A decorrelation filter based on the full error covariance of GRACE gravity field solutions

Abstract

We propose a decorrelation filter (noise-reduction filter) constructed by using the full error covariance matrix information of the spherical harmonic solutions derived from the observations of the Gravity Recovery and Climate Experiment (GRACE) mission. To construct the noise-reduction filter, the filter factors are inversely proportional to the eigenvalues of the covariance matrix. Using the designed noise-reduction filter, we can significantly reduce the north-south stripes in monthly GRACE gravity field solutions. Our study shows that the noise-reduction filter can achieve higher signal-to-noise ratio as compared to other filtering methods under consideration, i.e., P 3 M 8 and P 4 M 6 as well as Gaussian smoothing. Using the noise-reduction filter, the estimated mass rates over the entire Antarctica, East Antarctica and West Antarctica (including the Antarctica Peninsula) are -107.38±41.06 Gt/yr, 36.42±14.40 Gt/yr and -147.45±16.78 Gt/yr respectively, consistent with the results from the P 3 M 8 filter and P 4 M 6 combined with Gaussian filter.