The Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) mission dramatically increases the spatial and temporal coverage of the Global Positioning System (GPS) radio occultation (RO) data over existing missions on a real-time basis and thus provides an opportunity for pre-operational impact studies of the RO observations for monthly or longer periods. To understand the possible roles of the COSMIC data in improving the weather analysis and forecasting requires studies of month-long duration over different geographical domains. This would allow us to gain insights on when, where, and how the COSMIC data complement existing observation systems.

The NCAR Data Assimilation Testbed Center (DATC) performed a few month-long tests of the COSMIC RO data assimilation for different applications, including domains in southeast Asia, northeast Asia, and Antarctica. In these tests, the Weather Research and Forecasting (WRF) Model is used, together with its WRF-VAR variational data assimilation system. The four-time-per-day weather forecasts up to 72 hours with and without the assimilation of COSMIC data are compared and verified against corresponding profiles from conventional data (e.g., radiosonde), the COSMIC data, and the Atmospheric Infrared Sounder (AIRS) data. The forecasts are also verified against selected analyses.

The multi-domain applications enable the DATC to assess the performance of the WRF and WRFVAR model system and to examine the impacts of the COSMIC data over different geographical areas and with different weather systems. The results provide a rational and scientific basis for operational implementation of COSMIC RO data assimilation in support of short-term weather forecasts.

This presentation will first introduce the current work at the NCAR DATC. Then the individual impact studies of the COSMIC data in different domains will be presented. Finally, the possible role of the COSMIC data from a global prospective will be discussed.