Earth's Gravity Field Derived from Grace Satellite Tracking Data

An Earth's gravity field model IGGGRACE01S has been derived from 141 days of GRACE tracking data, including K-band, accelerometer, satellite orbit data. The model resolves the geoid with an accuracy of about 0.012m at a resolution of 500km half-wavelength, it improves the accuracy of the gravity field model in the long- to medium-wavelength part ( < 80 degree) than pre-CHAMP model. Comparing the coefficients of IGGGRACE01S, EIGEN-GRACE02S, EIGEN-CHAMP03S, and EGM96 models, the result shows that the coefficients of IGGGRACE01S are close to those of EIGEN-GRACE02S, and much different to those of the other two models. Comparing the geoid undulations and gravity anomalies derived from the above-mentioned models, the results indicate that the IGGGRACE01S solution is close to EIGEN-GRACE02S solution, and there exist large differences between IGGGRACE01S and EGM96 in Antarctica region. Comparing the gravity anomalies derived from IGGGRACE01S (72 degree) with NIMA gravity anomalies data (2.5 degrees x 2.5 degrees), the standard deviation is 4.8 mGal in China land region.