We conduct an Observing System Simulation Experiment (OSSE) to test the ability of geostationary satellite measurements of ozone in different spectral regions to constrain surface ozone concentrations through data assimilation. Our purpose is to define instrument requirements for the NASA GEO-CAPE geostationary air quality mission over North America. We consider instruments using different spectral combinations of UV (290-340 nm), Vis (560-620 nm), and thermal IR (TIR, 9.6 ?m). Hourly ozone data from the MOZART global 3-D chemical transport model (CTM) are taken as the "true" atmosphere to be sampled
