Extracting seasonal deformations of the Nepal Himalaya region from vertical GPS position time series using Independent Component Analysis

Seasonal variations in vertical GPS time series are mainly caused by the Earth surface mass loading plus bedrock thermal expansion and GPS systematic errors. Relevant surface mass loading phenomena include atmospheric pressure, continental water storage, and non-tidal ocean loading. In regions with significant water storage variations, the hydrological effect makes the greatest contribution to Earth surface seasonal deformation. In this paper, we extract the various seasonal deformations from GPS time series of 17 stations in the Nepal Himalaya region using a blind source separation tool, the Independent Component Analysis (ICA). The vertical displacement components extracted by ICA showed strong correlations with modeled deformation induced by atmospheric and hydrological loading, indicating that independent components may represent different loading effects. Considering the wide application of GRACE in detecting hydrological deformation, we make a comparison between GRACE-derived displacements and the independent displacements contained in GPS. The results show ICA is effective in extracting atmospheric and hydrological deformation.