Spatial And Temporal Variations In The Elevation And Mass Of The Antarctic Ice Sheet Were Studied By Altimetry And Gravity Satellites

The Antarctic climate change is closely related to the overall change of the global climate.The Antarctic ice sheet elevation and mass change is an important indicator of the magnitude and characteristics of the Antarctic climate change.The melting and loss of the Antarctic ice sheet will directly lead to the rise of global sea level,and violently affecting the development of global production and life,According to statistics,for every 360 Gt of Antarctic ice mass loss,the global sea level will rise by about 1mm,which shows its important impact on the global climate.Altimeter and gravity satellites represent two important remote sensing tools in polar research.The altimeter satellite can directly measure the centimeter-level surface elevation data of the surface of the Antarctic ice sheet.By comparing the altimetry data for different years,the change of the ice sheet elevation with time series can be obtained.The gravity satellite can obtain the change of the mass of the surface of the earth,and then can be converted into the equivalent water column height(EWH)for gravity observation.Therefore,in the observation of the Antarctic ice sheet change,the altimetry satellite and the gravity satellite can be combined to give full play to their respective advantages and jointly carry out analysis and research on the Antarctic ice sheet change.Thanks to its dense satellite sub-satellite trajectory in the high latitudes of the Antarctic,the altimeter satellite represented by CryoSat-2 was applied to the study of special parts of the Antarctic.In the study area,the Antarctic peninsula area,the inland area of west Antarctica and DomeA were selected.In addition,considering that the digital elevation model plays an important role in various fields in the Antarctic region,this paper uses the CryoSat-2data to construct the digital elevation model in the Antarctic region.After conducting research on the above two aspects,the temporal and spatial laws of local and global ice sheet changes in Antarctica are analyzed,and the following research results are mainly obtained.1.Glaciers in the Antarctic peninsula region as a whole are in a trend of accelerated melting and migration.Of the 20 glaciers in the study area,15 showed a trend of accelerated melting or migration,while only 5 showed a cumulative trend.2.There were two different characteristics of ice sheet elevation changes in inland west Antarctica and DomeA.In general,there was no significant trend of ice sheet elevation changes over time in the two study areas.The average annual change of the ice sheet inwest Antarctica from 2011 to 2018 was 0.046 m,in which the ice sheet was accumulated from 2011 to 2013,and the mass of the ice sheet was melted or migrated from 2013 to2015.After 2015,the entire study area showed the characteristics of ice sheet accumulation.The average annual change of ice sheet elevation in ice DomeA from 2011 to 2018 was-0.0024 m.Before 2014,DomeA showed the feature of accumulation-melt,while after2014,the ice sheet mass in DomeA showed obvious signs of ablation.In the low latitude region of DomeA,the characteristics of ice sheet ablation-melt were more complex.3.The latest digital elevation model CryoSat-2 DEM for all Antarctica was established by using CryoSat-2 satellite data,and its elevation accuracy was evaluated by using ICESat data and IceBridge data.It was found that its elevation accuracy was 10.88 m in the area north of 88°S,which was better than that of RAMP V2 DEM and ERS-1 5km DEM.4.According to the study on the change of the equivalent water height column on the Antarctic surface by GRACE satellite,it is found that the mass loss of the Antarctic ice sheet is the most serious in Marie Byrd Land area in the West Antarctica region,while the accumulation of the ice sheet mass mainly occurs in the Enderby Land and Queen Maud Land in the East Antarctica region region.Through basin analysis,the equivalent water column height change and ice sheet mass change of each basin were obtained.It was found that 19 of the 27 basins in Antarctica had ice sheet mass melting or migration,and the basins with large variation range were mainly located in west Antarctica.From 2003 to2016,the annual ice sheet mass change in west Antarctica was-118.95±7.50 Gt,the annual ice sheet mass change in east Antarctica was 2.76±19.02 Gt,and the total annual ice sheet mass change in Antarctica was-106.97 12.86 Gt.The melting of the Antarctic ice sheet each year causes a global sea level rise of 0.33 mm,which accounts for 9.71% of the current global annual sea level rise,exceeding the previous growth rate of about 8%.5.After EEMD,five different driving factors for the mass change of the Antarctic ice sheet were finally extracted.The most influential factors are large-scale and long-term global climatic drivers(IMF6 and RES).In addition,seasonal drivers with a cycle of about half a year and one year,drivers of El nino-LA Nina with a cycle of 7.45 years,extremely weak hidden drivers with a cycle of 2.56 years,and abrupt drivers with a cycle of 2.75 months are included.