Bernese GPS Software Version 5.0 - Bernese GNSS Software

15. Estimation of Satellite Orbits and Earth Orientation Parameters
Figure 15.6: Options for defining the setup for Earth orientation parameters in ADDNEQ2.
15.4.4 Estimation of Geocenter Coordinates
Because satellites are sensitive to the center of mass of the total Earth (geocenter), satellite
geodetic techniques are in principle sensitive to motions of the center of mass with respect
to the origin of a crust-fixed reference frame. Such motions are expected due to mass displacements
in the oceans, the atmosphere, and the interior of the Earth as well as from
surface deformations originating from loading effects.
In the Bernese GPS Software, Version 5.0 , geocenter coordinates may be estimated in
programs GPSEST and ADDNEQ2. It has, however, to be remarked that the sensitivity of
GNSS to geocenter motions is low due to correlations of these parameters with radiation
pressure modeling parameters.
In program GPSEST the estimation of geocenter coordinates is initiated by enabling the
corresponding checkbox “Geocenter coordinates” in panel “GPSEST 5.2: Setup of Parameters and
Pre-Elimination 2”. The menu system then displays panel “GPSEST 6.14: Geocenter Coordinates”
which allows to switch on and to constrain the estimation for each coordinate component
individually. Geocenter coordinates are modeled in the Earth-fixed frame as constant values
for the entire session.
Program GPSEST does not write a geocenter output file but includes the parameters into the
output normal equation file for further analysis with ADDNEQ2 and generates the following
output in the general program output file (values in meters):
Page 324 AIUB