Effect of different inter-satellite range on measurement precision of Earth’s gravitational field from GRACE

:The precision of Earth’s gravitational field from GRACE up to degree and order 120 was studied for different inter-satellite ranges using the improved energy conservation principle. Our simulated result shows that; For long wavelength (L ⩽ 20) at degree 20, the cumulative geoid-height error gradually decreased with increasing range, from 0. 052 cm for 110 km to 1. 156 times and 1. 209 times as large for 220 km and 330 km, respectively. For medium-wavelength (100 ⩽ L ⩽ 120) at degree 120, the cumulative geoid-height error decreased from 13. 052 cm for 110 km, to 1. 327 times and 1. 970 times as large for the ranges of 220 km and 330 km, respectively; By adopting an optimal range of 220 ± 50 km, we can suppress considerably the loos of precision in the measurement of the Earth’s long-wavelength and medium-wavelength gravitational field.