Type: Article
Title: Evaluating long-term water storage trends in small catchments and aquifers from a joint inversion of 20 years of GRACE/GRACE-FO mission data
Authors: Kvas, Andreas
Boergens, Eva
Dobslaw, Henryk
Eicker, Annette 
Mayer-Guerr, Torsten
Güntner, Andreas
Issue Date: Feb-2024
Keywords: Satellite geodesy; Time variable gravity; Hydrology
Abstract: 
More than 20 yr of measurement data of the gravity missions GRACE (Gravity Recovery And Climate Experiment) and GRACE-FO (GRACE-Follow-On) allow detailed investigations of long-term trends in continental terrestrial water storage (TWS). However, the spatial resolution of conventional GRACE/GRACE-FO data products is limited to a few hundred kilometres which restrains from investigating hydrological trends at smaller spatial scales. In this study GRACE and GRACE-FO data have been used to calculate TWS trends with maximized spatial resolution. Conventionally, GRACE/GRACE-FO is presented as a series of either unconstrained gravity fields post-processed with spatial low pass filters or constrained inversions commonly known as Mascon products. This paper demonstrates that both approaches to suppress spatially correlated noise are mathematically equivalent. Moreover, we demonstrate that readily inverting all available sensor data from GRACE/GRACE-FO for a single TWS trend map, together with annual variations and a mean gravity field, provides additional spatial detail not accessible from the standard products. The variable trade-off between spatial and temporal resolution as a unique feature of satellite gravimetry allows for gravity products that are tailored towards specific geophysical applications. We show additional signal content in terms of long-term water storage trends for four dedicated examples (Lake Victoria, Northwest India, Bugachany Reservoir and High Plains Aquifer) for which external information from other remote sensing instruments corroborates the enhanced spatial resolution of the new mean-field trend product.
Subject Class (DDC): 550: Geowissenschaften
HCU-Faculty: Geodäsie und Ausgleichungsrechnung 
Journal or Series Name: Geophysical Journal International 
Volume: 236
Issue: 2
Start page: 1002
End page: 1012
Publisher: Oxford University Press
ISSN: 0956-540X
Publisher DOI: 10.1093/gji/ggad468
URN (Citation Link): urn:nbn:de:gbv:1373-repos-12164
Directlink: https://repos.hcu-hamburg.de/handle/hcu/944
Language: English
Creative Commons License: https://creativecommons.org/licenses/by/4.0/
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