Least square estimation of the bias of the measured distance between the two GRACE satellites and production of a new KBRL1B-X files versions based on GPS observations

Gravity Recovery and Climate Experiment (GRACE) satellite gravimetry mission launched in March 2002 based on its twin gravimetric satellites makes application of both High-Low (HL) and Law-Low (LL) gravimetric techniques possible. The LL is based on Satellite-to-Satellite Tracking (SST) via the one way two frequencies K-Band-Ranging between the two GRACE satellites. As a result of combination of LL and HL structures via geodesy community following gravity observables are developed: (1) Potential Difference between the two GRACE satellites based on Line of Sight (LOS) velocity using energy integral method. (2) Projection of the gravitational acceleration difference of the two GRACE satellites along the LOS, using LOS acceleration. The latter observable which can provide finer details is one of the important observation quantities of the GRACE mission. Application of this observable as a boundary data for local and regional modeling of the Earth’s gravity field provides valuable information about short and medium wavelength spectrums of the field.