Geostationary satellite observations of ozone air quality

Ozone in surface air is the primary cause of polluted air in the United States. The current ozone observing network is insufficient either to assess air quality or to fully inform our understanding of the factors controlling tropospheric ozone. This thesis investigates the benefit of an instrument in geostationary orbit for observing near surface ozone using Observing System Simulation Experiments (OSSEs).;An OSSE was performed to define the measurement requirements for geostationary observations of ozone air quality. Hourly observations of ozone from geostationary orbit improve the assimilation considerably relative to daily observation from low earth orbit. There is little propagation of ozone information from the free troposphere to the surface, making instrument sensitivity in the boundary layer is essential. Assimilation of data from a best-case multispectral instrument reduces model error for surface ozone by a factor of two.;A joint assimilation framework was developed to use observations of carbon monoxide as an additional constraint on surface ozone concentrations through exploitation of model error correlations. Ozone-CO error correlations are positive in continental outflow but negative over land on a regional scale. Joint ozone-CO data assimilation provides substantial benefit for informing US ozone air quality if the instrument sensitivity for CO in the boundary layer is greater than that for ozone.;Planned geostationary TEMPO satellite observations of ozone were used in conjunction with complementary surface and low-elevation orbit observations to demonstrate the capability of a future observing system to monitor and attribute air quality exceedances in the Intermountain West. Assimilation of surface measurements alone does not capture elevated ozone levels. Assimilation of TEMPO geostationary observations greatly improves the assimilated model's ability to reproduce ozone exceedances and attribute them to background influence.