The annual cycle of the thickness and temperature of landfast sea ice in the East Siberian Sea has been examined using a one-dimensional thermodynamic model. The model was calibrated for the year August 2012-July 2013...The annual cycle of the thickness and temperature of landfast sea ice in the East Siberian Sea has been examined using a one-dimensional thermodynamic model. The model was calibrated for the year August 2012-July 2013, forced using the data of the Russian weather station Kotel＇ny Island and ECMWF reanalyses. Thermal growth and decay of ice were reproduced well, and the maximum annual ice thickness and breakup day became 1.64 m and the end of July. Oceanic heat flux was 2 W.m^-2 in winter and raised to 25 W.m^-2 in summer, albedo was 0.3-0.8 depending on the surface type （snow/ice and wet/dry）. The model outcome showed sensitivity to the albedo, air temperature and oceanic heat flux. The modelled snow cover was less than 10 cm having a small influence on the ice thickness. In situ sea ice thickness in the East Siberian Sea is rarely available in publications. This study provides a method for quantitative ice thickness estimation by modelling. The result can be used as a proxy to understand the sea ice conditions on the Eurasian Arctic coast, which is important for shipping and high-resolution Arctic climate modelling.展开更多
The Amery Ice Shelf is the largest ice shelf in East Antarctica. It drains continental ice from an area of more than one million square kilometres through a section of coastline that represents approximately 2% of the...The Amery Ice Shelf is the largest ice shelf in East Antarctica. It drains continental ice from an area of more than one million square kilometres through a section of coastline that represents approximately 2% of the total circumference of the Antarctic continent. In this study, we used a time series of ENVISAT ASAR images from 2004-2012 and flow lines derived from surface velocity data to monitor the changes in 12 tributaries of the Amery Ice Shelf front. The results show that the Amery Ice Shelf has been expanding and that the rates of expansion differ across the shelf. The highest average annual rate of advance from 2004-2012 was 3.36 m＇d-1 and the lowest rate was 1.65 m.d-1. The rates in 2009 and 2010 were generally lower than those in other years. There was a low correlation between the rate of expansion and the atmospheric temperature recorded at a nearby research station, however the mechanism of the relationship was complex. This study shows that the expansion of the Amery Ice Shelf is slowing down, reflecting a changing trend in climate and ice conditions in East Antarctica.展开更多
Landfast sea ice(LFSI)is a criticalcomponent of the Arctic sea ice cover,and is changing as a result of Arctic amplification of climate change.Located in coastal areas,LFSI is of great significance to the physical and...Landfast sea ice(LFSI)is a criticalcomponent of the Arctic sea ice cover,and is changing as a result of Arctic amplification of climate change.Located in coastal areas,LFSI is of great significance to the physical and ecological systems of the Arctic shelf and in local indigenous communities.We present an overview of the physics of Arctic LFSI and the associated implications on the cryosphere.LFSI is kept in place by four fastenmechanisms.The evolution of LFSI is mostly determined by thermodynamic processes,and can therefore be usedas an indicator of local climate change.We also present the dynamic processes that are active prior to the formation of LFSI,and those that are involved in LFSI freeze-up and breakup.Season length,thickness and extent of Arctic LFSI are decreasing andshowing different trends in different seas,and therefore,causing environmental and climatic impacts.An improved coordination of Arctic LFSI observation is needed with a unified and systematic observation network supported by cooperation between scientists and indigenous communities,as well as a better application of remote sensing data to acquire detailed LFSI cryosphere physical parameters,hence revolving both its annual cycle and long-term changes.Integrated investigations combining in situ measurements,satellite remote sensing and numerical modeling are needed to improve our understanding of the physical mechanisms of LFSI seasonal changes and their impacts on the environment and climate.展开更多
Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely coupled.In this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of me...Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely coupled.In this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of meteorological and sea ice conditions during the ice season of 2018-2019 relative to climatological means using a Lagrangian methodology.We obtained the anomalies along the drifting trajectories of eight sea ice mass balance buoys between the marginal ice zone and the pack ice zone in the western Arctic Ocean(~160°W-170°W and 79°N-85°N)from September 2018 toAugust 2019.The temporary collapse of the Beaufort High and a strong positive Arctic Dipole in the winter of 2018-2019 drove the three buoys in the north to drift gradually northeastward and merge into the Transpolar Drift Stream.The most prominent positive temperature anomalies in 2018-2019 along the buoy trajectories relative to 1979-2019 climatology occurred in autumn,early winter,and April,and were concentrated in the southern part of the study