During the 10th Chinese Arctic scientific expedition carried out in the summer of 2019,the surface current in the high-latitude areas of the Arctic Ocean was observed using a self-developed surface drifting buoy,which...During the 10th Chinese Arctic scientific expedition carried out in the summer of 2019,the surface current in the high-latitude areas of the Arctic Ocean was observed using a self-developed surface drifting buoy,which was initially deployed in the Chukchi Sea.The buoy traversed the Chukchi Sea,Chukchi Abyssal Plain,Mendeleev Ridge,Makarov Basin,and Canada Basin over a period of 632 d.After returning to the Mendeleev Ridge,it continued to drift toward the pole.Overall,the track of the buoy reflected the characteristics of the transpolar drift and Chukchi Slope Current,as well as the inertial flow,cross-ridge surface flow,and even the surface disorganized flow for some time intervals.The results showed that:(1)the transpolar drift mainly occurs in the Chukchi Abyssal Plain,Mendeleev Ridge,and western Canada Basin to the east of the ridge where sea ice concentration is high,and the average northward flow velocity in the region between 79.41°N and 86.32°N was 5.1 cm/s;(2)the average surface velocity of the Chukchi Slope Current was 13.5 cm/s,and while this current moves westward along the continental slope,it also extends northwestward across the continental slope and flows to the deep sea;and(3)when sea ice concentration was less than 50%,the inertial flow was more significant(the maximum observed inertial flow was 26 cm/s,and the radius of the inertia circle was 3.6 km).展开更多
Based on an eddy permitting ocean general circulation model, the response of water masses to two distinct climate scenarios in the South Pacific is assessed in this paper. Under annually repeating atmospheric forcing ...Based on an eddy permitting ocean general circulation model, the response of water masses to two distinct climate scenarios in the South Pacific is assessed in this paper. Under annually repeating atmospheric forcing that is characterized by different westerlies and associated heat flux, the response of Subantarctic Mode Water（SAMW） and Antarctic Intermediate Water（AAIW） is quantitatively estimated. Both SAMW and AAIW are found to be warmer, saltier and denser under intensified westerlies and increased heat loss. The increase in the subduction volume of SAMW and AAIW is about 19.8 Sv（1 Sv =10-6m-3s-（-1））. The lateral induction term plays a dominant role in the changes in the subduction volume due to the deepening of the mixed layer depth（MLD）. Furthermore, analysis of the buoyancy budget is used to quantitatively diagnose the reason for the changes in the MLD. The deepening of the MLD is found to be primarily caused by the strengthening of heat loss from the ocean to the atmosphere in the formation region of SAMW and AAIW.展开更多
In recent decades,Arctic climate is warming at a rate of almost twice the global average(Osborne et al.,2018).The surface atmosphere and oceanic temperatures over Arctic Ocean increase leads to the rapid retreat of se...In recent decades,Arctic climate is warming at a rate of almost twice the global average(Osborne et al.,2018).The surface atmosphere and oceanic temperatures over Arctic Ocean increase leads to the rapid retreat of sea ice.The extension and thickness of sea ice in the Arctic,as well as the multi-year ice coverage,have decreased significantly.For example,the September sea ice extent in the Arctic,which is the end of the summer melt season,decreases at a rate of larger than 11%per decade(Polyakov et al.,2012).展开更多
The response of the mixed layer depth(MLD)and subduction rate in the subtropical Northeast Pacific to global warming is investigated based on 9 CMIP5 models.Compared with the present climate in the 9 models,the respon...The response of the mixed layer depth(MLD)and subduction rate in the subtropical Northeast Pacific to global warming is investigated based on 9 CMIP5 models.Compared with the present climate in the 9 models,the response of the MLD in the subtropical Northeast Pacific to the increased radiation forcing is spatially nonuniform,with the maximum shoaling about 50 m in the ensemble mean result.The inter-model differences of MLD change are non-negligible,which depend on the various dominated mechanisms.On the north of the MLD front,MLD shallows largely and is influenced by Ekman pumping,heat flux,and upper-ocean cold advection changes.On the south of the MLD front,MLD changes a little in the warmer climate,which is mainly due to the upper-ocean warm advection change.As a result,the MLD front intensity weakens obviously from 0.24 m/km to0.15 m/km(about 33.9%)in the ensemble mean,not only due to the maximum of MLD shoaling but also dependent on the MLD non-uniform spatial variability.The spatially non-uniform decrease of the subduction rate is primarily dominated by the lateral induction reduction(about 85%in ensemble mean)due to the significant weakening of the MLD front.This research indicates that the ocean advection change impacts the MLD spatially non-uniform change greatly,and then plays an important role in the response of the MLD front and the subduction process to global warming.展开更多
