On the improvement of mass load inversion with GNSS horizontal deformation : a synthetic study in Central China

Abstract

We carry out synthetic experiments of mass load inversion using Global Navigation Satellite System (GNSS) vertical and horizontal displacements in Central China. Using two synthetic mass load models from a checkerboard mass distribution and a more realistic distribution derived from the Gravity Recovery and Climate Experiment (GRACE) observations, the inverted mass changes are determined based on the load theory and then compared with the known mass-change inputs. We find that the combination of horizontal displacements with the commonly used vertical displacements significantly improves the inversion results when the number of sites is larger than one third of the number of total grids with relatively uniform distribution over the region. Synthetic tests demonstrate that data from the Crustal Movement Observation Network of China, including the total number of GNSS sites, spatial distribution, and precision, are sufficient to infer the annual amplitudes of mass changes in the region with comparable spatial resolution as that of GRACE observations. For the current precision level of the GNSS surface displacements (3.0 mm in the vertical and 1.0 mm in the horizontal components), including horizontal displacements leads to ∼10% improvement in mass inversion, compared to using vertical displacements only. With a higher precision level of 0.50 and 0.17 mm (for vertical and horizontal components, respectively), an improvement of ∼20% can be achieved.