyre is all year persistent, while the effect on the North Atlantic gyre is only obvious in boreal winter and early spring.
基金This work is supported by the 8th Five-Year Project of Key Item Research of China under Grant 85-906-07-02-04.
文摘The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between the ventilation flow vector and the motion vector of the tropical cyclone is inves- tigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropi- cal cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventila- tion flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.
基金supported by the National Key R&D Program of China (Grant no.2016YFA0601804)supported by the Fundamental Research Funds for the Central Universities (Grant nos.2017B04814,2017B20714)
文摘The Southern Hemisphere （SH） westerly winds have intensified and shifted poleward since the 1970s and this trend is projected to sustain under future anthropogenic forcing. The influences of intensified SH westerlies on the Antarctic coastal waters are still not clear. The variability of Antarctic Continental Shelf Bottom Water （ASBW） temperature is crucial for ice shelf basal melting and hence ice shelf mass balance in Antarctica. In order to understand the impacts of SH westerlies on the variability of ASBW temperature, atmospheric forcing in 1992 when the westerlies were weak and in 1998 with strong westerlies are used to drive a high-resolution ocean-sea ice general circulation model, MITgcm-ECCO2. Our simulated results show- that under the atmospheric forcing in 1998, the ASBW becomes warmer in most regions around Antarctica except the coastal region between 60°- 150°W, than for the case under atmospheric forcing in 1992. The warming of ASBW around Antarctica is due to the intense shoaling and warming of CDW induced by enhanced Ekman pumping as well as strengthened subpolar gyres. The strengthened subpolar gyres favor the transportation of warm water to the coast of Antarctica. The cooling of ASBW along the coast of the western Antarctic Peninsula is caused by stronger coastal currents, which bring colder water downstream from the northwest flank of the Weddell Sea.
基金The National Natural Science Foundation of China under contract Nos 40976014 and 40805035the Basic Scientific Research and Operation Foundation of the Chinese Academy of Meteorological Sciences,China Meteorological Administration under contract No.2010Z003
文摘The adjustment of the North Pacific Subtropical and Subpolar Gyres towards changes in wind stress leads to different time-scale variabilities, which plays a significant role in climate changes. Based on the Sim- ple Ocean Data Assimilation （SODA） and Global Ocean Data Assimilation System （GODAS） datasets, the variations of the Subtropical and Subpolar Gyres are diagnosed using ＂three-dimension Ocean Circulation Diagnostic Method＂, and established three types of index series describe the strength, meridional and depth center of the Subtropical and Subpolar Gyres. The above indices present the seasonal, interannual and in- terdecadal variabilities of the Subtropical and Subpolar Gyres, which proves well. Both the Gyres are the strongest in winter, but the Subtropical Gyre is the weakest in summer and the Subpolar Gyre is the weakest in autumn. The Subtropical Gyre moves northward from February to March, southward in October, and to the southernmost in around January, while the Subpolar Gyre moves northward in spring, southward in summer, northward again in autumn and reaching the extreme point in winter to the south. The common feature of the interannual and interdecadal variabilities is that the two gyres were weaker and to the north before 1976-1977, while they were stronger and to the south after 1976-1977. The Subpolar Gyre has made a paramount contribution to the variability on interdecadal scales. As is indicated with the Subpolar Gyre strength indices, there was an important shift from weak to strong around 1976-1977, and the correlation coefficient with the North Pacific Decadal Oscillation （PDO） indices was 0.45, which was far better than that between the Subtropical Gyre strength indices and the PDO. Tests show that influenced by small and mesoscale eddies, the magnitude of large-scale gyres strength is strongly dependent on data resolution. But seasonal interannual and interdecadal large-scale variabilities of the two gyres presented with indices is less affected by model resolution.
基金The Shandong Provincial Natural Science Foundation,China under contract No.ZR2014DP011the National Natural Science Foundation of China under contract No.41406012+2 种基金the Basic Scientific Research Fund for National Public Institutes of China under contract No.2015G05the Chinese Polar Science Strategy Research Foundation under contract NO.20150305the Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences under contract No.KLOCAW1405
文摘Based on the Simple Ocean Data Assimilation （SODA） products, we study the mean properties and variations of the Southern Hemisphere subpolar gyres （SHSGs） in this paper. The results show that the gyre strengths in the SODA estimates are （55.9±9.8）×108 ma/s for the Weddell Gyre （WG）, （37.0±6.4） ×106 ma/s for the Ross Gyre （RG）, and （27.5±8.2）x 106 ma/s for the Australian-Antarctic Gyre （AG）, respectively. There exists distinct connectivity between the adjacent gyres and then forms an oceanic super gyre structure in the southern subpolar oceans. And the interior exchanges are about （8.0±3.2）× 106 ma/s at around 70°E and （4.3±3.1）× 106 m3/s at around 140°E. The most pronounced variation for all three SHSGs occurs on the seasonal time scale, with generally stronger （weaker） SHSGs during austral winter （summer）. And the seasonal changes of the gyre structures show that the eastern boundary of the WG and AG extends considerably further east during winter and the interior exchange in the super gyre structure increases accordingly. The WG and RG also show significant semi-annual changes. The correlation analyses confirm that the variations of the gyre strengths are strongly correlated with the changes in the local wind forcing on the semi-annual and seasonal time scales.
文摘The spatial position, seasonal variability and intensity of the main flow and the cyclonic circulation of the Black Sea waters along the axis of the divergence were identified. Corresponding calculations were done with using of the dynamic method and based on the climate data set of temperature and salinity for the surface and intermediate layers of the Black Sea. The important role of spring floods on the rivers of the northern-western Black Sea in the development of the water circulation features was shown because this river＇s water and main Black Sea current interact with the periphery of the western and eastern cyclonic circulation. This process is dominated at the western part sea surface cyclone： in spring and at eastern, in summer and autumn. The flow rate and nature of seasonal migration cyclonic centers were estimated. The results of research are based on a relatively large scale （40＇ latitude and 60＇ longitude） averaging and we have identified the main area of water divergence. Small, localized areas of convergence and divergence of flow that are presented in the Black Sea were not included into the scope of our research.
基金Supported by the NSFC (Key Program, No. 90411013)
文摘A dataset of drifting buoys from the Marine Environmental Data Service of Canada was analyzed to map surface circulation of the Pacific. More information of the surface circulation than that acquired before was reported in this paper, showing clear and strong western boundary currents, equato- rial currents, and subtropical gyres in the North and South Pacific regions in velocity field, with a more systematic structure in the North Pacific.
文摘为了对台风流场的复杂结构进行研究,采用二次变分方法对台风风场进行分解.首先,将台风的流场分解成最大的、不对称的涡旋流场和无旋流场;然后将不对称的涡旋流场分解成最大的对称涡旋和不对称的β涡旋对;最后,利用WRF(weather research and forcasting)模式(V2.1.2)模拟了200601号珍珠台风,并对各时次的500hPa风场用该方法进行分解,结果表明:该方法对台风的运动机理研究和实际的台风路径预测提供了有价值的信息.
