Comparing variance of signal contained in the most recent GRACE solutions

Abstract

Gravity Recovery and Climate Experiment (GRACE) mission data is widely usedin various fields of science. GRACE explored changes of the gravity field regularly fromApril 2002 to June 2017. In the following research, we examine variance of signal containedin two different formats of GRACE data: standard spherical harmonics and mass concentra-tion blocks (so-called “mascons”) solutions, both provided in the most recent releases. Forspherical harmonics-based solution, we use monthly gravity field solutions provided up todegree and order (d/o) 96 by three different computing centers, i.e. the NASA’s Jet Propul-sion Laboratory (JPL), the German Research Center for Geosciences (GFZ) and the Centerfor Space Research (CSR). For the mass concentration blocks, we use values of total waterstorage provided by the CSR, JPL and the Goddard Space Flight Center (GSFC) computingcenters, which we convert to spherical harmonic coefficients up to d/o 96. We show thatusing the anisotropic DDK3 filter to smooth the north-south stripes present in total waterstorage obtained from standard spherical harmonics solution leaves more information thancommon isotropic Gaussian filter. In the case of mascons, GSFC solution contains muchmore information than the CSR and JPL releases, relevant for corresponding d/o. Differ-ences in variance of signal arise from different background models as well as various shapeand size of mascons used during processing of GRACE observations.

Keywords

• grace
• degree variance
• spherical harmonic coefficients
• mass concentra-tion blocks