Abstract

The Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) / Formosa Satellite 3 (FORMOSAT-3) is a new six-satellite radio occultation (RO) mission that was successfully launched in mid- April, 2006. An important feature of the COSMIC constellation is that immediately afte... Show moreThe Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) / Formosa Satellite 3 (FORMOSAT-3) is a new six-satellite radio occultation (RO) mission that was successfully launched in mid- April, 2006. An important feature of the COSMIC constellation is that immediately after launch, the six satellites were clustered together in one orbit. During the first months after the launch the separation between each satellite pair was about 1-2 s in time (about 10 km along the orbit) and is gradually increasing with time. This small separation allowed for closely collocated occultations from one GPS satellite with almost parallel occultation planes. Thus, the COSMIC cluster mode gave a unique opportunity to estimate the precision of RO. This presentation will show an RMS difference of refractivity between 10 and 20 km altitude of less than 0.2% (for tangent point separations less than 10km), which is approximately twice better than previous estimates. Additional results will also be presented that consider variations of RO precision due to altitude, latitude, local time, tangent point separation distance, and near real-time versus post-processed analyses. Show less