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An Estimation of the Effect of Soil Moisture on Subsequent Precipitation Using the SMOS Soil Moisture Product
  • Joshua Taylor,
  • Guido Salvucci
Joshua Taylor
Boston University

Corresponding Author:[email protected]

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Guido Salvucci
Boston University
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Abstract

The nature of the relationship between soil-moisture and subsequent precipitation is debated. Past studies have indicated that it varies by location, but there have been disagreements on feedback sign, strength and statistical significance over the same locations even while using the same data sets due to differences in statistical approaches. Here we re-evaluate estimates of feedback strength using Granger causality (following Tuttle and Salvucci 20016) for SMOS and AMSR-2soil moisture products and find that there is evidence both of there being a positive feedback over the entire nation (SMOS) and of there being a west-to-east gradient of positive to negative values (AMSR-2, similar to what was found by Tuttle). This project has demonstrated that differences arise using identical statistical estimation techniques with different satellite estimates of soil moisture. The passive microwave AMSR-E and AMSR-2 data produce a gradient of positive to negative impact factors across the U.S. while the SMOS data set yields a mostly positive impact factor over the entirety of the U.S. Here we explain this discrepancy by noting that the areas where the sign of the impact differ are areas where the soil moisture perturbations of SMOS and AMSR-2 are anticorrelated, and also that these areas coincide with areas of high vegetation cover, which are well known to challenge remote sensing estimates of moisture.