Application Research Of Icebridge Airborne Altimetry In The Thwaites Glacier,West Antarctica

The Antarctica is around the South Pole,98%of which is covered by ice sheet,and the averaged ice thickness is 1.9 km?Considered as an important cold source of the global circulation system,the Antarctica influence the global climate change,while slight ice-snow variation play a vital role in the earth atmospheric circulation,thermal circulation and water circulation,that even cause the sea level rise.As one of the most active glacier in Antarctica,Thwaites Glacier(75.5°S,106.75°W)is on the Walgreen Coast of Marie Byrd Land,and flows into Pine Island Bay,part of the Amundsen Sea.In recent years,due to its vulnerability to the global warming,Thwaites Glacier flows and melts faster,and its grounding line continues retreating.Thus much attention has been paid on the Thwaites Glacier,most of the research is aimed at estimating the retreating of grounding line,the surface melting and the corresponding sea level rise.IceBridge Mission,the largest airborne survey of Earth's polar ice ever flown,have high-precision airborne altimetry data which take immence effect on the research of Thwaites Glacier.This paper analyzed the accuracy of ICESat satellite altimetry data and four widely used DEMs of Antarctica,with the IceBridge airborne altimetry data collected by ATM Lidar,while the change of surface elevation in Thwaites Glacier,west Antarctica from 2009 to 2014 is estimated,by the way of cross-point detection algorithm.The main works are as follows:1)IceBridge background,including mission statement,observation region and aircraft platforms,together with its multisource sensors that contain the mechanical structure,main function and data product and its data application were described.ICESat satellite altimetry data,and the four widely used DEMs of Antarctica,i.e.,JLB97 DEM,RAMPv2 DEM,ICESat DEM and Bamber 1km DEM were also displayed2)Based on the IceBridge airborne altimetry data collected by ATM Lidar over Thwaites Glacier,West Antarctica,the accuracy of ICESat satellite altimetry data and four widely used DEMs of Antarctica,i.e.,JLB97 DEM,RAMPv2 DEM,ICESat DEM and Bamber 1km DEM were validated and analyzed.The results show that both of ICESat satellite altimetry data and ICESat DEM feature high reliability,with a bias less than 5 m and a standard deviation less than 15 m.The reliability of Bamber 1km DEM is a bit lower than that of ICESat satellite altimetry data and ICESat DEM.The standard deviations of JLB97 DEM and RAMPv2 DEM comparing with IceBridge airborne altimetry data are larger than 30m,and the reliabilities for JLB97 DEM and RAMPv2 DEM are low especially in the sloped areas.3)Using the IceBridge airborne altimetry data collected over Thwaites Glacier,West Antarctica from 2009 to 2014,the cross points and the elevation difference of different laser operation periods were resolved,and the change of surface elevation in Thwaites Glacier,west Antarctica was estimated.The results show that the averaged elevation change of ice sheet in Thwaites Glacier,west Antarctica from 2009 to 2014 is-1.39 ±0.06 m/yr.In the costal regions,the averaged elevation change is over 1 m/yr,with a standard deviation more than 0.1 m,while in the inland regions,the corresponding elevation change is between-1 m/yr and 1 m/yr,with a standard deviation less than 0.1 m.From the point of spatial distribution,elevation change of the ice sheet is connected with the surface slope and ice velocity,in other words,the elevation changes faster where the surface slope is larger or the ice velocity is higher.