Mass Balance Of Lambert Glacier Based On Remote Sensing Data

The cryosphere on earth can be divided into three types:terrestrial cryosphere,marine cryosphere and atmospheric cryosphere.Specifically,it is divided into polar ice sheets,ice shelves,sea ice,mountain glaciers,permafrost,and frozen water bodies in the atmosphere.Among them,the distribution of the terrestrial cryosphere is dominated by the poles and high-altitude regions of the earth,while the south and arctic regions occupy an absolute dominant position.Polar ice sheet not only contains a large amount of freshwater resources,but also has a profound impact on global climate change,water cycle and regional ecosystem.Under the background of global warming,the study of the material balance of the polar ice sheet is of great significance,which can help us to further understand the potential mass loss of the ice sheet and further evaluate the impact of the polar ice sheet on climate change.The Antarctic ice sheet has been a hotspot for research and exploration because of its huge water storage and potential impact on sea level rise.East Antarctica has four times the ice reserves of West Antarctica,so mass balance surveys for East Antarctica have been underway for decades.However,Antarctica’s vast area,large ice storage and complex ice movement have brought many difficulties to the field survey of Antarctica.At the same time,it is difficult to accurately define the input and output of ice mass.The mass balance estimates of the ice sheet have large deviations,and the development of remote sensing technology has provided a good technical means for the Antarctic survey.Remote sensing technology obtains information on the surface of a wide range of ice sheets through radar measurements and other means,realizing the possibility of obtaining data in a large range,and can survey extremely cold areas that are difficult to set foot in,solving the problem of difficult on-site measurement in some areas.The data has the characteristics of high accuracy,good continuity and clear geographic boundaries,providing a reliable data source for studying the mass balance of Antarctica.Through the combined application of various remote sensing datasets,it is possible to better analyze and explain the movement process of the ice body and the change of the mass balance of the ice sheet,so as to further understand the impact of the Antarctic ice sheet on global climate change and sea level change.The Lambert-Amery System is the largest drainage system in East Antarctica,and the Lambert Glacier is the largest glacier exporting ice volume on the Lambert-Amery System.The lower part of the Lambert Glacier is facing the mainstream area of the Amery Ice Shelf,and the upper part is the Dome A.In this dissertation,the mass balance and ice movement of Lambert Glacier are studied using the recently updated remote sensing datasets.The main contents of this article are as follows:First,on the basis of the processed basic data,this dissertation classified the main calculation elements of ice flux,and did a single data integration in a large area selected in advance.Found out the specific manifestations of ice movement in the upstream and downstream areas of Lambert,and at the same time,according to the size of the ice thickness error dataset,discussed the objective factors that need to be considered when using the data.Then compared the differences between the data in detail,selected the value range of the physical quantity that had a greater impact on the calculation result,and used the continuity of the ice velocity dataset itself on the map to select the most suitable ice gate location to ensure the ice flux calculation reliability.Then,based on the surface mass balance data RACMO2.3 and the ice gate position determined in the above steps,the glacier area of the area south of Gate1,the area between Gate1 and Gate2,and the area between Gate2 and the grounding line is first determined,and the accumulation error value of corresponding positions are calculated at the same time.Then,the surface accumulation on the three subsections was calculated separately,and the mass balance of different areas inland of the Lambert Glacier was estimated by combining the ice flux output from the glacier to the downstream through Gate1,Gate2and Gate3.Finally,this dissertation compared the mass balance results of the entire Lambert Glacier with previous studies.In the Lambert glacier area,the contribution to the ice flux downstream of Dome A about 140km downstream of the glacier is 8.5±1.9 Gt·a^-1,and the ice flux passing through the middle of the convergence area is 18.9±2.9 Gt·a^-1,the ice mass of the entire glacier entering the Amery Ice Shelf via the ground wire is 19.9±1.3 Gt·a^-1,and the ice flux output from the mainstream area of the ground wire is 19.3±1.0 Gt·a^-1.Using the annual SMB data from 1979 to 2016 of the regional atmospheric climate model RACMO2.3 as the mass input,the results of the block mass balance analysis of the upper,middle and lower regions of the Lambert Glacier show that:during November 2018 to April 2019,the central area of the glacier（about 74°S～78°S,67°E～85°E）showed a significant positive accumulation phenomenon,and the accumulation in this area was 4.1±3.5 Gt·a^-1,The net accumulation of the entire glacier was 2.4±3.5 Gt·a^-1.Although the mass balance of Lambert Glacier still shows positive accumulation,the positive accumulation in this area is decreasing compared to the early2000s.