Impact of moisture flux convergence and soil moisture on precipitation: a case study for the southern United States with implications for the globe

Jiangfeng Wei, Hua Su, Zong-Liang Yang

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95 Scopus citations


Interactions between soil moisture, evapotranspiration (ET), atmospheric moisture fluxes and precipitation are complex. It is difficult to attribute the variations of one variable to another. In this study, we investigate the influence of atmospheric moisture fluxes and land surface soil moisture on local precipitation, with a focus on the southern United States (U.S.), a region with a strong humidity gradient and intense moisture fluxes. Experiments with the Weather Research and Forecasting model show that the variation of moisture flux convergence (MFC) is more important than that of soil moisture for precipitation variation over the southern U.S. Further analyses decompose the precipitation change into several contributing factors and show that MFC affects precipitation both directly through changing moisture inflow (wet areas) and indirectly by changing the precipitation efficiency (transitional zones). Soil moisture affects precipitation mainly by changing the precipitation efficiency, and secondly through direct surface ET contribution. The greatest soil moisture effects are over transitional zones. MFC is more important for the probability of heavier rainfall; soil moisture has much weaker impact on rainfall probability and its roles are similar for the probability of intermediate-to-heavy rainfall (>10 mm day−1). Although MFC is more important than soil moisture for precipitation over most regions, the impact of soil moisture could be large over certain transitional regions. At the submonthly time scale, the African Sahel appears to be the only major region where soil moisture has a greater impact than MFC on precipitation. This study provides guidance to understanding and further investigation of the roles of local land surface processes and large-scale circulations on precipitation.
Original languageEnglish (US)
Pages (from-to)467-481
Number of pages15
JournalClimate Dynamics
Issue number1-2
StatePublished - Apr 14 2015
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-05-31
Acknowledgements: We thank the anonymous reviewers for their insightful comments on the manuscript and Drs. Robert Dickinson, Bing Pu, and Bo Sun for their suggestions on an early draft. The research was conducted with financial support from the Jackson School of Geosciences at UT-Austin, King Abdullah University of Science and Technology, and NASA (NNX12AJ51G).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

ASJC Scopus subject areas

  • Atmospheric Science


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