Geocentre variation from laser tracking of LAGEOS12 and loading data Original Researc

Variation in the geocentre is a response to mass redistribution of the solid earth, oceans, atmosphere and hydrosphere. Station coordinates of laser rangers have been determined from tracking of LAGEOS 12 for 1993–2001 in weakly constrained solutions. A Helmert transformation yielded an annual geocentre variation of about 3–4 mm along the X and Y axis and 5 mm along the Z axis. The geocentre can also be estimated from geophysical data including surface atmospheric pressure, continental water levels and ocean mass. These geophysical estimates are compared against the satellite derived solution. The geophysical data is used in a comprehensive examination of the annual mass redistribution in terms of geocentre variation and elastic Earth deformation for station coordinates and orbital perturbations due to the annual variation in the gravity field harmonics.