Data Decomposition Method Of Icesat Satellite Laser Altimetry And Its Application In Ice Sheet Elevation Change

Lidar has the characteristics of direct acquisition of three-dimensional spatial information,strong anti-jamming ability and strong penetration.It is now widely used in lunar exploration,digital city,polar ice monitoring and other fields.The ICESat(Ice,Cloud,and Land Elevation Satellite)satellite launched by the United States in January 2003 is the first laser altimeter satellite in the world.It has greatly changed the situation that it was difficult for people to obtain the vertical information of the earth in the past.At the same time,in the previous polar environment monitoring,due to the harsh natural conditions and the limitations of the instrument itself,it has been unable to monitor the polar changes in an all-round way.In addition,the changes of the polar environment are related to the impact of global climate change and human life.The emergence of ICESat satellite has greatly solved this problem,because ICESat satellite monitoring is not subject to climate change,and its high orbit,wide coverage and other characteristics,has increasingly become an important means of polar environmental monitoring.Based on ICESat satellite altimetry data-GLAS full waveform data,this paper analyses and compares the different decomposition methods of GLAS full waveform data,and summarizes the advantages and disadvantages of different decomposition methods on different ground objects.At the same time,aiming at the problems of the common decomposition method of GLAS full-waveform data-Gauss decomposition method,this paper constructs the Gauss peak method based on the peak frequency histogram,and uses the fitting accuracy and the number of times to achieve the fitting accuracy as the evaluation index to measure the decomposition efficiency of the Gauss peak method and the Gauss decomposition method.In order to improve the monitoring accuracy of the elevation change in the ice sheet area,the Gauss peak method is used to estimate the slope of the ice sheet area in polar environmental monitoring.The DEM of the Antarctic PANDA section from 2003 to 2008 is established by using the full waveform data of GLAS,and the elevation change of the PANDA section is studied.Specific research contents are as follows:(1)Taking the qualitative and quantitative decomposition of the echo signals of eight typical terrain objects as an example,the decomposition effects of the commonly used Gauss decomposition and the Gauss wavelet decomposition methods are compared.The results show that the best fitting degree of the Gauss decomposition and the Gauss wavelet decomposition is the same when decomposing the terrain objects in flat areas,and the number of times of the best fitting degree is basically the same;the noise is relatively large For complex cases,the results of echo signal processing by Gauss decomposition decomposition are better than that by Gauss wavelet basis decomposition,and the number of times to achieve the best fitting is less.(2)Aiming at the problems of inaccurate estimation of the number of waveform components,high complexity of algorithm,weak applicability and susceptibility to noise in common Gauss decomposition methods,a new method based on peak frequency histogram is proposed.This method divides waveform data into two types: easy-toprocess and difficult-to-process,and gives different solutions for these two kinds of waveform data,respectively.Gauss decomposition method is used for qualitative and quantitative comparative analysis.The experimental results show that compared with the Gauss decomposition method,the Gauss peak method has higher fitting accuracy,more accurate number of decomposed waveform components,fewer fitting times and shorter running time.(3)Taking the Antarctic PANDA section as an example,the Gauss crest method is applied to the study of ice sheet elevation change.Using GLAS full waveform data from October 2003 to October 2008,data screening and slope correction based on Gauss crest method are carried out,and DEM of Antarctic PANDA section is constructed.The elevation change of PANDA section is analyzed by using intersection points.The experiment shows that most areas of PANDA section change slightly,and the accumulated ice cover on PANDA section is obvious,and the right and lower parts of the section are obvious.Ice and snow melt more.