WRF-Chem data assimilation of NOAA-Unique IASI carbon monoxide retrievals: Impact study on tropospheric ozone increases observed during the 2010 AEROSE Campaign

In this study, we use the combined chemistry and meteorology model WRF-Chem to study the “Ozone Wave-One” maxima over the tropical Atlantic Ocean observed during a NOAA Aerosols and Ocean Science Expedition (AEROSE) campaign in April/May 2010. The NOAA-Unique Infrared Atmospheric Sounding Interferometer (IASI) Spectrometer carbon monoxide trace-gas product showed abundant CO transport from biomass burning emerging from the coast of Sierra Leone and from the developing biomass burning region of equatorial Africa, with carbon monoxide mixing ratios exceeding 130 ppbv in the middle troposphere. Downwind of the biomass burning areas over the tropical Atlantic Ocean, ozonesondes launched during the 2010 AEROSE Campaign detected enhanced ozone at the Equator and at 23°W. Carbon monoxide is a tracer for smoke and precursor for ozone formation. While the WRF-Chem model typically uses global model chemistry as initial conditions, in this study we assimilate the NOAA-Unique IASI retrieved carbon monoxide mixing ratios into the model. The study will advance the understanding of ozone formation processes and accuracy of model ozone mixing ratio estimates compared to observed ozonesonde mixing ratios.