Can Vertical GPS Displacements Serve As Proxies for Climate Variability in North America?

Abstract

AbstractVertical crustal displacements induced by atmospheric, hydrological, cryospheric, and oceanic load changes are detectable with sub-cm accuracy by precise continuous GPS measurements. Areas subjected to rapid load changes due to ice sheet melt, drought, massive groundwater extraction, or lake level drop, are characterized by a dominant non-linear vertical signal. Here, we investigate possible relations between vertical crustal movements and climate change by analyzing the relations between observed GPS vertical movements, predicted movements, and climatic indices, where we have long GPS time series (>20 years). Applying our analysis to GPS records from western and eastern North America indicates different load change characteristics. In the western US, the seasonal and climatic signals are dominated by hydrological load changes and, consequently, the GPS signal correlates well with the Palmer Severe Drought Index (PSDI) calculated for the same region. However, vertical crustal movements in eastern North America, as detected by long GPS time series, reveal poor correlation with PSDI and other climatic indices. Our results suggest that long continuous GPS observations of vertical crustal displacements primarily driven by climate related changes in water storage can serve as independent measures of regional-scale climate change in some cases, mainly in western north America.