Groundbreaking constraints on emissions from GEO-CAPE: case studies of CH4, NH3, SO2 and NO2

While existing remote sensing measurements currently provide valuable sources of top-down constraints on a wide range of emissions of air pollutants and greenhouse gases, geostationary observations hold the potential to significantly advance our scientific understanding of constituent sources in several ways. Over North America, the proposed GEO-CAPE instrument will allow replacement of monthly mean and annual average estimates of emissions, ones that are tuned to current and/or historical observations, with detailed mechanistic models that are capable of projecting outside the envelope of current observations. GEO-CAPE observations are expected to be a major leap forward in observations that can test and constrain such models. In this manner, GEO-CAPE will also allow development of high space and time resolution emission fields that will enable detailed evaluation of other components of a chemical transport model (e.g. boundary layer fluid dynamics). Here we present case studies of the expected benefits of GEO-CAPE observations for constraining bi-directional fluxes of ammonia, the sources and chemical evolution of NOx, the lifetime of SO2, and the emissions of CH4 from anthropogenic vs natural sources. In each case, we illustrate the ways in which geostationary observations provide insight beyond current capabilities with low earth orbit satellites.