Abstract Quantifying the carbon dioxide (CO 2 ) to nitrogen oxides (NO x ) emission ratio (CNER) from space provides valuable information on combustion efficiency and pollution control. We develop a satellite‐based inversion framework that derives CNER from co‐located CO 2 and NO 2 enhancements observed by OCO‐2 and TROPOMI, combining cross‐sectional flux fitting with an exponentially modified Gaussian correction for NO 2 decay. Applied to six overpasses of three isolated U.S. coal‐fired power plants, the retrieved CNER (938–4166) agrees with hourly in situ measurements ( r = 0.67) within a factor of two. CNER exhibits greater temporal stability (±30%) than individual fluxes of each species (±60%) and shows pronounced differences among plants, reflecting fundamental differences in fuel composition and the tiered impact of pollution control technologies, as validated by a unit‐level statistical analysis. Our findings suggest that CNER could serve as a robust, satellite‐retrievable metric for combustion characterization while highlighting its potential for upcoming joint CO 2 –NO 2 monitoring missions.
Wang et al. (Tue,) studied this question.