Data Assimilation of CrIS and TROPOMI Satellite CO Concentrations and its Potential for Constraining Global OH

This work investigates the possibility of using high resolution carbon monoxide (CO) observations to constrain global mean hydroxyl radical concentrations ([OH]GM). An improved observational bound on [OH]GM would enhance understanding of chemical reaction rates in the atmosphere, specifically the lifetime of greenhouse gases like methane, and improve global atmospheric model calculations. A multispectral retrieval combining radiances from the Cross-Track Infrared Sounder (CrIS) and TROPOspheric Monitoring Instrument (TROPOMI) satellite instruments has potential to provide high vertical resolution of tropospheric CO. These observations are evaluated against existing measurements from Network for the Detection of Atmospheric Composition Change (NDACC) stations, the Measurement of Pollution in the Troposphere (MOPITT) satellite, and GEOS-Chem chemical transport model calculations. GEOS-Chem adjoint is used to determine sensitivities of each observing platform to estimated GEOS-Chem OH abundance in the troposphere. This should provide insight into OH reaction rates with CO, and whether CO could be used to estimate [OH]GM.