Monitoring The Changes Of Antarctic Blue Ice And Supraglacial Lakes Using Multiple-Source Remote Sensing Data

While the global warming and sea level rise have been more concerned,global environmental changes are increased noticed by world.As an important part of the climate system,the snow and ice changes in Antarctica are also attracting people's more attention.Blue ice and supraglacial lakes are special ground features of Antarctica and are sensitive to climate change.It directly affects the dynamic changes of blue ice and supraglacial lakes through energy transfer between ice-air-water interfaces which have a crucial influence on the regional environment,even the global climate.Due to the special geographical position and harsh natural environment of Antarctica,the researches about dynamic changes of Antarctica are restricted.The development of satellite remote sensing technology has provided new methods and technologies for polar scientific research.Combined with multi-source remote sensing data the classification and distribution of Antarctic blue ice have been completed and the dynamic changes of blue ice and supraglacial lakes have been monitored.This paper makes use of multiple-source optical remote sensing data and meteorological data to monitor the long-term dynamic changes of blue ice and supraglacial lakes in key experimental regions of Antarctica,and execute the classification of the overall Antarctic blue ice.(1)Mapping and classifying blue ice areas in Antarctica based on MOA2009.The blue ice areas(BIAs)of the whole Antarctica are extracted and classified using the surface morphology image and the snow grain size image of the MOA2009 image.The classification method is based on the blue ice formation mechanism and the results are divided into two types:wind-induced blue-ice and melt-induced blue-ice.The results estimated the total area of the Antarctic BIAs occupy 253224 ± 50645 km2,contained with 121373 ± 24275 km2 wind-induced blue-ice and 131851 ± 26370 km2 melt-induced blue-ice.Their spatial distribution characteristics in Antarctica were analyzed combined the ice velocity data,digital elevation model(DEM)and ERA-Interim wind data.(2)Monitoring the long time-series change of the typical blue ice region of the East Antarctica.Comprehensive use of Landsat imagery and ERA-Interim reanalysis data to extract the blue ice areas of the Grove Mountains,Yamato Mountains,Belgica Mountains and Lecky Mountains in the East Antarctica,the long-term variations of the results between 1973 and 2016 have been analyzed.We also use MODIS data to conduct a systematic analysis of the seasonal changes of blue ice areas in the Yamato Mountains in 2002,2006,and 2012.The exposed area of blue ice in each region showed a certain decreasing trend in the observation periods,but with differences in the rate in different regions.(3)Monitoring the changes of supraglacial lakes in typical glacier around Zhongshan Station.Combined the Landsat and ASTER data to investigated the supraglacial lakes in the Polar Record Glacier for a long period of time,and monitoring the inter-annual and seasonal variations.The observations about supraglacial lakes include area,depth,and volume.Temperature data from Zhongshan Station and ALOS DEM are used to acquire the relationship among supraglacial lakes?temperature and altitude.The results show that the supraglacial lakes in the Polar Record Glacier appeared at the beginning of the melting season in mid-November of each year,and then entered the rapid growth stage,peaking in the middle and late January of the following year.The area,depth,and volume of supraglacial lakes all show good consistency,indicating that there is a clear positive correlation between these parameters.The temperature data shows that changes in the supraglacial lakes are closely related to the Positive Degree Days(PDDs).Most of the supraglacial lakes are located in the region where the elevation is less than 200m and are easily formed at the convergence of ice flow lines or region with dense ice flow lines.The characteristics of supraglacial lakes changes are related to lake types,geographical latitudes,and elevations.The mechanisms of change of different supraglacial lakes are also exit differences.