Strategies to remove hydrological effects in continuous gravity time series

Abstract

Multi-annual gravity time series offer a unique, noninvasive way to monitor mass redistributions within the Earth. However, for non-hydrological purposes, gravity time series must be corrected from hydrological effects to properly quantify mass redistribution involved in other geodynamic processes, such as volcanic activities or sedimentation processes. Such a hydrological correction remains challenging. The objective of this work is to investigate various ways to remove hydrological effects from a 11-years long gravity time series acquired by a superconducting gravimeter (SG) located at the Onsala Space Observatory (Sweden). For that we use hydrological loading corrections distributed by the EOST loading service, and local in situ groundwater level measurements. The most efficient approaches correct up to 89% of the seasonal component of the hydrological signal in the gravity series. On the other hand, for that specific site, we observe local water redistributions at shorter time scales, hours to few days, have a negligible influence on the gravity time series.