Spatio-temporal Characteristics And Influencing Factors Of Enhanced Vegetation Index (EVI) And Aerosol Optical Depth (AOD) In Tarim Basin From 2001 To 2020

Under the background of global environmental change,the response of surface vegetation to climate change and human activities has attracted widespread attention.The ecological environment in the extremely arid area of Tarim Basin is very fragile and sensitive to global environmental changes.Based on remote sensing and meteorological data,this paper analyzes the temporal and spatial variation characteristics of Enhanced Vegetation Index(EVI)in Tarim Basin from 2001 to 2020,identifies the proportion and spatial distribution pattern of vegetation index increase,decrease and relative stability in Tarim Basin in recent 20 years,analyzes the effects of climatic factors such as temperature,precipitation and human activities such as afforestation on EVI.investigate the response of Aerosol Optical Depth(AOD)to EVI and climatic factors.The main results are as follows:(1)From the perspective of time series,due to the scarcity of precipitation,the 20-year mean EVI in Tarim Basin is low(0.0594).The EVI in Tarim Basin has fluctuatlly increased in the past 20 years,showing a trend of vegetation improvement.From the perspective of spatial distribution,the high value area of EVI is mainly distributed in the oasis zone in the middle and upper reaches of the Tarim River,Yeerqiang River,Hotan River,Keriya River,Chechen River and other rivers at the edge of the basin.From the perspective of spatial change,the oasis area in the middle and upper reaches of the peripheral river systems of the Tarim Basin from 2001 to 2020 showed an expanding trend(19.30%);the significant reduction of EVI occurred sporadically in the lower reaches of the Tarim River in the eastern part of the basin(0.72%);and the EVI in other areas remained relatively stable(79.98%).(2)The annual mean temperature is 13.67 ℃ and the annual precipitation is44.28 mm in Tarim Basin from 2001 to 2020.From the perspective of time series,the change of annual mean temperature was not significant,but the annual precipitation showed an increasing trend,with the change rate 0.51 mm / year.The annual mean EVI was positively correlated with annual precipitation and cumulative afforestation area,but not with annual mean temperature.From the perspective of spatial distribution,the change rate of EVI is positively correlated with the change rate of annual precipitation and annual mean temperature.The increase of EVI at the edge of the basin,especially in the northwest of the basin,is related to the increase of annual precipitation and the local increase of annual mean temperature in this region.(3)The change of AOD is not significant in Tarim Basin from 2001 to 2020.From the perspective of spatial distribution,the decrease of annual mean wind speed,the increase of annual precipitation and the increase of annual EVI value in Tarim basin significantly promote the decrease of AOD.