Application of ERS-2 prare data for orbit determination and gravity field and station coordinate estimation Original Research Article

Three and a half years of ERS-2 PRARE (Precise Range and Range-rate Equipment) observations covering May 1995 – December 1998 have been analyzed for use in ERS-2 orbit determination, gravity field modeling and station coordinate estimation. Including PRARE data in the ERS-2 orbit computation results in significantly more precise and stable orbits. The estimated resulting orbit accuracy is below 5 cm, and seems to approach the TOPEX/POSEIDON orbit accuracy level. The improved orbits result in more accurate dynamic sea surface topography modeling. In addition, it can be shown that the PRARE data contain important information for reducing the gravity field induced ERS orbit error. PRARE data have been used successfully in addition to SLR (Satellite Laser Ranging) observations and radar altimeter crossover differences to reduce the gravity field induced ERS-2 orbit errors. Finally, time series of PRARE station coordinate solutions were produced resulting in realistic velocity estimates. For the stations not located close to plate boundaries excellent agreement was found with predicted velocities using either the NUVEL-1a model or the ITRFʹ94 solution. Special attention was paid to the Neumayer station which is located on an ice sheet. Clear tidal components could be observed in the motion of this station derived from the tracking observations. The analysis of PRARE data has proven PRAREʹs ability for improved orbit determination, gravity field modeling and station coordinate estimation.