Characterization of Spatial and Temporal Variations of NO2 Concentration in Xinjiang in 2020
Nitrogen dioxide(NO2),as a major atmospheric pollutant,poses a serious threat to human health and the atmo-spheric environment.Investigating the characteristics of the spatial and temporal variations of NO2 concentration and its driving force can provide a better understanding of the natural and anthropogenic factors affecting the variation of NO2 concen-tration.In this paper,the NO2 concentration data were extracted and acquired by the Sentinel-5P satellite from January to December 2020,used the spatial autocorrelation model and Theil-Sen median trend analysis and the Mann-Kendall test to analyze the spatial and temporal distribution pattern of NO2 concentration in Xinjiang and its evolutionary trend,and applied the optimal parameters-based geographical detector(OPGD)to quantify the explanatory power of anthropogenic and natural factors on the changes of NO2 concentration.The explanatory power of anthropogenic and natural factors on the variation of NO2 concentration was quantitatively analyzed by the OPGD model.The results showed that the highest mean value of NO2 concentration in Xinjiang in 2020 was in July and the lowest in February,and the mean value showed an upward trend from the overall perspective.The maximum value of Moran'I for NO2 concentration is 0.921.The minimum value is 0.784,with spatial clustering.The high-high clustering area of NO2 concentration is mainly located in the central part of the study area in the northern foothills of the Tianshan Mountains.In contrast,the low-low clustering area is mainly located in the northern Al-tai Mountain Range and the southern part in the vicinity of the Kunlun Mountain Range.In 2020,about 89.14％of the NO2 concentration in the whole territory is basically unchanged,8.31％of the area has a slight increase in NO2 concentration,2.19％of the area has a significant increase in NO2 concentration,0.36％of the area has a slight decrease,and there is no area with a significant decrease.NO2 concentration is affected by a variety of influencing factors,among which GDP has a greater explan-atory power for NO2 concentration.In contrast,surface temperature has the least explanatory power for it,and GDP interacts significantly with other factors,which shows that anthropogenic activities have a greater influence on the change of NO2 concentration.
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