Comparison of Satellite-Based Soil Moisture Estimates
and Rainfall Data for a New Mexico Watershed

Background Study Area Data Methods Results & Conclusions

Bias-corrected NEXRAD zonal averages were plotted against change in moisture content between subsequent SMAP grids (Figure 8). The comparison shows a positive correlation between precipitation and changes in soil moisture. The relationship appears to approach a value of approximately 0.12. This is consistent with the author’s experience that soils in the study area are well drained and return to volumetric water contents of less than 20% within hours of a rainfall event.

Figure 8: Chart showing the relationship between the change in soil moisture content and precipitation for three SMAP grids in the study area.

The analysis conducted in this study indicates that satellite-based soil moisture estimates are positively correlated to radar-derived precipitation data that has been bias corrected using rain gage measurements. Bias-corrected NEXRAD precipitation data may therefore provide a viable proxy for soil moisture conditions at a higher spatial resolution compared to SMAP data. Future work should increase the analysis period and spatial extent, include more storm events of larger magnitude, and verify SMAP data against ground measurements of soil moisture.