Dissecting soil moisture-precipitation coupling

Authors

  • Jiangfeng Wei,

    Corresponding author
    1. Center for Ocean-Land-Atmosphere Studies, Calverton, Maryland, USA
    2. Now at Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
    • Corresponding author: J. Wei, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78712, USA. (jwei@utexas.edu)

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  • Paul A. Dirmeyer

    1. Center for Ocean-Land-Atmosphere Studies, Calverton, Maryland, USA
    2. Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, Fairfax, Virginia, USA
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Abstract

[1] The ability of soil moisture to affect precipitation (SM-P) can be dissected into the ability of soil moisture to affect evapotranspiration (ET; SM-ET) and the ability of ET to affect precipitation (ET-P). SM-ET is a local process that is relatively easy to quantify, but ET-P includes nonlocal atmospheric processes and is more complex. Here, ET-P is quantified both locally and remotely with a back-trajectory method for water vapor transport, using corrected reanalysis data. It is found that, for SM-P and ET-P, local impact is greater than that from remote for most land areas with significant local impacts. By examining the responses of the three metrics (SM-ET, ET-P, and SM-P) to climate variations over different climate regimes, we show that SM-ET is the principal factor that determines the spatial pattern and variation of SM-P. For climatologically wet regions, SM-ET and SM-P are higher during dry periods, and vice versa for climatologically dry regions. All three metrics show highest values over the transitional zones.

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