Response Of Lake Ice Phenology In Badain Jaran Desert To Climate Change And Hydrological Cycle

Previous studies in the Badain Jaran Desert have focused on hydrological cycle processes and characteristics,vegetation phenology characteristics,land-atmosphere interactions,lake formation and replenishment sources,millennium-scale and chronological scale environmental evolution and climate change,etc.,and the Badain Jaran Desert's response to modern and interannual climate change and hydrological cycle and other basic scientific issues are not sufficiently studied,and most of the meteorological data used are observational data from meteorological stations near the edge of the desert.How to obtain accurate indicators on the interannual time scale,and use these indicators to reflect the response of the Badain Jaran Desert lakes to modern climate changes and hydrological cycles in recent years and during the period of lack of data is worthy of in-depth study.Based on the analysis of multi-source remote sensing images and in-situ field observations,we found that most of the lakes in the hinterland of the Badain Jaran Desert have ice's freeze-up and break-up phenomenon in winter,and many studies have shown that lake ice phenology can be used as one of the proxy indicators of climate change in many regions.Therefore,this thesis focuses on whether lake ice phenology can be used as an indicator or evidence to indicate the response of lakes in the Badain Jaran Desert(extremely arid zone)to modern climate change and hydrological cycle? If so,what are the response mechanisms? By collecting multi-source remote sensing data such as Landast,Sentinel-2,GF-1,GF-6,MODIS,and the in-situ observation data of meteorological,hydrological,and morphological characteristics of lakes in the Badain Jaran Desert and meteorological data of the surrounding areas,this study extracted the lake ice phenology characteristics of typical lakes in the hinterland of the Badain Jaran Desert and surrounding areas for the past 20 years and analyzed their trends and influencing factors,and the main results and conclusions were as follows:(1)The freezing-melting spatial pattern of lakes in the hinterland of the Badain Jaran Desert can be roughly summarized into the following four types: the first type,lake ice spreads from the lake shore to the center of the lake,and the area that freezes earlier melts later;the second type,lake ice spreads from the lake shore to the center of the lake,and the area that freezes earlier melts earlier;the third type,lake ice extends from one shore to the other shore,and the area that freezes earlier melts later;the fourth type,lake ice extends from one shore to the other shore,and the area that freezes earlier melts earlier.(2)The initial form of freezing of lake ice in most of the lakes in the hinterland of the Badain Jaran Desert is to lower the Total dissolved solids(TDS)of the local water bodies after the mixing of springs and groundwater with the lakes,thus making the freezing point of the lake water higher and making the water bodies easier to freeze.The freezing-melting spatial model pattern of lake ice is controlled by multiple factors such as spring and groundwater recharge conditions,TDS,meteorological conditions,lake morphology,etc.The differences between the freezing-melting spatial patterns and temporal characteristics of twin lakes on both sides of the same sand hill or in the same lake basin are a comprehensive reflection of these influencing factors.In addition,the phenomenon of more rapid melting of lake ice on the shore and abnormal increase of lake water temperature in some lakes in February each year indicates a significant increase of groundwater recharge in February,that is,the lake ice phenology is,in a certain sense,a direct reflection of the Badain Jaran Desert lakes receiving regional deep groundwater recharge.(3)The characteristics and trends of lake ice phenology of typical lakes in the hinterland of the Badain Jaran Desert and its surrounding areas from 2000 to 2020 show large differences.The analysis of the factors influencing lake ice phenology proves that the freezing process of lakes in the hinterland of the Badain Jaran Desert and its surrounding areas is more dependent on factors such as lake morphology and local temperature of the lake basin,while the melting process is more likely to be influenced by temperature and TDS.The lake ice phenology of lakes in the hinterland and surrounding areas of the Badain Jaran Desert can accurately reflect the winter half year climate change in the desert and surrounding areas,and its trends are closely related to temperature changes.There is a strong link between the freezing-melting process of Suoguonuoer Lake(Suponaoer)and Buerde Lake and the average temperature in November and March.Therefore,against the background of warming in November and March in the desert periphery,the freeze up duration(FUD)of Suoguonuoer Lake and Buerde Lake is significantly prolonged,the break up duration(BUD)is significantly shortened,and the number of days of frozen duration(FD)is also rapidly reduced.According to the statistical analysis of the lake ice phenology,it is found that in the past 20 years,the hinterland of the Badain Jaran Desert has shown a trend of slowly fluctuating temperature decline in January and February.(4)In terms of duration,the frozen duration(FD)and complete frozen duration(CFD)of the lakes in the hinterland of desert are much smaller than those in the surrounding areas,and the freeze up time starts later and the break up time starts earlier,which is not only the effect of TDS but also the proof of "Warm Island Effect" again.