OCO-3

Orbiting Carbon Observatory-3 (OCO-3) is NASA’s International Space Station instrument measuring column-integrated atmospheric carbon dioxide and solar-induced chlorophyll fluorescence. Its two-axis pointing mirror supports nadir, glint, validation-target and Snapshot Area Mapping modes; snapshot scans can sample contiguous areas roughly 80 by 80 km across cities or ecosystems during a single overpass. The ISS orbit supplies observations at changing local times of day, supporting studies of daily variations in carbon exchange and plant activity. Clouds and aerosols affect usable observations. Column concentrations and fluorescence provide evidence for carbon-cycle analysis; estimating surface sources and sinks requires additional interpretation.