A trend analysis based on observations from GOME,SCIAMACHY,and OMI of the tropospheric NO2 column from 1996 to 2016 in North China Plain is presented.The columnar NO2 showed a rapid increase from 1996 to 2011,especially in Beijing,Tianjin,and Hebei.On the contrary,a significant decrease in tropospheric NO2 column was observed in North China Plain from 2012 to 2016 because of the effective control strategies from the twelfth Five-Year Plan.This study aims to investigate the spatial variations in tropospheric NO2 trend from 1996 to 2016 in North China Plain,from which the driving factors of economic development and polices were derived.First,the liner regression analysis method was used among tropospheric NO2 columns from GOME,SCIAMCHY,and OMI.Second,the spatial variations in NO2 trend in North China Plain were investigated using multivariate linear regression.Results showed that NO2 columns in North China Plain increased by 10.3％ per year from 1996 to 2011,and then decreased by 8.77％ per year from 2012 to 2016 because of the rapid economic development,environmental protection policy,and rainfall.From 1996 to 2011,high NO2 columns were mainly concentrated in Beijing,Tianjin,Tangshan,Baoding,Dezhou,Jinan,Nanjing,Changzhou,and Wuxi,with the value of NO2 columns being larger than 600× 1013 molec·/cm2.Low NO2 columns were mainly concentrated in northern Hebei and southwestern Henan provinces,with the value of NO2 columns being less than 200× 1013 molec·/cm2.The trend of NO2 columns had an acceptable agreement (0.54) with NO2 concentration in the space,indicating that the increase was mostly distributed in the region with high value.From 2012 to 2016,the high value of NO2 columns spread to southern Hebei,northern Henan,and western Shandong.Generally,the average NO2 column from 2012 to 2016 was considerably higher than that from 1996 to 2011.The trend of NO2 column decreased from 2012 to 2016 over North China Plain probably because of the effective control strategies implemented during the twelfth Five-Year Plan.In addition,tropospheric NO2 column showed a significant reduction during typical events in North China Plain,such as,Beijing Olympics,military parade,and Nanjing Youth Olympic Games.The tropospheric NO2 columns measured by GOME,SCIAMACHY,and OMI could be used to indicate the variations of NOx emissions.Results showed that the increase and decrease trends may be affected by rapid economic development,environmental protection policies,and rainfall.%为探讨1996年以来华北平原对流层NO2柱浓度变化的空间特征,基于GOME、SCIAMACHY和OMI卫星传感器的监测数据,以SCIAMACHY的NO2柱浓度为基准,根据建立的GOME和SCIAMACHY,SCIAMACHY和OMI之间的相关关系,校正GOME和OMI监测的NO2数据;利用线性正弦曲线模型拟合方法研究1996年-2016年长时间序列华北平原对流层NO2变化的空间分布特征.结果显示,华北平原对流层NO2浓度自1996年开始持续上升,到2011年达到最高值,然后呈现下降趋势.该变化趋势主要受经济发展和环保政策的双重影响.1996年-2011年,NO2柱浓度高值区分布在北京市、天津市、河北唐山市和保定市、山东德州市和济南市、安徽滁州市以及江苏南京市、常州市和无锡市,并且具有较高增长率;2012年-2016年NO2柱浓度平均值远高于1996年-2011年NO2柱浓度平均值,高值地区范围扩大,分布在河北南部、河南北部和山东西部,但华北平原地区NO2柱浓度均呈现负增长,表明“十二五”规划提出的大气环保政策取得了显著成效.同时,对流层NO2柱浓度可以反映典型环保事件如北京奥运会、国庆阅兵和南京青奥会时期大气环保政策的实施效果.
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