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GPS radio occultation with COSMIC



FORMOSAT-3/COSMIC is a joint Taiwan-U.S. project. The scientific foundation for FORMOSAT-3/COSMIC is the radio occultation (limb sounding) technique which was developed by the Jet Propulsion Laboratory (JPL) and Stanford University in the late 1960s to study planetary atmospheres.

The FORMOSAT-3/COSMIC constellation will be launched in March 2006, and is expected to last at least for five years. Over the first year, the satellites will be gradually boosted from their initial orbit of 400 kilometers to the final orbit of roughly 800 kilometers, conducting important geodetic/gravity experiments during this phase.

The FORMOSAT-3/COSMIC will consist of

  1. the six spacecraft each with three instruments, including GPS radio occultation receiver, tiny ionospheric photometer, and tri-band beacon
  2. a satellite operations control center (SOCC) at the National SPace Organization (NSPO) in Hsin-Chu, Taiwan,
  3. a COSMIC Data Analysis and Archive Center (CDAAC) in Boulder, Colorado, and
  4. a global ground fiducial network (built upon existing NASA and international fiducial networks).

Data are freely available to the international scientific community in near real time. The total mission cost for FORMOSAT-3/COSMIC is approximately $100 M U.S. dollars, with which approximately 80% was contributed by NSPO in Taiwan. The remaining 20% was provided by U.S. agencies, including NSF, NASA, NOAA, US Air Force, US Navy, and STP.

FORMOSAT-3/COSMIC not only has great value for weather, climate, and space weather research and forecasting, but also geodesy and gravity research and other applications. The FORMOSAT-3/COSMIC high vertical and lower horizontal resolution measurement will complement the high horizontal and lower vertical resolution measurements of existing and planned global meteorological satellites. Data assimilation schemes are also being developed to effectively integrate the COSMIC data into existing operational weather forecasting models. FORMOSAT-3/COSMIC will also complement a variety of related GPS missions, including CHAMP, SAC-C, and GRACE.

GFZ activities related to FORMOSAT-3/COSMIC

The activities of GFZ scientists related to COSMIC are manifold. Before the launch they were involved in the preparation of the mission by provision of CHAMP data to prepare the COSMIC processing centers. In addition several joint RO related studies with Taiwan and U.S. scientist were carried out to exchange and enhance the RO expertise of the community. FORMOSAT-3/COSMIC data are currently used to improve orbit and occultation processing algorithms at GFZ. In addition the analysis results from UCAR increase the data base for various climatological investigations at GFZ (Tropopause, Gravity waves, ionospheric irregularities).


WICKERT, J., Michalak, G., Schmidt, T., Beyerle, G., Cheng, C.Z., Healy, S.B., Heise, S., Huang, C.Y., Jakowski, N., Köhler, W., Mayer, C., Offiler, D., Ozawa, E., Pave-lyev, A.G., Rothacher, M., Tapley, B., Arras, C., 2008: GPS radio occultation: Results from CHAMP, GRACE and FORMOSAT-3/COSMIC. Terr. Atmos. and Oceanic Sci., 2009.

WICKERT, J., T. Schmidt, G. Michalak, S. Heise, C. Arras, G. Beyerle, C. Falck, R. Koenig, D. Pingel, and M. Rothacher, GPS radio occultation with CHAMP, GRACE, SAC-C, TerraSAR-X, and COSMIC: Brief review of results from GFZ, Springer book, OPAC-3 workshop, 2008.

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