OMI和TROPOMI的中国对流层NO_(2)污染数据的时空对比分析

Spatial and temporal comparison of tropospheric NO_(2)pollution data from OMI and TROPOMI in China

基于2018年12月—2019年11月臭氧层观测仪(Ozone Monitoring Instrument,OMI)和对流层观测仪(TROPOspheric Monitoring Instrument,TROPOMI)遥感反演产品数据,统计两种数据在中国区域对流层NO_(2)柱浓度数据缺失率,分析得出两者的时空分布差异。结果表明:(1)该时间段内,两种传感器数据缺失率呈现“S”形的变化趋势,TROPOMI月数据缺失率低于OMI,TROPOMI年平均数据缺失率为3.98%,OMI年平均数据缺失率为36.22%,造成该结果的原因可能是不同仪器的分辨率不同。(2)在中国区域内,两种数据存在一定的相关性,相关系数为0.844,但TROPOMI获得的对流层NO_(2)年平均柱浓度值大于OMI;从季节差异上来看,TROPOMI获得的结果同样相对OMI的结果高出57.5%,造成OMI结果偏低的原因可能是OMI传感器在有云(非晴空)情况下用其他卫星观测进行校正,使得结果平均降低15%,但不会影响季节变化趋势。(3)季节相关性方面,秋、冬两季相关性较好,春、夏两季相对较差,是由于春、夏季节NO_(2)柱浓度易受其他气体污染物的影响,且两种传感器在反演方法上有所不同,会造成一定的系统误差。(4)在重污染情况下,TROPOMI传感器获得的地域范围相比于OMI大1.54%,只有在冬季污染最为严重的情况下,TROPOMI获得的污染区域相比于OMI小0.86%。(5)在时空差异上,东部地区两者差异明显,TROPOMI获得的月平均结果相比于OMI的结果大10.21%,西部差异不大,中国不同城市群之间的结果也存在差异。

Based on the remote sensing retrieval products of the Ozone Monitoring Instrument(OMI)and the TROPOspheric Monitoring Instrument(TROPOMI)from December 2018 to November 2019,the data miss rate of the tropospheric NO_(2)column concentration from the two sensors in China is calculated,and the difference in spatial and temporal distribution of the two sensors’data is also analyzed.The results are shown below.(1)During this period,the data miss rates from both sensors present a“S”shape change;the monthly data miss rate from TROPOMI is lower than that from OMI;the annual mean data miss rates from TROPOMI and OMI is 3.98%and 36.22%,respectively.The different resolutions of different sensors may account for the result.(2)In China,there is a certain correlation between the tropospheric NO_(2)concentration data from the two sensors,and the correlation coefficient is 0.844.The annual mean tropospheric NO_(2)column concentration from TROPOMI is higher than that from OMI.As for seasonal difference,the result of TROPOMI is 57.5%higher than that of OMI,because the OMI data is modified using other satellite observations in the presence of clouds,which reduces the result by 15%on average but does not affect seasonal variation trend.(3)Furthermore,the correlation is found satisfactory in autumn and winter,but relatively poor in spring and summer.This is because the NO_(2)column concentration in spring and summer is easily affected by other gaseous pollutants,and the retrieval methods of the two sensors are different,which causes some systematic errors.(4)In the case of heavy pollution,the pollution area detected by TROPOMI is 1.54%larger than that by OMI for most seasons,and the pollution area obtained by TROPOMI is 0.86%smaller than that by OMI only in the case of the most serious pollution in winter.(5)The spatial and temporal differences between TROPOMI and OMI data are obvious in eastern China,and the monthly mean result of TROPOMI is 10.21%larger than that of OMI,while the differences in western China are not significant.In addition,the results of different urban agglomerations in China are also different.