The versatility of GNSS observations in hydrological studies

Abstract

The Gravity Recovery and Climate Experiment (GRACE) mission makes it possible to infer the land water storage, albeit at a scale of ~300 km. Land water storage can also be inverted from the Global Navigation Satellite System (GNSS) at the cost of a dense network, which is feasible for wealthier nations. Here, the concept of a single GNSS site as a hydrometeorological sensor is explored. Specifically, the crustal displacements and the integrated water vapor (IWV) are used to characterize the 2014–15 drought that jeopardized Southeast Brazil. The crustal displacements as drought indicator confirm the drought persistence during the study period, which agree with GRACE-based values (correlation coefficient [CC] ≥0.49). The IWV and precipitation series are strongly correlated (CC >0.80), whereas during months with daily IWV below approximately 20 mm, there are simultaneities with the absence of rainfall. Furthermore, GNSS-predicted land water storage agrees with GRACE results with normalized root-mean-square differences ≤22.4%.