Inverse Modelling of Source-Specific Nitrogen Oxide Emissions Using Satellite Observations in the United States

Satellite observations of nitrogen dioxide (NO₂) provide valuable information in estimating nitrogen oxide (NO_x) emissions. Improved understanding of NO_x emissions from anthropogenic and natural sources is essential for the development of efficient emission control strategies. In this study, we improve upon the inversion method of total anthropogenic emissions using satellite observations and estimate source-specific emissions of NO_x from various anthropogenic sources, lightning and soils in 2011 over the United States. Emissions from eight sectors are estimated incuding soil, industry, Electric Generating Units (EGU), onroad, nonroad, oil and gas, aircraft, and lightning. We derive posteriori source-specific NO_x emissions from these sources using NO₂ column measurements from the Ozone Monitoring Instrument (OMI) and the 3-D Regional chEmical trAnsport Model (REAM). Inversion results suggest a reduction of mobile emissions and increases in non-road, industry, and oil and gas sources.