Download or read book Efficient Global Gravity Field Determination from Satellite-to-satellite Tracking written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: By the middle of this decade, measurements from the CHAMP (CHAllenging of Minisatellite Payload) and GRACE (Gravity Recovery And Climate Experiment) gravity mapping satellite missions are expected to provide a significant improvement in our knowledge of the Earth's mean gravity field and its temporal variation. For this research, new observation equations and efficient inversion method were developed and implemented for determination of the Earth2s global gravity field using satellite measurements. On the basis of the energy conservation principle, in situ (on-orbit) disturbing potential and potential difference observations were computed using data from accelerometer- and GPS receiver-equipped satellites, such as CHAMP and GRACE. The efficient iterative inversion method provided the exact estimates as well as an approximate, but very accurate error variance-covariance matrix of the least squares system for both satellite missions. The global disturbing potential observable computed using 16-days of CHAMP data was used to determine a gravity field solution (OSU02A), is commensurate in geoid accuracy to other gravity models and yields improvement in the polar region at wavelengths longer than 800 km. The annual variation of Earth's gravitational field was estimated and compared with other solutions from satellite laser ranging analysis. The annual geoid change of 1 mm would be expected mostly due to atmosphere, continental surface water, and ocean mass redistribution. The correlation between CHAMP and SLR solutions was 0.6 to approx 0.8 with 0.7 mm of RMS difference. Based on the monthly GRACE simulation, the geoid was obtained with an accuracy of a few cm and with a resolution (half wavelength) of 160 km. However, the geoid accuracy can become worse by a factor of 7 because of spatial aliasing. The approximate error covariance was found to be a very good accuracy measure of the estimated coefficients, geoid, and gravity anomaly. The resulting recovered temporal gravity fields have about 0.2 mm errors in terms of geoid height with a resolution of 670 km. It was quantified that how significant the effects due to the inherent modeling errors and temporal aliasing caused by ocean tides, atmosphere, and ground surface water mass are on monthly mean GRACE gravity estimates.