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???????????????????ü????????????????GPS????????λ????????????????????????????????????????????????????????????????Improved??GRACE?????????????????????????????????????????????1????300?????????350 km???????????????????????3.993??10 ^-1 m??????300 km??250 km???????????????????8.770????77.145????????400 km??450 km??????????????????8.718????75.307????2??????50 km???????????????????????3.993??10^-1 m??????110 km??220 km??????????????????1.259????1.395????3????????????Improved??GRACE????????????????????????????????350 km??50 km?????

RESEARCH ON OPTIMAL SELECTION OF ORBITAL PARAMETERS IN IMPROVED-GRACE SATELLITE GRAVITY MEASUREMENT MISSION

The optimal selection of orbital parameters in the future Improved-GRACE satellite gravity measurement mission in China is carried out by using the combined model of cumulative geoid height errors influenced by the intersatellite range-rate error of interferometric laser ranging system, orbital position and velocity errors of GPS receiver and nonconservative force error of accelerometer based on the improved semi-analytic method. The simulated results show as follows.Firstly, at degree 300, cumulative geoid height error is 3.993×10~(-1) m at 350 km orbital altitude, the accuracies are improved respectively 8.770 times and 77.145 times at 300 km and 250 km compared with that at 350 km orbital altitudes, and the accuracies are decreased respectively 8.718 times and 75.307 times at 400 km and 450 km compared with that at 350 km orbital altitudes.Secondly, cumulative geoid height error is 3.993×10~(-1) cm as using 50 km intersatellite range, and the accuracies are reduced respectively 1.259 times and 1.395 times using 110 km and 220 km compared with that using 50 km intersatellite ranges.Finally, the optimal designs of average orbital altitude 350 km and mean intersatellite range 50 km are suggested in the future first Improved-GRACE gravity satellite in China.