Study on phenological changes of lake ice in Mongolian Plateau from 2000 to 2021
Lake ice phenology is the seasonal change of lake freezing,melting and other phenomena,which plays an important role in indicating regional climate change.This article is based on Google Earth Engine(GEE),using 250 m spatial resolution MODIS surface reflectance products MOD09GQ and MYD09GQ,and Landsat series remote sensing data to analyze the lake conditions of 10 large lakes(area greater than 200 km2)on the Mongolian Plateau from 2000 to 2021.Ice phenology changes were studied,and their correlation with chang-es in temperature,precipitation,and Mongolian high pressure was analyzed using meteorological data.The re-sults show that:(1)All lakes begin to freeze from November to mid-to-early December,and are completely fro-zen from mid-November to late December,entering the lake freeze period;they begin to melt in late April of the following year,and all lakes are completely frozen by the end of May.After thawing,the average lake freeze period for the 10 lakes is 151 days.(2)The overall phenology of lake ice in the study area shows the trend of de-layed freezing date,advanced melting date,complete lake freezing period,and shortened lake ice existence peri-od.The specific performance is that the average change rate between the day of initial freezing and the day of complete freezing is 1.88 d·(10a)-1 and 1.91 d·(10a)-1,respectively;the average rate of change on the day of initial thawing and complete thawing is-3.45 d·(10a)-1 and-3.41 d·(10a)-1;the average change rates of the lake ice existence period and complete freezing period are-5.32 d·(10a)-1 and-5.37 d·(10a)-1,respectively.(3)Climate change will affect the phenological changes of lake ice in the study area,and temperature is the key factor affecting the phenological changes of lake ice.Rising temperatures lead to a delay in the freeze-up start date(FUS)of lake ice,an advance in the break-up start date(BUS),and a shortening of the complete freezing duration(CFD).At the same time,the phenological properties of lake ice in some lakes will be affected by the Mongolian high pressure in winter,which will bring the cold air will cause the lake ice break-up duration(BUD),lake ice cover duration(ICD),and complete freezing duration(CFD)to increase.
lake ice phenologyMODISLandsatthreshold methodNDSIclimate change
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