8A.4 Inverse Modelling of Natural NOx Emissions and Implications for Ozone in the United States

Wednesday, 15 January 2020: 9:15 AM
206B (Boston Convention and Exhibition Center)
Qiyang Yan, Georgia Institute of Technology, Atlanta, GA; and Y. Wang, J. Li, and C. Smeltzer

Natural sources of nitrogen oxides (NOx=NO+NO2), including lightning and soil NOx, are estimated to contribute more than 30 percent of total NOx emissions in the United States. Lightning is the major source of NOx emissions in the middle and upper troposphere. Due to the difficulties in understanding underlying processes and quantifying variant temporal and spatial distributions of natural NOx, estimations of natural NOx emissions remain significantly uncertain compared to anthropogenic sources. Satellite measurements of total NO2 columns provide important top-down information to NOx emission estimations. Previous estimations of natural NOx relied mainly on ground-based measurements and satellite observations in natural NOx dominant regions, the observations of which are limited. In this study, we inversely derive the natural NOx emissions on a daily basis from a source-separated model, which could compute source-specific NO2 columns for each natural and anthropogenic sources, using the 3-D Regional chEmical trAnsport Model (REAM) and the Ozone Monitoring Instrument (OMI) measurements during summer 2011. Results suggest a reduction in natural NOx emissions of the model. We also analyze how ozone responses to projected natural NOx emission reductions in the United States.
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