How Well Can We Assess Ozone Production Sensitivity Regimes Using Satellite Remote-sensing?

This presentation highlights results from a NASA Aura Science Team and an Atmospheric Composition Modeling and Analysis Program (ACMAP) project which study the capability to observe trends in ozone (O₃) production regimes using spaceborne sensors. Ultraviolet–visible (UV–Vis) tropospheric column satellite retrievals of formaldehyde (HCHO) (a proxy for volatile organic compound (VOC) reactivity) and nitrogen dioxide (NO₂) (a proxy for nitrogen oxides) are frequently used to investigate the sensitivity of O₃ production to emissions of nitrogen oxides and VOCs. There are challenges that come from using the ratio of HCHO and NO₂ (FNR) to study O₃ production sensitivity such as convolving tropospheric columns to planetary boundary layer (PBL) and surface-level values and errors from chemistry representation, spatial resolution, and retrieval uncertainties. Our studies leveraged a wide variety of measurement data and atmospheric chemistry models to quantify these errors.

We quantified error components of FNR retrievals from Ozone Monitoring Instrument (OMI) and TROPOspheric Monitoring Instrument (TROPOMI) and determined that convolving tropospheric columns to PBL values, chemistry and spatial representation, and satellite retrievals all contribute to total error. However, satellite retrievals, specifically HCHO products, made the largest contribution to the total error in FNRs. To further validate OMI and TROPOMI FNR values, using multiple retrieval algorithms, these remote-sensing products were validated using airborne remote-sensing observations obtained during the Long Island Sound Tropospheric Ozone Study (LISTOS) field campaign. This validation further demonstrated that systematic and random errors from satellite HCHO tropospheric column retrievals contributed to the majority of total FNR errors. Finally, using the information gained from this error analysis, long-term FNR trends are assessed for the Northern Hemisphere using OMI and recent trends for the United States are investigated using OMI, TROPOMI, Ozone Mapping and Profiler Suite (OMPS), and Cross-track Infrared Sounder (CrIS) satellite retrievals.