重力卫星五年运行对求定地球重力场模型的进展和展望

对近年升空的CHAMP和GRACE和将于2007年升空的GOCE卫星在测定地球重力场方面的技术特点和初步成果进行了回顾、比较和评估。并对它们今后在静态和动态的地球重力场构模方面可能的进展作一展望。现在只用一颗重力卫星的轨道摄动数据，就可以以前所未有的可靠性和精确性来求定地球重力场的长波和部分中波。如CHAMP重力卫星的33个月数据所求定的地球重力场模型,相对于曾利用多颗卫星资料所推算的GR1M5 S1重力场模型,在长波方面的精度和可靠性都有很大改善。而GRACE重力卫星的 110天数据所导出成果的空间分辨率，又优于CHAMP的33个月的数据成果。GRACE卫星还有一个重要任务，就是测定重力场非潮汐的短期性或准实时的变化。还介绍了新发表的一个联合地球重力场模型EIGEN CG03C, 360完全阶次，分辨率约30′。CG03C同CHAMP/GRACE以前的重力场模型比较，在400 km波长的精度方面改善了一个量级，大地水准面的精度改善了3 cm，重力异常的精度改善了0.4 mgal。

Review and Prospect for the Earth Gravity Field Determination with Gravity Satellites in the Past Five Years

The technical behaviors and preliminary results in the global gravity field determination obtained from the gravity satellites CHAMP, GRACE and GOCE which will be launch in the near future, are reviewed, compared and summarized. The possible development for the construction of static and kinematic global gravity model based on the observation data of these gravity satellites are also given in the paper. A CHAMP only global gravity field model derived from 33 months of mission data is much better than GRIM5-S1, which was derived from the pre-CHAMP multi- satellite data. The resolution for the result derived from GRACE 110days data is better than that derived from CHAMP mission data mentioned above. There is another task for the GRACE mission, i.e., to determine the real or near real time non tidal variation in the global gravity field. A new combined earth gravity model EIGEN-CG03C, 360 order and degree, 30’ resolution is introduced in the paper. In comparison with the former earth gravity model the accuracy of CG03C is improved by one magnitude in the 400 m wave length, that of geoid is improved by 3 cm, and that of surface gravity anomaly is improved by 0.4 mgal.