Analysis Of The Spatiotemporal Characteristics Of Snow Melt Rate Based On Time-series MODIS On The Eastern Qinghai-tibet Plateau

In recent years,climate warming has led to changes in the regional environment of the Tibetan Plateau,with fluctuations in the melting of alpine snow,especially in the eastern part of the Tibetan Plateau,which has had a large impact on the watersheds of the rivers that originate in the region.As an important water source for the region,snowpack plays a key role in regulating the ecological environment,securing agricultural irrigation and promoting socio-economic development.In order to describe the snow change process over a long period of time,we use the snow melt rate as an indicator to build a long time series snow melt model.The research in this article uses the snowmelt rate obtained by the continuous change detection and classification model(CCDC)coupled with SNOW17 in the Google Earth Engine(GEE)to fully understand the snow changes in the Yellow River Basin of the Qinghai-Tibet Plateau from 2000 to 2020.The main results are as follows:(1)The improved CCDC model shows better applicability for both anomaly and trend detection of snow accumulation.The long-term large-scale snowmelt estimation problem is solved by coupling with the snowpack model.The snow melt rate indicators are constructed from the temporal and spatial(elevation)perspectives respectively,construct a time series for each pixel,which can visualize the changes of snow accumulation effectively and provide effective information for simulating and predicting the future state of snow accumulation.(2)The snowmelt rate shows a trend of slow and then fast in the years 2000 to 2020.Analyzing long time series reveals abnormal melting rates in some time periods,causing the snow cycle to change.The snowmelt rate continues to decrease during the anomalous time period,but is greater than zero.Over the years 2000-2020,there is a gradual decrease in the trend of snowmelt rate anomalies and extent.(3)From the spatial distribution of the average snowmelt rate in 2000-2020,the snowmelt rate in the study area during 2000-2014 differed significantly from north to south,and the snowmelt rate in the south was generally larger than that in the north;while in 2014-2020 the difference between north and south was not obvious,showing the characteristics of small regional dispersed changes,and the spatial heterogeneity was strong.In particular,the northern part of the study area,such as Qinghai Lake,shows a significant change in snowmelt rate.(4)As elevation increases,the positive feedback effect of precipitation and temperature on snowmelt rate is gradually increasing.Moreover,the snowmelt rate changes the most in the high altitude above 4600 meters,while the snowmelt rate changes little in the low altitude.