Ship-borne infrared radiometric measurements conducted during the Chinese National Arctic Research Expedition(CHINARE)in 2008,2010,2012,2014,2016 and 2017 were used for in situ validation studies of the Moderate Resol...Ship-borne infrared radiometric measurements conducted during the Chinese National Arctic Research Expedition(CHINARE)in 2008,2010,2012,2014,2016 and 2017 were used for in situ validation studies of the Moderate Resolution Imaging Spectroradiometer(MODIS)sea ice surface temperature(IST)product.Observations of sea ice were made using a KT19.85 radiometer mounted on the Chinese icebreaker Xuelong between July and September over six years.The MODIS-derived ISTs from the satellites,Terra and Aqua,both show close correspondence with ISTs derived from radiometer spot measurements averaged over areas of 4 km×4 km,spanning the temperature range of 262–280 K with a±1.7 K(Aqua)and±1.6 K(Terra)variation.The consistency of the results over each year indicates that MODIS provides a suitable platform for remotely deriving surface temperature data when the sky is clear.Investigation into factors that cause the MODIS IST bias(defined as the difference between MODIS and KT19.85 ISTs)shows that large positive bias is caused by increased coverage of leads and melt ponds,while large negative bias mostly arises from undetected clouds.Thin vapor fog forming over Arctic sea ice may explain the cold bias when cloud cover is below 20%.展开更多
基金The Fundamental Research Fund Project of the First Institute of OceanographyMinistry of Natural Resources+1 种基金under contract No.GY022Y07the National Natural Science Foundation of China under contract No.42106232。
文摘During the 10th Chinese Arctic scientific expedition carried out in the summer of 2019,the surface current in the high-latitude areas of the Arctic Ocean was observed using a self-developed surface drifting buoy,which was initially deployed in the Chukchi Sea.The buoy traversed the Chukchi Sea,Chukchi Abyssal Plain,Mendeleev Ridge,Makarov Basin,and Canada Basin over a period of 632 d.After returning to the Mendeleev Ridge,it continued to drift toward the pole.Overall,the track of the buoy reflected the characteristics of the transpolar drift and Chukchi Slope Current,as well as the inertial flow,cross-ridge surface flow,and even the surface disorganized flow for some time intervals.The results showed that:(1)the transpolar drift mainly occurs in the Chukchi Abyssal Plain,Mendeleev Ridge,and western Canada Basin to the east of the ridge where sea ice concentration is high,and the average northward flow velocity in the region between 79.41°N and 86.32°N was 5.1 cm/s;(2)the average surface velocity of the Chukchi Slope Current was 13.5 cm/s,and while this current moves westward along the continental slope,it also extends northwestward across the continental slope and flows to the deep sea;and(3)when sea ice concentration was less than 50%,the inertial flow was more significant(the maximum observed inertial flow was 26 cm/s,and the radius of the inertia circle was 3.6 km).
基金supported by the Major State Basic Research Development Program of China(Grant No.2016YFA0601804)the National Natural Science Foundation of China(Grant Nos.41306208,41276200,41406214,41376190 and 41606217)+4 种基金the scientific Research Foundation of Nanjing University of Information Science and Technology(Grant No.2015r043)the open project of the Polar Research Institute of China(Grant No.KP201301)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Jiangsu Government Scholarship for Overseas Studiesthe China Scholarship Council
文摘Based on an eddy permitting ocean general circulation model, the response of water masses to two distinct climate scenarios in the South Pacific is assessed in this paper. Under annually repeating atmospheric forcing that is characterized by different westerlies and associated heat flux, the response of Subantarctic Mode Water（SAMW） and Antarctic Intermediate Water（AAIW） is quantitatively estimated. Both SAMW and AAIW are found to be warmer, saltier and denser under intensified westerlies and increased heat loss. The increase in the subduction volume of SAMW and AAIW is about 19.8 Sv（1 Sv =10-6m-3s-（-1））. The lateral induction term plays a dominant role in the changes in the subduction volume due to the deepening of the mixed layer depth（MLD）. Furthermore, analysis of the buoyancy budget is used to quantitatively diagnose the reason for the changes in the MLD. The deepening of the MLD is found to be primarily caused by the strengthening of heat loss from the ocean to the atmosphere in the formation region of SAMW and AAIW.
