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Error Propagation in Microwave Soil Moisture and Vegetation Optical Depth Retrievals
Andrew F Feldman1, David Chaparro1, Dara Entekhabi2
1Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
|January 10, 2022
Summary
Satellite-derived vegetation optical depth (VOD) is less robust to errors than soil moisture. Moderate regularization improves VOD accuracy and reduces soil moisture-VOD coupling for global water relation studies.
Area of Science:
- Earth Science
- Remote Sensing
- Hydrology
Background:
- Satellite soil moisture and vegetation optical depth (VOD) are crucial for studying global soil-plant water relations.
- Joint estimation of soil moisture and VOD can lead to error compensation, confounding studies.
- Quantifying error propagation from satellite microwave measurements into soil moisture and VOD is critical.
Purpose of the Study:
- To quantify how satellite microwave measurement errors affect soil moisture and VOD.
- To investigate if VOD reflects *in situ* plant physiology.
- To assess if VOD regularization reduces errors without obscuring true vegetation dynamics.
Main Methods:
- Analysis of error propagation in joint soil moisture and VOD estimation.
- Evaluation of VOD regularization techniques, specifically time-constrained VOD.
- Comparison of regularized and unregularized VOD and soil moisture under various conditions, including post-rainfall events.
Main Results:
- VOD is less robust to measurement errors than soil moisture during joint estimation.
- Moderate VOD regularization significantly reduces VOD errors and spurious soil moisture-VOD coupling.
- Regularized VOD variations align better with simulated true VOD and show reduced error signatures after rainfall.
Conclusions:
- Moderately regularized VOD is recommended for large-scale soil-plant water relation studies.
- Regularization effectively suppresses noise and spurious coupling without removing the physical vegetation signal.
- This approach enhances the reliability of satellite-derived VOD for hydrological and ecological research.
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