The Antarctic Bottom Water formation site Vincennes Bay,East Antarctica is experiencing a substantial intrusion of modified Circumpolar Deep Water(mCDW),which may inhibit the formation of Dense Shelf Water(DSW)and dri...The Antarctic Bottom Water formation site Vincennes Bay,East Antarctica is experiencing a substantial intrusion of modified Circumpolar Deep Water(mCDW),which may inhibit the formation of Dense Shelf Water(DSW)and drive basal melting of the ice shelves.Based on hydrographic data obtained from March to November in 2012,we evaluated the spatial spread of mCDW over the continental shelf region of Vincennes Bay and the associated temporal evolution of water properties,as well as the sea ice formation effect on water column in the coastal polynya.Results show that two branches of mCDW occupied the deep layers of the continental shelf,distinguished by the potential density(smaller than 27.8 kg/m^(3) or not)when potential temperatureθ=0.5°C in theθ-salinity space.The warmer and less dense branch observed on the east plateau,accessed the eastern ice shelves in the coastal polynya to drive basal melting of ice shelves.In contrast,the other colder and denser branch in the mid-depression reached the western Underwood Ice Shelf.DSW formation was detectable in the coastal polynya during September-November,proving the occurrence of deep convection.Surface heat loss and brine rejection during the intensive sea ice formation contributed to the destratification of the water column in the coastal polynya.It was estimated that at least 1.11±0.79 TW heat carried by mCDW into the inner part of the polynya.展开更多
Hydrographic observations collected by conductivity-temperature-depth（CTD） and instrumented elephant seals on the Prydz Bay continental shelf during 2012 and 2013 are used to characterize the intrusion of modified c...Hydrographic observations collected by conductivity-temperature-depth（CTD） and instrumented elephant seals on the Prydz Bay continental shelf during 2012 and 2013 are used to characterize the intrusion of modified circumpolar deep water.As a regular occurrence,modified circumpolar deep water（MCDW） intrudes onto the shelf mainly between 150–300 m layer of 73°–75°E and then turns southeast affected by the cyclonic gyre of the Prydz Bay.The southernmost point of the warm water signal is captured on the east front of Amery Ice Shelf during March 2012.In terms of vertical distribution,MCDW occupies the central layer of 200 m with about 100 m thickness in the austral summer,but when to winter transition,the layer of MCDW deepens with time on the central shelf.展开更多
Antarctica’s marginal seas are of great importance to atmosphere-ocean-ice interactions and are sensitive to global climate change.Multiple factors account for the freshwater budget in these regions,including glacier...Antarctica’s marginal seas are of great importance to atmosphere-ocean-ice interactions and are sensitive to global climate change.Multiple factors account for the freshwater budget in these regions,including glacier melting,seasonal formation/decay of sea ice,and precipitation.Hydrogen(H)and oxygen(O)isotopes represent useful proxies for determining the distribution and migration of water masses.We analyzed the H and O isotopic compositions of 190 seawater samples collected from the Amundsen Sea during the 34th Chinese Antarctic Research Expedition in 2017/2018.The upper-oceanic structure(<400 m)and freshwater(meteoric water and sea ice melt)distribution in the Amundsen Sea were identified based on conductivity-temperature-depth data and the H and O isotopic composition.Antarctic Surface Water,characterized as cold and fresh with low H and O isotopic ratios,was found distributed mainly in the upper~150 m between the Antarctic Slope Front and Polar Front,where it had been affected considerably by upwelled Upper Circumpolar Deep Water(UCDW)between 68°S and 71°S.A three-endmember(meteoric water,sea ice melt,and Circumpolar Deep Water)mixing model indicated that waters with relatively high proportions(>3%)of freshwater generally lie in the upper~50 m and extend from Antarctica to~65°S in the meridional direction(anomalously low freshwater proportion occurred between 68°S and 71°S).Winter Water mainly occupied the layer between 50 and 150 m south of 71°S in the western Amundsen Sea.The water structure and spatial distribution of freshwater in the upper Amundsen Sea were found influenced mainly by the rates of basal and surficial melting of ice shelves,seasonal alternation of sea ice melt/formation,wind forcing,and regional bathymetry.Owing to the distance between heavy sea ice boundary(HSIB)and ice shelves is much shorter in the western HSIB than the east HSIB,the western part of the heavy sea ice boundary includes a higher proportion of freshwater than the eastern region.This study,which highlighted the distribution and extent of freshwater derived from ice(ice shelves and sea ice)melt,provides important evidence that the offshore drift pathway of cold and fresh Antarctic continental shelf water is likely interrupted by upwelled UCDW in the Amundsen Sea.展开更多
近几十年来较暖的绕极深层水(Circumpolar Deep Water,CDW)不断入侵阿蒙森海陆架,使冰架底部融化,导致阿蒙森海冰架质量不断损失。分析CDW入侵阿蒙森海陆架的路径及性质变化,对研究冰架变薄和接地线后退具有重要意义。基于GLORYS12V1[Gl...近几十年来较暖的绕极深层水(Circumpolar Deep Water,CDW)不断入侵阿蒙森海陆架,使冰架底部融化,导致阿蒙森海冰架质量不断损失。分析CDW入侵阿蒙森海陆架的路径及性质变化,对研究冰架变薄和接地线后退具有重要意义。基于GLORYS12V1[Global Ocean(1/12)°Physical Reanalysis]再分析数据,对阿蒙森海西侧、中央、东侧通道的体积输运和热输运进行了计算,给出了陆架上CDW温度和盐度的变化特征,并分析了它们与流场间的关系。结果表明,Dotson-Getz海槽内的CDW主要源自西侧通道,Pine Island海槽内的CDW主要源自中央通道和东侧通道。由东侧通道入侵的CDW温度最高,西侧入侵的CDW温度最低。CDW通过西侧通道入侵陆架的体积输运和热输运在时间序列上呈现微弱的上升趋势。CDW通过中央通道向Pine Island海槽的体积输运和热输运约是东侧通道的2倍。CDW进入海槽时的温度主要受两方面影响,一方面与入侵陆架时的温度有关,一方面又被后续的混合过程所控制。展开更多
