新疆典型沙漠和绿洲植被-水汽-地表温度相关性分析

Vegetation-water vapor-land surface temperature correlation analysis of typical deserts and oases in Xinjiang

为探讨新疆不同区域沙漠、绿洲地表温度(Land surface temperature,LST)、归一化植被指数(Normalized difference vegetation index,NDVI)及大气水汽含量三者间的相关关系,利用2001-2019年MOD13C3植被指数、MOD11C3地表温度以及2013-2017年Suomi NPP VIIRS水蒸气含量数据,运用Slope趋势分析方法对该问题进行研究。结果表明:(1)2001-2019年新疆植被指数年平均值整体呈增加趋势,绿洲增加尤为明显。地表温度年平均值变化为绿洲白天减少、夜晚增加,年温度差值减少;沙漠白天夜晚均增加,年温度差值增加。(2)全疆的NDVI、大气水汽含量及地表温度三者的月值数据彼此呈正相关关系。植被增加可减少地表温差和大气水汽差,在北疆绿洲的高植被覆盖区表现明显。绿洲对于生态环境的调控作用优于沙漠,北疆绿洲调控作用优于南疆。(3)塔克拉玛干沙漠在每年3-10月夜晚地表逆温和逆湿现象明显,导致夜晚大气水汽含量高于白天。南疆绿洲受沙漠环境及植被增加的双重影响,近年来夜晚水汽含量高于白天水汽含量的月份逐渐减少,主要集中在夏季。研究结果有利于从宏观层面认识新疆气候变化,为新疆生态环境保护提供有价值的参考。

To explore the correlation among the land surface temperature(LST),normalized difference vegetation index(NDVI),and atmospheric water vapor content in different regions of Xinjiang,China,the MOD13C3 NDVI and LST from 2001 to 2019 and Suomi NPP VIIRS water vapor content from 2013 to 2017 were used to study this problem using the slope trend analysis method.The results are as follows.(1)From 2001 to 2019,the annual average value of NDVI showed an overall increasing trend,especially in the oasis.The annual average change of LST is that the oasis decreases during the day and increases at night,and the annual temperature difference decreases.The desert LST increases during the day and night,and the annual temperature difference increases.(2)The monthly data of NDVI,atmospheric water vapor content,and LST are positively correlated.The increase in vegetation can reduce the surface temperature and atmospheric water vapor differences,which is obvious in the high vegetation coverage area of the oasis in northern Xinjiang.Oasis is better than the desert in regulating the ecological environment,and an oasis in northern Xinjiang is better than that in southern Xinjiang.(3)In the Taklimakan Desert,the surface temperature and humidity inversion are obvious at night from March to October every year,which lead to higher atmospheric water vapor content at night than during the day.Oasis of southern Xinjiang affected by desert environment and vegetation increase.The months when the water vapor content at night is higher than that during the day gradually decrease in recent years,mainly concentrated in summer.The research results are useful in understanding climate change from a macrolevel and providing a valuable reference for ecological environment protection in Xinjiang.