Articles | Volume 16, issue 8
https://doi.org/10.5194/acp-16-5283-2016
https://doi.org/10.5194/acp-16-5283-2016
Research article
 | 
28 Apr 2016
Research article |  | 28 Apr 2016

NOx lifetimes and emissions of cities and power plants in polluted background estimated by satellite observations

Fei Liu, Steffen Beirle, Qiang Zhang, Steffen Dörner, Kebin He, and Thomas Wagner

Abstract. We present a new method to quantify NOx emissions and corresponding atmospheric lifetimes from OMI NO2 observations together with ECMWF wind fields without further model input for sources located in a polluted background. NO2 patterns under calm wind conditions are used as proxy for the spatial patterns of NOx emissions, and the effective atmospheric NOx lifetime is determined from the change of spatial patterns measured at larger wind speeds. Emissions are subsequently derived from the NO2 mass above the background, integrated around the source of interest.

Lifetimes and emissions are estimated for 17 power plants and 53 cities located in non-mountainous regions across China and the USA. The derived lifetimes for the ozone season (May–September) are 3.8 ± 1.0 h (mean ± standard deviation) with a range of 1.8 to 7.5 h. The derived NOx emissions show generally good agreement with bottom-up inventories for power plants and cities. Regional inventory shows better agreement with top-down estimates for Chinese cities compared to global inventory, most likely due to different downscaling approaches adopted in the two inventories.

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Short summary
We present a new method to quantify NOx emissions and corresponding atmospheric lifetimes from OMI NO2 observations together with ECMWF wind fields without further model input for sources located in polluted background. The derived NOx emissions show generally good agreement with bottom-up inventories for power plants and cities. Global inventory significantly underestimated NOx emissions in Chinese cities, most likely due to uncertainties associated with downscaling approaches.
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