Gravity Field Dynamics and Terrestrial Water Storage

The Earth’s gravity field is shaped not only by its solid structure but also by the movement and storage of fluids at the surface and near‐surface. Mass redistributions associated with snow, ice, soil moisture and groundwater alter the gravitational potential, producing measurable signals on spatial scales from tens to thousands of kilometres. Terrestrial water storage (TWS) refers to the total water held in all land reservoirs, including surface water, soil moisture, snow and ice, and groundwater. Time variations in TWS influence sea level, regional climate, natural hazards and water resources. Satellite gravimetry missions have transformed our ability to observe TWS changes: by tracking the distance between twin satellites, missions such as GRACE and its successor GRACE-FO infer mass anomalies that correspond directly to water gain or loss on the continents. Complementary geodetic techniques, notably global navigation satellite systems (GNSS), detect crustal deformation induced by loading and unloading of water masses, thereby providing higher‐resolution insights into local hydrological processes. These observations are integrated with hydrological models and machine‐learning reconstructions to extend time series beyond the satellite era, to attribute drivers of variability and to predict future trends under changing climate and human pressures. The interplay between gravity field dynamics and terrestrial water storage underpins a global monitoring framework that supports water security, flood forecasting, drought assessment and the evaluation of climate model projections.

Research from Nature Portfolio

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Research from all publishers

Recent studies employing GNSS and probabilistic principal component analysis have enhanced understanding of vertical crustal displacements caused by groundwater mass changes. By removing contributions from non-groundwater water compartments using global hydrology models, researchers demonstrated coherent spatio-temporal patterns between GPS-derived and GRACE-based estimates, revealing multi-year cycles and the capacity of GNSS to resolve local groundwater variability. A second thread of research has harnessed machine-learning algorithms to reconstruct global TWS back to the 1940s at high spatial resolution. This approach integrates climatic, land-cover and vegetation predictors to produce monthly TWS anomaly fields that align closely with GRACE observations and independent river-basin budgets, offering a century-long perspective on hydrological variability and extremes. A third avenue of investigation has compared observed TWS trends from satellite gravimetry with those simulated by the latest climate models. Such work has uncovered systematic biases—most notably a model consensus on drying in the Amazon that conflicts with observed wetting—and emphasised the necessity of sustained gravity-field observations for robust climate‐change assessments.

Gravity Field Dynamics and Terrestrial Water Storage publication trend

The graph below shows the total number of articles in gravity field dynamics and terrestrial water storage across all publications each year (not limited to Nature Index journals).

Technical terms

Gravity field: The spatial variation of Earth’s gravitational acceleration resulting from internal density contrasts and surface mass redistribution.

Terrestrial water storage (TWS): The total water contained in all land reservoirs, including snow, soil moisture, groundwater and surface water.

GRACE (Gravity Recovery and Climate Experiment): A satellite mission that measures temporal variations in Earth’s gravity field by tracking inter‐satellite distance changes.

Mascon: A mass concentration element used in gravity data processing to represent regional mass anomalies.

GNSS (Global Navigation Satellite System): A constellation of satellites whose signals enable high-precision positioning and detection of Earth surface deformation due to mass loading.

References

1. Studying spatio-temporal patterns of vertical displacements caused by groundwater mass changes observed with GPS. Remote Sensing of Environment (2023).
2. GTWS-MLrec: global terrestrial water storage reconstruction by machine learning from 1940 to present. Earth System Science Data (2023).
3. Observations indicate regionally misleading wetting and drying trends in CMIP6. npj Climate and Atmospheric Science (2024).