Joint Inversion of GNSS and GRACE for Terrestrial Water Storage Change in California

Area of Science:

• Geodesy
• Hydrology
• Remote Sensing

Background:

• Terrestrial water storage change (∆TWS) is crucial for understanding water resources and climate trends.
• Estimating ∆TWS using Global Navigation Satellite System (GNSS) vertical displacements requires dense networks and is prone to non-hydrologic noise.
• The Gravity Recovery and Climate Experiment (GRACE) offers global ∆TWS data but with low spatial resolution.

Purpose of the Study:

• To develop a joint inversion framework combining GNSS and GRACE data for enhanced spatiotemporal ∆TWS mapping.
• To improve the accuracy and spatial resolution of ∆TWS estimates, overcoming limitations of individual methods.
• To better capture long-term trends and seasonal variations in water storage, particularly in data-rich regions like California.

Main Methods:

• Joint inversion of GNSS vertical displacement time series and GRACE ∆TWS data.
• Utilizing continuous wavelet transform for signal decomposition into temporal components (long-term and short-term).
• Accounting for observation errors, data gaps, and non-hydrologic deformation signals in the inversion process.

Main Results:

• The joint inversion framework produces ∆TWS maps with improved spatial resolution compared to GRACE alone.
• Results show regional consistency with GRACE data across various temporal scales.
• The enhanced resolution allows for better differentiation of water mass changes in specific regions, valuable for drought assessment.

Conclusions:

• The joint inversion of GNSS and GRACE data offers a powerful approach for high-resolution ∆TWS estimation.
• This method enhances our ability to monitor water resources and understand hydrological dynamics, especially in tectonically active areas.
• The improved spatiotemporal mapping aids in managing freshwater supplies under changing climate conditions and recurrent droughts.