Spatiotemporal Changes Of Warm Island In Badain Jaran Desert And Its Influencing Factors

Lakes and megadune inter distribute in the hinterland of Badan Jaran Desert,while warm island effect also exist there.Based on the Landsat data,land surface temperature(LST)was calculated to compare the spatiotemporal dynamics of thermal landscape and warm island,then the quantified relationships between influence factors and LST was analyzed through geostatistical method to explore the driving mechanism of LST change and warm island.It is critical in the research of lake cycle and evolution,as it could provide insights for the supply source of lake recharge.The main results are as follows:The mean LST is higher in the southwestern hinterland than northwestern hinterland,which is so called ?warm island effect?.LST is lower in the desert edge,where is covered by strong and relative cold island,while the strong and relative warm island of high LST mainly locate in the desert hinterland,especially in the megadune peak of south lake region.The normal temperature zone with average LST mainly locate in the transition region between desert hinterland and edge.Significant difference exist between strong warm island in megadune peak and strong cold island in megadune bottom.The cold/warm island pattern varied among twelve months and four seasons,while the pattern is more similar between spring and summer,and between autumn and winter.The normal temperature,weak warm island and weak cold island play the dominate role in the seven categories.In the summer,the normal temperature zone and weak cold island are the lowest among four seasons,while the weak warm island is the highest,thus the whole pattern tend to be warmer in summer.The opposite situation happens in winter.Specially,in the desert hinterland,especially in the megadune peak of south lake region,the strong warm island with highest LST has larger distribution than north hinterland without lake group.In 2000-2016,there are not largely change in LST range and cold/warm island,while the warm island distribution difference between south lake region of desert hinterland and north hinterland without lake group.In spring,the center of cold island moved from the north to the south of desert edge,while the warm island center moved from south lake region in desert hinterland to the north.Moreover,the south warm island distribution tended to shrink,and the north warm island range tended to expand.The similar situation happened in autumn.In summer,the pattern of warm island-normal temperature-cold island distributed from west to east,and the warm island in the south lake region became less along time.In 2016,the warm island in north and south desert hinterland became from significant larger distribution in south to nearly the same in north and south.In winter,the strong warm island mainly distributed in the megadune peak of the desert hinterland,especially in the south lake region with large magnitude,and the warm island distributed in north hinterland without lake group tended to increase in 2000-2016.In the influence factors,elevation and slope did not have significant influence on LST,thus terrain has not played an important role in the formation of warm island.Vegetation coverage of NDVI had larger impact on LST,while NDVI increased from the north desert hinterland along the southwest direction.Vegetation coverage was the largest in summer,with larger difference in NDVI between southwest and northeast region,while LST tended to be lower in region with more vegetation.The opposite situation happened in winter,thus vegetation had warming effect in sinter and colder effect in winter.Due to the small area and concentrated distribution of lake,it has limited impact on LST in large scale.In the lake region,the temperature of lake was negatively correlated with its size,as desert has warming effect on lake.Thus the temperature of lake decreased with larger lake size.