Estimating enhancement ratios of nitrogen dioxide, carbon monoxide and carbon dioxide using satellite observations

Abstract. Using co-located space-based measurements of carbon dioxide (CO2) from the Orbiting Carbon Observatory-2 and Observatory-3 (OCO-2/3) monoxide (CO) nitrogen (NO2) TROPOspheric Monitoring Instrument (TROPOMI), we calculate total column enhancements for observations influenced by anthropogenic emissions urban regions relative to clean background values. We apply this method taken over or downwind 27 large (population >1 million) areas around world. Enhancement ratios between species are calculated compared derived four globally gridded inventories. find that these global inventories underestimate CO in many North American European cities our observed enhancement ratios, while smaller differences were found NO2 emissions. further demonstrate calculation intercomparison multiple tracers can help identify underlying biases leading disagreement Additionally, use high-resolution CO2 two (Los Angeles Indianapolis) estimate using good agreement with both a previous modelling study megacity Los California Air Resources Board (CARB) inventory estimates.