Characteristics of atmospheric self-purification capacity in Xianyang city under the background of climate change
By utilizing the ground meteorological observation data from 12 national meteorological stations in Xian-yang city from 1962 to 2021,alongside the ambient air quality monitoring data from 2015 to 2021,the daily atmos-pheric self-purification capacity from 1962 to 2021 was calculated.The mutation tests were employed using Mann-Kendall(M-K)and sliding t-test(MT)methods,and the spatial characteristics were studied.The results show that the air self-purification capacity in Xianyang city exhibits distinct annual,monthly,and seasonal patterns,with a de-creasing trend observed in decadal variation.The climate tendency rate of the air self-purification capacity is-1.22×104 km2·a-·1(10 a)-1.From 1962 to 2021,the overall trend has shown an initial increase,followed by a decrease,and then another increase,with the lowest year(2002)recording a 70%decrease compared to the high-est year(1969).The sequence of atmospheric self-purification capacity from high to low is summer,spring,fall,winter.The correlation coefficient between the annual average wind speed and the annual average atmospheric self-purification capacity is 0.98.The correlation coefficient between the number of light wind days and the atmospher-ic self-purification capacity of the atmosphere is-0.91,with the self-purification capacity of non-light wind days being 6.2 times that of light wind days.The correlation coefficients between the number of precipitation days,daily precipitation,monthly precipitation,and atmospheric self-purification capacity were 0.23,0.02,and 0.07,respec-tively.In terms of spatial distribution,the annual and seasonal average atmospheric self-purification capacity is gen-erally higher in the east and lower in the west,as well as higher in the north and lower in the south.Regions such as Wugong,Xingping,Qindu,and Weicheng exhibit lower atmospheric self-purification capacity.Additionally,the Air Quality Index(AQI)and PM2.5 concentration are inversely correlated with atmospheric self-purification capac-ity.The abrupt change year of annual atmospheric self-purification capacity was identified through two abrupt change tests in 2010,with spring and summer experiencing an abrupt change in 2011,and autumn and winter in 2010.
Atmospheric self-purification capacityMeteorological elementsAmbient air qualityMutations tes-ting
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