Snow Cover Dynamics Of Typical Basin In Tibetan Plateau Based On Google Earth Engine

Snow cover is an extremely significant component of the Earth's surface and is widely found in high-alpine regions.Also,it is the most active natural factor on the surface.With the background of accelerated global warming,the Tibetan Plateau is the highest area in the world at the same latitude,that is why its snow cover is most directly and obviously affected.The process of increasing snow cover and melting alternation not only has a profound impact on the overall and local climate changes,the balance of energy budgets,hydrology and water resources,but also has a profound impact on the soil environment,microbial activity,vegetation growth,and survival of animals.In addition,excessive snow has caused a series of natural disasters such as snow disasters and floods which have resulted in livestock deaths and traffic disruptions.It affects the development of economy,herders' income and living standards.Therefore,studying snow cover dynamic on the Tibetan Plateau is beneficial to reduce natural disasters,protect the ecological environment,reasonably allocate and develop water resources.This article determines the Namco and Peiku Tso watersheds as study areas in the Tibetan Plateau.We improve the snow extraction algorithm based on Google Earth Engine.And we validate the results with Landsat 7 high-resolution images.The results show that the accuracy of the improved algorithm for snow extraction is 3.1% more than MOD10A1,then we extract snow from 827 MODIS images by using our improved algorithm and obtain datasets of Peiku Tso and Namco basins.Secondly,we use Google Earth Engine's powerful cloud computing capabilities and massive data resources to process more than 300,000 GPM images,781 surface temperature images and some Landsat 7 images online and obtain datasets of annual average precipitation,surface temperature,and lake area from 2000 to 2017.Then we analyze the intra-annual and inter-annual characteristics of the snow area,the changes of the snow covered days by using the generated snow data.The results show that the spatiotemporal changes of snow cover have similarities and differences in different watershed.After analyzing the main factors of Peiku Tso and Namco basins combining temperature,precipitation and snow,we find that the water supply of Peiku Tso Lake is mainly dependent on the snow melt,and the water supply of Namco Lake is minimally affected by the snow melt.Finally,we use Java Script to carry out secondary development of Google Earth Engine and complete the snow extraction system for typical watershed in the Tibetan Plateau.The application has fast data processing speed,good visualization effect,and simple and easy-touse interface,which lowers the threshold for remote sensing data processing.And the application is beneficial to the popularization of satellite remote sensing technology and the output of related research results.