基金The National Key R&D Program of China under contract No.2016YFC1402700
文摘In recent decades,Arctic climate is warming at a rate of almost twice the global average(Osborne et al.,2018).The surface atmosphere and oceanic temperatures over Arctic Ocean increase leads to the rapid retreat of sea ice.The extension and thickness of sea ice in the Arctic,as well as the multi-year ice coverage,have decreased significantly.For example,the September sea ice extent in the Arctic,which is the end of the summer melt season,decreases at a rate of larger than 11%per decade(Polyakov et al.,2012).
基金The National Natural Science Foundation of China under contract No.41606217the Open Fund of the Key Laboratory of Research on Marine Hazards Forecasting under contract No.LOMF1702+3 种基金the Open Fund of Key Laboratory for Polar Science,Polar Research Institute of ChinaMinistry of Natural Resources under contract No.KP201702the Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences under contract No.KLOCW1903the Natural Science Foundation of Jiangsu Province under contract No.BK20191405。
文摘The response of the mixed layer depth(MLD)and subduction rate in the subtropical Northeast Pacific to global warming is investigated based on 9 CMIP5 models.Compared with the present climate in the 9 models,the response of the MLD in the subtropical Northeast Pacific to the increased radiation forcing is spatially nonuniform,with the maximum shoaling about 50 m in the ensemble mean result.The inter-model differences of MLD change are non-negligible,which depend on the various dominated mechanisms.On the north of the MLD front,MLD shallows largely and is influenced by Ekman pumping,heat flux,and upper-ocean cold advection changes.On the south of the MLD front,MLD changes a little in the warmer climate,which is mainly due to the upper-ocean warm advection change.As a result,the MLD front intensity weakens obviously from 0.24 m/km to0.15 m/km(about 33.9%)in the ensemble mean,not only due to the maximum of MLD shoaling but also dependent on the MLD non-uniform spatial variability.The spatially non-uniform decrease of the subduction rate is primarily dominated by the lateral induction reduction(about 85%in ensemble mean)due to the significant weakening of the MLD front.This research indicates that the ocean advection change impacts the MLD spatially non-uniform change greatly,and then plays an important role in the response of the MLD front and the subduction process to global warming.
基金The National Natural Science Foundation of China under contract No.41606222the National Key Research and Development Project under contract No.2016YFC1400303.
文摘Ship-borne infrared radiometric measurements conducted during the Chinese National Arctic Research Expedition(CHINARE)in 2008,2010,2012,2014,2016 and 2017 were used for in situ validation studies of the Moderate Resolution Imaging Spectroradiometer(MODIS)sea ice surface temperature(IST)product.Observations of sea ice were made using a KT19.85 radiometer mounted on the Chinese icebreaker Xuelong between July and September over six years.The MODIS-derived ISTs from the satellites,Terra and Aqua,both show close correspondence with ISTs derived from radiometer spot measurements averaged over areas of 4 km×4 km,spanning the temperature range of 262–280 K with a±1.7 K(Aqua)and±1.6 K(Terra)variation.The consistency of the results over each year indicates that MODIS provides a suitable platform for remotely deriving surface temperature data when the sky is clear.Investigation into factors that cause the MODIS IST bias(defined as the difference between MODIS and KT19.85 ISTs)shows that large positive bias is caused by increased coverage of leads and melt ponds,while large negative bias mostly arises from undetected clouds.Thin vapor fog forming over Arctic sea ice may explain the cold bias when cloud cover is below 20%.
