| As an indispensable part of the earth system,the Antarctic Ice Sheet plays a very important role in the global climate change system and it is a key area for climate change research.Near-surface air temperature is one of the most basic factors in the Antarctic climate system,and its variation has a profound impact on the Antarctic Ice Sheet for itself and other regions of the world.In the context of global warming,climate changes in the Antarctica has attracted much attention.To understand the spatial pattern of near-surface air temperature over the Antarctic Ice Sheet and its possible driving mechanism,a high-precision and spatial-temporal resolution temperature data set is the essential prerequisite.Based on the near-surface air temperature data from 119 in-situ observations over the Antarctic Ice Sheet and MODIS Land Surface Temperature data,a quantitative relationship model between the surface temperature of the ice sheet and near-surface air temperature is established,and then the high-resolution(0.05°×0.05°)monthly near-surface air temperature products of the Antarctic Ice Sheet from 2000 to 2018 is generated.We analyze the spatio-temporal variations of the near-surface air temperature over the Antarctic Ice Sheet and the connection between near-surface air temperature variation and the Southern Hemisphere Annual Mode.The main conclusions are as follows:(1)The cross-validation results with meteorological observations show that the accuracy of the near-surface air temperature reconstruction dataset over the Antarctic Ice Sheet is high,and the interpretation variance exceeds 95%,the root mean square error is less than 4.2?,and the mean bias is within 2?.Meanwhile,through the comparison with ERA5 reanalysis data,the reconstruction dataset of near-surface air temperature performs a relatively larger warm deviation(>4?)at the Transantarctic Mountains?along the Ronne Ice Shelf of the West Antarctica?along the Amery Ice Shelf of the East Antarctica and the northern area of the Antarctic Peninsula,while the main glacial ridge of the East Antarctica shows a relatively larger cold deviation(<4?).In addition,the error in summer is larger and the error in spring and autumn is smaller.Among them,warm deviation is dominant in spring and summer,while cold deviation is dominant in autumn and winter.(2)The spatial distribution characteristics of the near-surface air temperature over the Antarctic Ice Sheet show that the hottest region is the Antarctic Peninsula,followed by the West Antarctica,and the coldest region is the East Antarctica,moreover,the near-surface air temperature in coastal areas is higher than that in inland areas,showing a regional distribution pattern which is generally related to the altitude.(3)The annual and seasonal near-surface air temperature over the Antarctic Ice Sheet show obvious spatial heterogeneity during 2001-2018,and the spatial distribution pattern of the near-surface air temperature trend in autumn is roughly consistent with the annual near-surface air temperature trend,showing that 30°W-5°E of the East Antarctica which from the Coasts Land to Queen Maud Land and the coast of Victoria Land are warming,while other areas of the East Antarctica and the Marie Byrd Land in the West Antarctica are getting colder.In spring,the significant increased trend mainly occurred in the plateau area of the East Antarctica,while most of the West Antarctica show a decreased trend.In winter and summer,the Antarctic Peninsula shows a warming trend,but the other regions have opposite signs between winter and summer.(4)The positive phase enhancement of the Southern Hemisphere Annual Mode has a cooling effect on the near-surface air temperature of the East Antarctica and the West Antarctica to varying degrees(except the Berkner Island and the coastal areas of the Coasts Land),while the warming effect is still dominated for the Antarctic Peninsula,showing obvious regional differences. |
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