Improvement of the satellite-derived NO x emissions on air quality modeling and its effect on ozone and secondary inorganic aerosol formation in the Yangtze River Delta, China

Yang, Yang; Zhao, Yu; Zhang, Lei; Zhang, Jie; Huang, Xin; Zhao, Xuefen; Zhang, Yan; Xi, Mengxiao; Lu, Yi

We developed a top-down methodology combining the inversed chemistry transport modeling and satellite-derived tropospheric vertical column of NOinline-formula2 and estimated the NOinline-formulax emissions of the Yangtze River Delta (YRD) region at a horizontal resolution of 9 km for January, April, July, and October 2016. The effect of the top-down emission estimation on air quality modeling and the response of ambient ozone (Oinline-formula3) and inorganic aerosols (SOinline-formula M6inlinescrollmathml normal 4 normal 2 - 13pt17ptsvg-formulamathimg4a53e7d1f00f4334c934356877052515 acp-21-1191-2021-ie00001.svg13pt17ptacp-21-1191-2021-ie00001.png , NOinline-formula M7inlinescrollmathml normal 3 - 9pt16ptsvg-formulamathimg76bbd0535ad9c3e987722e2e722d5d00 acp-21-1191-2021-ie00002.svg9pt16ptacp-21-1191-2021-ie00002.png , and NHinline-formula M8inlinescrollmathml normal 4 + 8pt15ptsvg-formulamathimga9b2fdba183dceff94210c316afa95ef acp-21-1191-2021-ie00003.svg8pt15ptacp-21-1191-2021-ie00003.png , SNA) to the changed precursor emissions were evaluated with the Community Multi-scale Air Quality (CMAQ) system. The top-down estimates of NOinline-formulax emissions were smaller than those (i.e., the bottom-up estimates) in a national emission inventory, Multi-resolution Emission Inventory for China (MEIC), for all the 4 months, and the monthly mean was calculated to be 260.0 Gg/month, 24 % less than the bottom-up one. The NOinline-formula2 concentrations simulated with the bottom-up estimate of NOinline-formulax emissions were clearly higher than the ground observations, indicating the possible overestimation in the current emission inventory, attributed to its insufficient consideration of recent emission control in the region. The model performance based on top-down estimate was much better, and the biggest change was found for July, with the normalized mean bias (NMB) and normalized mean error (NME) reduced from 111 % to inline-formula−0.4 % and from 111 % to 33 %, respectively. The results demonstrate the improvement of NOinline-formulax emission estimation with the nonlinear inversed modeling and satellite observation constraint. With the smaller NOinline-formulax emissions in the top-down estimate than the bottom-up one, the elevated concentrations of ambient Oinline-formula3 were simulated for most of the YRD, and they were closer to observations except for July, implying the VOC (volatile organic compound)-limited regime of Oinline-formula3 formation. With available ground observations of SNA in the YRD, moreover, better model performance of NOinline-formula M17inlinescrollmathml normal 3 - 9pt16ptsvg-formulamathimg5a2143864edd3f7cf8f1639018917994 acp-21-1191-2021-ie00004.svg9pt16ptacp-21-1191-2021-ie00004.png and NHinline-formula M18inlinescrollmathml normal 4 + 8pt15ptsvg-formulamathimgc6cfd3dc5fa316f8765c9850f4d65a8f acp-21-1191-2021-ie00005.svg8pt15ptacp-21-1191-2021-ie00005.png was achieved for most seasons, implying the effectiveness of precursor emission estimation on the simulation of secondary inorganic aerosols. Through the sensitivity analysis of Oinline-formula3 formation for April 2016, the decreased Oinline-formula3 concentrations were found for most of the YRD region when only VOC emissions were reduced or the reduced rate of VOC emissions was 2 times of that of NOinline-formulax, implying the crucial role of VOC control in Oinline-formula3 pollution abatement. The SNA level for January 2016 was simulated to decline 12 % when 30 % of NHinline-formula3 emissions were reduced, while the change was much smaller with the same reduced rate for SOinline-formula2 or NOinline-formulax. The result suggests that reducing NHinline-formula3 emissions was the most effective way to alleviate SNA pollution of the YRD in winter.



Yang, Yang / Zhao, Yu / Zhang, Lei / et al: Improvement of the satellite-derived NOx emissions on air quality modeling and its effect on ozone and secondary inorganic aerosol formation in the Yangtze River Delta, China. 2021. Copernicus Publications.


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