Observing System Simulation Experiments with Several Combinations of Radio Occultation Constellations

Global Navigation Satellite Systems (GNSS) Radio Occultation (RO) observations have been assimilated in operational weather centers for almost a decade now. Operational assimilation begun after the launch of the FORMOSAT-3/COSMIC mission in April 2006, consisting of six RO satellites. Originally planned as a 5-year mission, COSMIC is still delivering good-quality RO profiles for operational assimilation. However, the counts are dropping as the constellation ages, and there is thus a need within the community for a follow-on mission. COSMIC-2, the follow-on to COSMIC, will provide ~10,000 profiles/day globally distributed. Commercial options are also becoming important as the need for additional RO profiles increases.

We have conducted several Observing System Simulation Experiments (OSSEs) to evaluate the impact of additional RO observations in weather forecast skill. Several setup configurations were tested and results, as well as the limitations of our experiments, will be discussed during this presentation.