2006 JCSDA Seminars

The atmospheric limb sounding technique making use of radio signals transmitted by the Global Position System (GPS) has emerged as a promising approach for global atmospheric measurements. As demonstrated by the proof-of-concept GPS Meteorology (GPS/MET) experiment and more recently by the CHAMP and SAC-C missions, the GPS radio occultation (RO) sounding data are shown to be of high accuracy and high vertical resolution. On 15 April 2006, the joint U.S.-Taiwan COSMIC/FORMOSAT-3 mission, a constellation of six microsatellites, was launched into a 500 km polar orbit from the Vandenberg Air Force Base. These satellites are being deployed to their final orbits at 800 km, which would take about a year. During the early phase of the deployment, the satellites are closely located. This offers a unique opportunity to examine the precision of the GPS RO measurements.

Since mid-August, COSMIC/FORMOSAT-3 has been providing large number (averaging ~1,350 GPS RO soundings per day, and at times exceeding 1,600 GPS RO soundings per day) of GPS radio occultation (RO) soundings to support the research and operational communities. The number of GPS RO soundings will be increased as the satellites are further separated and deployed into their final orbits. Preliminary evaluation study has shown that the GPS RO data from COSMIC/FORMOSAT-3 are of better quality than those from the previous missions. Several global operational centers (e.g. NCEP, ECMWF, CMC and UKMO) have already started testing the COSMIC/FORMOSAT-3 data for operational use, and have already reported encouraging results. The COSMIC/FORMOSAT-3 data have been shown to be very useful for evaluating weather prediction and ionospheric models. With the ability to penetrate deep into the lower troposphere with the advanced open-loop tracking technique, FORMOSAT-3/COSMIC data have shown capability to detect tropical atmospheric boundary layer. Such information is very useful for weather prediction and climate studies. This presentation will review the status of the COSMIC/FORMOSAT-3 mission, and present highlights of scientific research making use of GPS RO observations obtained over the first six months of the mission.

abstract TBD