基金Supported by the National Natural Science Foundation of China(No.42130402)the International Science and Technology Cooperation Key Special Project of the National Key Research and Development Program of China(No.2023YFE0104500)。
文摘The Antarctic Bottom Water formation site Vincennes Bay,East Antarctica is experiencing a substantial intrusion of modified Circumpolar Deep Water(mCDW),which may inhibit the formation of Dense Shelf Water(DSW)and drive basal melting of the ice shelves.Based on hydrographic data obtained from March to November in 2012,we evaluated the spatial spread of mCDW over the continental shelf region of Vincennes Bay and the associated temporal evolution of water properties,as well as the sea ice formation effect on water column in the coastal polynya.Results show that two branches of mCDW occupied the deep layers of the continental shelf,distinguished by the potential density(smaller than 27.8 kg/m^(3) or not)when potential temperatureθ=0.5°C in theθ-salinity space.The warmer and less dense branch observed on the east plateau,accessed the eastern ice shelves in the coastal polynya to drive basal melting of ice shelves.In contrast,the other colder and denser branch in the mid-depression reached the western Underwood Ice Shelf.DSW formation was detectable in the coastal polynya during September-November,proving the occurrence of deep convection.Surface heat loss and brine rejection during the intensive sea ice formation contributed to the destratification of the water column in the coastal polynya.It was estimated that at least 1.11±0.79 TW heat carried by mCDW into the inner part of the polynya.
基金The Chinese Polar Science and Strategic Research Fond Project under contract No.20140307the Basic Research Operating Funds of the First Institute of Oceanography,State Oceanic Administration under contract Nos 2014T02 and 2014G02+2 种基金the China Polar Science and Strategy Research Foundation under contract No.20150102the Public Science and Technology Research Funds Projects of Ocean under contract No.201405031the National High Technology Research and Development Program(863 Program)of China under contract No.2011AA090401
文摘Hydrographic observations collected by conductivity-temperature-depth（CTD） and instrumented elephant seals on the Prydz Bay continental shelf during 2012 and 2013 are used to characterize the intrusion of modified circumpolar deep water.As a regular occurrence,modified circumpolar deep water（MCDW） intrudes onto the shelf mainly between 150–300 m layer of 73°–75°E and then turns southeast affected by the cyclonic gyre of the Prydz Bay.The southernmost point of the warm water signal is captured on the east front of Amery Ice Shelf during March 2012.In terms of vertical distribution,MCDW occupies the central layer of 200 m with about 100 m thickness in the austral summer,but when to winter transition,the layer of MCDW deepens with time on the central shelf.
基金supported by the Natural Science Foundation of China(Grant no.41806229)the Ministry of Natural Resources of the People’s Republic of China(Impact and Response of Antarctic Seas to Climate Change,Grant no.IRASCC 02-04-01).
文摘Antarctica’s marginal seas are of great importance to atmosphere-ocean-ice interactions and are sensitive to global climate change.Multiple factors account for the freshwater budget in these regions,including glacier melting,seasonal formation/decay of sea ice,and precipitation.Hydrogen(H)and oxygen(O)isotopes represent useful proxies for determining the distribution and migration of water masses.We analyzed the H and O isotopic compositions of 190 seawater samples collected from the Amundsen Sea during the 34th Chinese Antarctic Research Expedition in 2017/2018.The upper-oceanic structure(<400 m)and freshwater(meteoric water and sea ice melt)distribution in the Amundsen Sea were identified based on conductivity-temperature-depth data and the H and O isotopic composition.Antarctic Surface Water,characterized as cold and fresh with low H and O isotopic ratios,was found distributed mainly in the upper~150 m between the Antarctic Slope Front and Polar Front,where it had been affected considerably by upwelled Upper Circumpolar Deep Water(UCDW)between 68°S and 71°S.A three-endmember(meteoric water,sea ice melt,and Circumpolar Deep Water)mixing model indicated that waters with relatively high proportions(>3%)of freshwater generally lie in the upper~50 m and extend from Antarctica to~65°S in the meridional direction(anomalously low freshwater proportion occurred between 68°S and 71°S).Winter Water mainly occupied the layer between 50 and 150 m south of 71°S in the western Amundsen Sea.The water structure and spatial distribution of freshwater in the upper Amundsen Sea were found influenced mainly by the rates of basal and surficial melting of ice shelves,seasonal alternation of sea ice melt/formation,wind forcing,and regional bathymetry.Owing to the distance between heavy sea ice boundary(HSIB)and ice shelves is much shorter in the western HSIB than the east HSIB,the western part of the heavy sea ice boundary includes a higher proportion of freshwater than the eastern region.This study,which highlighted the distribution and extent of freshwater derived from ice(ice shelves and sea ice)melt,provides important evidence that the offshore drift pathway of cold and fresh Antarctic continental shelf water is likely interrupted by upwelled UCDW in the Amundsen Sea.
