Spectroinetric observations (1100 A to 1800 A) of the ultraviolet radiance of Earth's atmosphere have been obtained by the Horizon Ultraviolet Program (HUP) sensor froni Space Shuttle altitude at two different points in the solar cycle. Most of the radiance measurements were made during horizon scans of the earthlimb or while the HUP field of view was directed toward nadir. The expected variation of dayglow radiance with solar zenith angle (SZA) in the several spectral bands was observed. These results compare favorably to the predictions of a preliminary version of the Atmospheric Ultraviolet Radiance Integrated Code (AURIC).

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We use a regional scale photochemical transport model to investigate the surface concentrations and column integrated amounts of ozone (O3) and nitrogen dioxide (NO2) during a pollution event that occurred in the St. Louis metropolitan region in 2012. These trace gases will be two of the primary constituents that will be measured by TEMPO, an instrument on a geostationary platform, which will result in a dataset that has hourly temporal resolution during the daytime and ~4 km spatial resolution. Although air quality managers are most concerned with surface concentrations, satellite measurements provide a quantity that reflects a column amount, which may or may not be directly relatable to what is measured at the surface. The model results provide good agreement with observed surface O3 concentrations, which is the only trace gas dataset that can be used for verification. The model shows that a plume of O3 extends downwind from St. Louis and contains an integrated amount of ozone of ~ 16 DU (1 DU = 2.69 x 10 16 mol. cm -2 ), a quantity that is two to three times lower than what was observed by satellite measurements during two massive pollution episodes in the 1980s. Based on the smaller isolatable emissions coming from St. Louis, this quantity is not unreasonable, but may also reflect the reduction of photochemical ozone production due to the implementation of emission controls that have gone into effect in the past few decades.