Evaluation of Surface Ozone Chemistry in Regulatory Air Quality Models through the Use of OMI Observations and Ground-Based Data

Determining the chemical conditions that lead to the formation of surface ozone, a pollutant regulated by the federal government, is of great interest to scientists and policy makers. The lack of detailed observations of ozone precursors, such as NO_x and volatile organic compounds (VOCs), limits our ability to precisely identify the non-linear chemistry that determines ozone production over large regions of the United States. Earlier studies have used the ratio of satellite observations of column HCHO, a VOC proxy, to column NO₂ to estimate ozone sensitivity. Recent work has highlighted the regional and temporal variations of this ratio that must be accounted for. This analysis focuses on the ratio of column HCHO/NO2 as observed from space and representation of this quantity in regulatory air quality models using a number of assumptions regarding the model framework. The use of this ratio as a proxy for the sensitivity of surface ozone to photochemical regime and as a prognosticator of future changes in surface ozone, is investigated.