Observing System Simulation Experiments (OSSE) for Future Geostationary Satellite to Constrain Aerosol Emissions through GEOS-Chem Adjoint

Aerosols in the troposphere have great impacts on weather, climate, and human health. However, aerosol predictions by current chemistry transport models remain inaccurate, in no small part resulting from uncertainty of aerosol emission estimates. Here, we conducted observing system simulation experiments (OSSE) for future geostationary satellite to assess the potential of using hourly aerosol optical depth (AOD) retrievals to constrain emissions. Specifically, hourly pseudo AOD observations over North America were generated by WRF-Chem, and were applied to constrain emissions through GEOS-Chem adjoint model in two experiments. One experiment simulated assimilating polar-orbiting observations saying MODIS by providing data once a day, while another experiment simulated assimilating geostationary satellite observations saying TEMPO by providing data hourly in the daytime. Results show that SO2, NOx, and NH3 emissions constrained by high temporal resolution observations get better agreement with WRF-Chem emissions in terms of total amount and spatial distribution. This suggests that TEMPO could offer better constraints for aerosol emissions than polar-orbiting satellites.