Contribution of LARES SLR Data to Co-estimated Earth Geopotential Coefficients

Abstract

The Satellite Laser Ranging (SLR) processing at the Astronomical Institute of the University of Bern (AIUB) is currently extended from the geodetic satellites LAGEOS-1/2 and Etalon-1/2 to also include LARES. The orbits are determined in 7-day arcs together with station coordinates, low-degree spherical harmonic (SH) coefficients of the Earth’s gravity field, Earth Rotation Parameters (ERP), geocenter variations and range biases for selected stations. Due to the lower orbital altitude, LARES experiences a more variable environment such that the orbit parametrization has to be adapted. In this paper, we present SLR solutions for 5 years with different orbit parametrizations for LARES, i.e., LARES 7-day arcs are either determined from one set of orbit parameters and stochastic pulses at fixed time-intervals, or by stacking of seven daily arcs with continuity conditions at the day boundaries, so-called long-arcs. Including LARES does slightly improve the ERP and does not degrade the quality of the estimated SH coefficients and station coordinates. Additionally, it allows co-estimating the SH coefficient C30 and further low-degree SH coefficients.