area;these anomalies can be partly related to the seasonal and spatial patterns of heat release from the Arctic ice-ocean system to the atmosphere.In the southern part of the study area and in autumn,the sea ice concentration in 2018-2019 was higher than that averaged over the past 10 years.However,we found no ice concentration anomalies for other regions or seasons.The sea ice thickness in the freezing season and the snow depth by the end of the winter of 2018-2019 can also be considered as normal.Although the wind speed in 2018-2019 was slightly lower than that in 1979-2019,the speed of sea ice drift and its ratio to wind speed were significantly higher than the climatology.In 2019,the sea ice surface began to melt at the end of June,which was close to the 1988-2019 climatology.However,spatial variations in the onsets ofsurface melt in 2019 differed from the climatology,and can be explained by the prevalence of a high-pressure system in the south of the Beaufort Sea in June 2019.In addition to seasonal variations,the meteorological and sea ice anomalies were influenced by spatial variations.By the end of summer 2019,the buoys had drifted to the west of the Canadian Arctic Archipelago,where the ice conditions was heavier than those at the buoy locations in early September 2018.The meteorological and sea ice anomalies identified in this study lay the foundations for subsequent analyses and simulations of sea ice mass balance based on the buoy data.展开更多
On 10 December 2017,a Chinese research vessel R/V Xuelong encountered an extensive area of landfast ice offshore Inexpressible Island(Antarctica)near the location where the fifth Chinese Antarctic research station is ...On 10 December 2017,a Chinese research vessel R/V Xuelong encountered an extensive area of landfast ice offshore Inexpressible Island(Antarctica)near the location where the fifth Chinese Antarctic research station is to be built.Using multi-source satellite images and weather data,we analyzed the ice conditions during the event season and reconstructed the development of landfast ice.Two stages in late September and early October were identified as contributing to the final ice extent.These two events are highly related to local-and large-scale weather conditions.Satellite images from 2003 to 2017 showed that four in fifteen years experienced severe landfast ice conditions,suggesting that it is not a rare phenomenon.展开更多
基金supported by research funding from the National Natural Science Foundation of China (Grant nos. 41428603, 41376186, 41476170)the EU FP7 Project Eu Ru CAS(European-Russian Centre for Cooperation in the Arctic and Sub-Arctic Environmental and Climate Research,Grant no.295068)+2 种基金Academy of Finland (Grant nos. 11409391, 259537)the Liaoning Educational Committee Foundation (Grant no. L2013497)the Ocean Public Welfare Scientific Research Project of China (Grant nos. 201205007, 201205007-2)
文摘The annual cycle of the thickness and temperature of landfast sea ice in the East Siberian Sea has been examined using a one-dimensional thermodynamic model. The model was calibrated for the year August 2012-July 2013, forced using the data of the Russian weather station Kotel＇ny Island and ECMWF reanalyses. Thermal growth and decay of ice were reproduced well, and the maximum annual ice thickness and breakup day became 1.64 m and the end of July. Oceanic heat flux was 2 W.m^-2 in winter and raised to 25 W.m^-2 in summer, albedo was 0.3-0.8 depending on the surface type （snow/ice and wet/dry）. The model outcome showed sensitivity to the albedo, air temperature and oceanic heat flux. The modelled snow cover was less than 10 cm having a small influence on the ice thickness. In situ sea ice thickness in the East Siberian Sea is rarely available in publications. This study provides a method for quantitative ice thickness estimation by modelling. The result can be used as a proxy to understand the sea ice conditions on the Eurasian Arctic coast, which is important for shipping and high-resolution Arctic climate modelling.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education (Grant no.20120003110030)the China Postdoctoral Science Foundation (Grant no.201104063)+1 种基金the Open Fund of the SOA Key Laboratory for Polar Science (Grant no.KP201101)the Fundamental Research Funds for the Central Universities (Grant no.105560GR)
文摘The Amery Ice Shelf is the largest ice shelf in East Antarctica. It drains continental ice from an area of more than one million square kilometres through a section of coastline that represents approximately 2% of the total circumference of the Antarctic continent. In this study, we used a time series of ENVISAT ASAR images from 2004-2012 and flow lines derived from surface velocity data to monitor the changes in 12 tributaries of the Amery Ice Shelf front. The results show that the Amery Ice Shelf has been expanding and that the rates of expansion differ across the shelf. The highest average annual rate of advance from 2004-2012 was 3.36 m＇d-1 and the lowest rate was 1.65 m.d-1. The rates in 2009 and 2010 were generally lower than those in other years. There was a low correlation between the rate of expansion and the atmospheric temperature recorded at a nearby research station, however the mechanism of the relationship was complex. This study shows that the expansion of the Amery Ice Shelf is slowing down, reflecting a changing trend in climate and ice conditions in East Antarctica.
