Research On Retrieving Snow Depth In Altay Region Based On GPS And InSAR

As one of the most important elements of the global cryosphere,snow cover is an important component for predicting the global water cycle system.At the same time,snow depth must be used as input when calculating snow water equivalent.Obtaining snow depth is of great significance to regional hydrology and snowmelt runoff.The Altay region is located in the north of Xinjiang,one of the three major snow-covered areas in my country.The spring snowmelt is an important water source in the Altay region and has a significant impact on the development of agricultural irrigation and animal husbandry.At the same time,the Altay region is one of the snow-prone areas in my country.The monitoring of the depth of snow cover in the region is of great significance.This paper takes the middle section of the Kelan River in the Altay region as the research area.Based on GPS and In SAR technology,depth detection of snow cover is carried out from the point to the face of the Altay region.The main research content and research results of this article include:1.Start with GPS multi-path,introduce and analyze the relationship between multi-path effect and signal-to-noise ratio,and finally explain the basic principle and process of GPSIR(Global Positioning System Interferometric Reflectometry)inversion of snow depth;then start from the basic principle of In SAR,Part of the phase is analyzed,and finally the phase caused by the snow cover is analyzed,and the relationship model between the snow phase and the snow depth is established according to the characteristics of the radar beam propagating in the snow layer,and the error source of the acquired snow phase is analyzed.2.Aiming at the instability of LSP(Lomb-Scargle),the K-means dynamic clustering algorithm is used to improve the traditional GPS-IR algorithm.Obtained the point-like snow depth from the GPS snow test station(Altay station)in Altay area from December 2016 to May2018,and compared the traditional GPS-IR method with the improved GPS-IR inversion results.The experimental results show that: The improved GPS-IR can eliminate these gross errors to a certain extent,so that the results are in better agreement with the measured values.The Mean value is reduced from 2.46 cm to 1.91 cm,and the RMSE value is reduced from 2.92 cm to 2.69 cm.3.According to the topography of the study area and the type of land use and coverage,a suitable interference image pair covering the study area was selected.Based on the analysis of the characteristics of the local incident angle affected by the terrain change,the local incident angle was used to replace the satellite incident angle to correct the inversion results.The surface snow depth of the study area is obtained,and the results show that the area of negative and maximum snow depth decreases after correction.The snow depth inversion results show that the snow depth of 20161114-20170101 in the study area is mainly concentrated between0?30cm,the snow depth of 20161114-20170125 is mainly concentrated between 10?40cm,and the snow depth of 20170101-20170125 is mainly concentrated.Between 5 and 15 cm,the results of In SAR inversion at Altay station,GPS-IR inversion results,and actual snow depth results are verified,and the results show that the In SAR inversion results are reasonable.Finally,the inevitable errors in the inversion results are analyzed.