Remote Sensing Monitoring Of Snow Cover In The Himalayas Based On Multi-source Remote Sensing Data

Located on the southern summit of the Tibetan Plateau,the Himalayas are the highest mountain ranges in the world,and their snow cover and its changes affect the regional climate,water resources and ecological environment.In order to better understand the snow cover changes in the region and overcome the problems of insufficient detailed description of low-resolution remote sensing data in the monitoring of snow cover in mountainous areas with complex terrain,the 2013-2020 Himalayan snow cover dataset was prepared by using landsat 8 clear sky conditions data with a spatial resolution of 30 m,and the relationship between snow cover days and snow cover area and climatic factors was discussed.The study can provide reference for the analysis of snow cover change in the Himalayas,the use of snowmelt water resources,the analysis of atmospheric circulation changes,and the prediction of climate evolution.The main research contents of the paper are as follows:(1)Due to the complex terrain of the Himalayas,the support vector machine classification method was selected,and the snow characteristic training samples under different terrain,shadow and other conditions were selected for snow classification.Comparing the snow cover results extracted by this method with the SNOW cover product of USGS Landsat C2,the results show that the method has better effect on snow cover in areas with complex terrain.(2)Based on high-resolution Sentinel-2 data,the results of Landsat snow extraction were verified.By creating a 900 900 m grid for comparative verification,the results show that the correlation coefficient of snow cover in the grid is above0.95,and the root mean square error is about 0.1%,and the snow discrimination results constructed by the two are well consistent.Based on this method,a snow cube with a resolution of 30 m in the Himalayas from 2013 to 2020 was constructed.(3)Based on the Landsat dataset and MODIS daily cloud-free snow cover data,the temporal and spatial dynamic analysis of snow cover in the Himalayas within 8 years was carried out from the perspective of time and space.The results show that the annual snow cover in the Himalayas peaks in February and begins to ablation period in March.The number of snow cover days is characterized by a distribution of "increasing sequentially from east to west".(4)Extract the snow cover days and cover area to analyze the relationship between snow cover changes and climatic factors in the Himalayas.The results showed that the correlations between the number of days covered and precipitation,snowfall and temperature were different.In high altitude areas,precipitation and snowfall were significantly positively correlated,and negatively correlated with temperature.The snow cover area has different correlations with different months,reaching a peak in January and a minimum in April.