基金This study was supported by the National Key Research and Development Program of China(Grant nos.2019YFC1509101 and 2017YFE0111700)the National Natural Science Foundation of China(Grant nos.41976219 and 41722605)the Academy of Finland under contract 317999.
文摘Landfast sea ice(LFSI)is a criticalcomponent of the Arctic sea ice cover,and is changing as a result of Arctic amplification of climate change.Located in coastal areas,LFSI is of great significance to the physical and ecological systems of the Arctic shelf and in local indigenous communities.We present an overview of the physics of Arctic LFSI and the associated implications on the cryosphere.LFSI is kept in place by four fastenmechanisms.The evolution of LFSI is mostly determined by thermodynamic processes,and can therefore be usedas an indicator of local climate change.We also present the dynamic processes that are active prior to the formation of LFSI,and those that are involved in LFSI freeze-up and breakup.Season length,thickness and extent of Arctic LFSI are decreasing andshowing different trends in different seas,and therefore,causing environmental and climatic impacts.An improved coordination of Arctic LFSI observation is needed with a unified and systematic observation network supported by cooperation between scientists and indigenous communities,as well as a better application of remote sensing data to acquire detailed LFSI cryosphere physical parameters,hence revolving both its annual cycle and long-term changes.Integrated investigations combining in situ measurements,satellite remote sensing and numerical modeling are needed to improve our understanding of the physical mechanisms of LFSI seasonal changes and their impacts on the environment and climate.
基金supported by grants from the National Key Research and Development Program (Grant no. 2021YFC2803304)the National Natural Science Foundation of China (Grant nos. 41976219 and 42106231)
文摘Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely coupled.In this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of meteorological and sea ice conditions during the ice season of 2018-2019 relative to climatological means using a Lagrangian methodology.We obtained the anomalies along the drifting trajectories of eight sea ice mass balance buoys between the marginal ice zone and the pack ice zone in the western Arctic Ocean(~160°W-170°W and 79°N-85°N)from September 2018 toAugust 2019.The temporary collapse of the Beaufort High and a strong positive Arctic Dipole in the winter of 2018-2019 drove the three buoys in the north to drift gradually northeastward and merge into the Transpolar Drift Stream.The most prominent positive temperature anomalies in 2018-2019 along the buoy trajectories relative to 1979-2019 climatology occurred in autumn,early winter,and April,and were concentrated in the southern part of the study area;these anomalies can be partly related to the seasonal and spatial patterns of heat release from the Arctic ice-ocean system to the atmosphere.In the southern part of the study area and in autumn,the sea ice concentration in 2018-2019 was higher than that averaged over the past 10 years.However,we found no ice concentration anomalies for other regions or seasons.The sea ice thickness in the freezing season and the snow depth by the end of the winter of 2018-2019 can also be considered as normal.Although the wind speed in 2018-2019 was slightly lower than that in 1979-2019,the speed of sea ice drift and its ratio to wind speed were significantly higher than the climatology.In 2019,the sea ice surface began to melt at the end of June,which was close to the 1988-2019 climatology.However,spatial variations in the onsets ofsurface melt in 2019 differed from the climatology,and can be explained by the prevalence of a high-pressure system in the south of the Beaufort Sea in June 2019.In addition to seasonal variations,the meteorological and sea ice anomalies were influenced by spatial variations.By the end of summer 2019,the buoys had drifted to the west of the Canadian Arctic Archipelago,where the ice conditions was heavier than those at the buoy locations in early September 2018.The meteorological and sea ice anomalies identified in this study lay the foundations for subsequent analyses and simulations of sea ice mass balance based on the buoy data.
基金supported by the National Natural Science Foundation of China (Grant nos. 41676176 and 41830536)the Open Fund of State Key Laboratory of Remote Sensing Science (Grant no. OFSLRSS201926)
文摘On 10 December 2017,a Chinese research vessel R/V Xuelong encountered an extensive area of landfast ice offshore Inexpressible Island(Antarctica)near the location where the fifth Chinese Antarctic research station is to be built.Using multi-source satellite images and weather data,we analyzed the ice conditions during the event season and reconstructed the development of landfast ice.Two stages in late September and early October were identified as contributing to the final ice extent.These two events are highly related to local-and large-scale weather conditions.Satellite images from 2003 to 2017 showed that four in fifteen years experienced severe landfast ice conditions,suggesting that it is not a rare phenomenon.
