气候变化背景下咸阳市大气自净能力变化特征

Characteristics of atmospheric self-purification capacity in Xianyang city under the background of climate change

利用咸阳市12个国家气象站1962—2021年地面气象观测资料和咸阳市2015—2021年环境空气质量监测资料,计算1962—2021年逐日大气自净能力,利用M-K和滑动t检验法开展突变检验,同时分析大气空间变化特征。结果表明:咸阳市大气自净能力不仅呈现出明显的年、月、季特征,且年代际变化总体呈减弱趋势,大气自净能力的气候倾向率为-1.22×10^(4)km^(2)·a^(-1)·(10 a)^(-1)。1962—2021年总体为增强→减弱→增强的过程,最低年(2002年)与最高年(1969年)相比偏低70%。各季有明显差异,大气自净能力大小依次为春季>夏季>秋季>冬季。年平均风速与年平均自净能力的相关系数为0.98,小风日数与大气自净能力相关系数为-0.91,非小风日是小风日自净能力的6.2倍。降水日数及日、月降水量与大气自净能力的相关系数分别为0.23、0.02和0.07,中雨量级降水大气自净能力最强。年与四季平均大气自净能力的空间分布大致呈东高西低、北高南低特征,其中武功、兴平、秦渭区处于较小的大气自净能力区域。AQI和PM_(2.5)浓度与大气自净能力呈反相关关系。两种突变检验方法综合确定大气自净能力的突变年发生在2010年,春夏季突变年发生在2011年,秋冬季突变年发生在2010年。

By utilizing the ground meteorological observation data from 12 national meteorological stations in Xianyang city from 1962 to 2021,alongside the ambient air quality monitoring data from 2015 to 2021,the daily atmospheric 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 decreasing trend observed in decadal variation.The climate tendency rate of the air self-purification capacity is-1.22×10^(4)km^(2)·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 highest 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 atmospheric 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,respectively.In terms of spatial distribution,the annual and seasonal average atmospheric self-purification capacity is generally 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 PM_(2.5)concentration are inversely correlated with atmospheric self-purification capacity.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.