Temporal And Spatial Variation Of Surface Temperature And Influencing Factors Analysis In Xinjiang From 2001 To 2019

The surface temperature is a physical quantity that characterizes the temperature of the ground-air interface,and is also the main parameter for evaluating climate change.Analyzing the temporal and spatial changes of ground temperature and interacting with influencing factors such as land use and land surface parameters has important scientific significance for in-depth understanding of the interaction between the ground surface and the atmosphere,clarifying the mechanism of climate change strain,and detecting future trends of ground temperature changes.Xinjiang is located in northwestern China,deep inland,with a dry climate,a vast area,and complex topography.There are obvious differences in climatic characteristics across Xinjiang,and the evolution of surface temperature is diverse.This study is supported by RS and GIS technology to discuss the temporal and spatial changes of surface temperature and various influencing factors in Xinjiang in the past 19 years.Based on data products such as MODIS surface temperature(MOD11A2),surface albedo(MCD43A3),and enhanced vegetation index(MOD13A1),the climatic tendency rate method,trend analysis method,correlation analysis and other methods are used to explore the surface temperature of Xinjiang in2001-2019 The law of annual temporal and spatial evolution and its response to influencing factors,According to the research results,the following conclusions can be drawn:(1)On the time scale of Xinjiang's surface temperature: The interannual variation of Xinjiang's surface temperature in the past 19 years showed a warming trend,with an average annual climate tendency rate of 0.015°C/a,from 20.141°C in2001 to 20.198°C,with a temperature increase of 0.057°C;The inter-annual variation of the monthly average surface temperature showed an upward trend in January,March,Apirl,July,and December;The annual change of the surface temperature is in a single-peak change trend of first increasing and then decreasing.The highest value appeared in July,reaching 38.66?,and the lowest ground temperature reached-4.46? in January.(2)On the spatial scale of Xinjiang's surface temperature: Xinjiang's annual average surface temperature gradually increases from north to south.The surface temperature in the southeast region is higher than that in the northwest region.The highest annual average surface temperature in the entire region appears in the Kashgar and Hotan regions of southern Xinjiang;The surface temperature is relatively stable and low temperature regions in the northern Altai Mountains and southern Kunlun in each month,and the relatively stable high temperature regions are the Tarim Basin and surrounding urban areas;The change trend of LST from 2001 to 2019 ranges from 0.834 to-1.012°C.The warming trend is mainly in northern Xinjiang and the eastern region,and the cooling trend mainly appears on both sides of the Tianshan Mountains and Aksu area.The basically unchanged trend is unevenly distributed throughout the entire The study area is spread and distributed,mainly in the Tarim Basin.(3)The enhanced vegetation index in Xinjiang showed an increasing trend from 2001 to 2019,from 0.055 in 2001 to 0.065 in 2019,with the highest and lowest values in 2001 and 2013 respectively;The changes within the EVI show a "single-peak" pattern,gradually increasing to a peak and then gradually decreasing,with the highest value appearing in June,July,and August;EVI as a whole presents a spatial distribution characteristic of "high in the western half and low in the eastern half".In the past 19 years,the change trend of EVI has ranged from-0.01 to 0.02,showing an increasing trend range of 5.42% of the entire region,mainly distributed in southern Xinjiang In the plain oasis area and the northern slope area of Tianshan Mountain,70.95% of the area showed a decreasing trend,concentrated in the Ili River Valley and Bayinbuluke Grassland.(4)The surface albedo in Xinjiang from 2001 to 2019 showed a slight downward trend,with fluctuations ranging from 0.244 to 0.269,with the highest and lowest values appearing in 2006 and 2015,respectively;The change of surface albedo during the year showed a trend of first decreasing and then increasing,showing a "U"-shaped change pattern as a whole,with the highest surface albedo in December,January and February;The surface albedo in Xinjiang as a whole shows a spatial distribution pattern of "high in the northwest and low in the southeast".The area around the Altai Mountains and the Yili River Valley has a relatively high surface albedo.The change trend of the surface albedo in the past 19 years is between-0.01?0.02.The area showing an increasing trend accounted for 20.32% of the entire region,mainly in northern Xinjiang.The area showing a decreasing trend accounted for 21.42% of the total area,and the basically unchanged area accounted for 58.26%.The distribution was uneven and mainly appeared in desert areas.(5)Influencing factors of surface temperature: The interannual changes of average LST in all land use types in Xinjiang in the past 19 years showed a warming trend.Among the land types,the most active LST changes are canopy shrubs,deciduous broad-leaved forests,etc.The years are 2008 and 2013,in which bare soil and residential areas contribute significantly to LST warming,while vegetation coverage and waters contribute to LST cooling;The surface temperature in Xinjiang decreases with the increase in altitude,and the annual average LST decreases by0.53? per 500 m altitude;The changes of enhanced vegetation index and surface temperature have different correlation rules in various regions of Xinjiang.The strongest negative correlation is distributed in the southwestern Tianshan Mountains and the Yili River Valley.The positive correlation is mainly distributed in the Kunlun Mountains and the upper part of the Junggar Basin.Temperature and EVI changes have a strong sense and correlation in time;The correlation coefficient between the surface albedo and the surface temperature change is less than 0 in most areas of Xinjiang,and there is a negative correlation.The strongest negative correlation is located in the Altai Mountains and the northwest and southeast margins,and the higher positive correlation is in the Tarim Basin.And the central area,the increase in surface albedo is an important factor causing the decrease in surface temperature.