HR: 0800h
AN: G51B-0081    [Abstracts]
TI: Orbit and Gravity Determinations Using ROCSAT3/COSMIC GPS Data: Status 2004
AU: * Hwang, C
EM: hwang@geodesy.cv.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AU: Wang, C
EM: wcg@geodesy.cv.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AU: Hwang, L
EM: shinn@ccit.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AU: Lin, T
EM: ltl@geodesy.cv.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AU: Lee, Y
EM: yslee@geodesy.cv.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AU: chang, L
EM: lschang@geodesy.cv.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AU: Hsu, S
EM: rice@geodesy.cv.nctu.edu.tw
AF: Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, 300 Taiwan
AB: The ROCSAT3/COSMIC (RC) mission is scheduled to be launched in late 2005 and contains a geodetic element in the mission. Each of the six satellites of RC is equipped with a POD GPS­@antenna which yields data for precise orbit and gravity determinations. In view of the large number of satellites and orbital planes, simple satellite­Ýs simple geometry (cylindrical) and a long life span (expected 5 years), the geodetic results from RC are particularly suited for static and time-varying gravity research. This paper reports the status of our geodetic research related to the RC mission as of 2004. A computer program package, called CTODS, is developed for precise orbit and gravity determination. In CTODS, satellite perturbing force models are based on the IERS2000 standards and the results are validated using the results from NASA/GSFC­Ýs GEODYN II program. A one-step method, based on a GPS-preprocessing package and GEODYN II, was used to determine CHAMP orbit and gravity. In a two-step approach, one year of CHAMP precise positions, which were determined using a pure kinematic method, were used as satellite tracking data to compute weekly gravity harmonic coefficients. Simulation results using an analytical orbit theory show that RC-recovered gravity contains prominent gravity changes during the 1997-1998 El Niño event.
DE: 9800 GENERAL OR MISCELLANEOUS
DE: 1200 GEODESY AND GRAVITY
DE: 1299 General or miscellaneous
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting