Analysis of GRACE Range-rate Residuals with Emphasis on Reprocessed Star-Camera Datasets

Abstract:

Since March 2002 the two GRACE satellites orbit the Earth at rela-
tively low altitude. Determination of the gravity field of the Earth including its
temporal variations from the satellites’ orbits and the inter-satellite measure-
ments is the goal of the mission. Yet, the time-variable gravity signal has not
been fully exploited. This can be seen better in the computed post-fit range-rate
residuals. The errors reflected in the range-rate residuals are due to the differ-
ent sources as systematic errors, mismodelling errors and tone errors. Here, we
analyse the effect of three different star-camera data sets on the post-fit range-
rate residuals. On the one hand, we consider the available attitude data and
on other hand we take the two different data sets which has been reprocessed
at Institute of Geodesy, Hannover and Institute of Theoretical Geodesy and
Satellite Geodesy, TU Graz Austria respectively. Then the differences in the
range-rate residuals computed from different attitude dataset are analyzed in
this study. Details will be given and results will be discussed.