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The role of soil moisture in warm-season convective precipitation for the Midwestern United States Corn Belt

Authors: Connor Chapman*, Pennsylvania State University Main Campus
Topics: Climatology and Meteorology, Environmental Science, Land Use and Land Cover Change
Keywords: Physical Geography, Climate, Climatology, Soil Moisture, Precipitation, Land Cover
Session Type: Poster
Presentation File: No File Uploaded

The Midwestern United States Corn Belt is predominantly croplands interspersed with smaller areas of forest and prairie, and also scattered urban land covers. Climatic studies for many agricultural regions in middle latitudes over about the past fifty years indicate an influence of land cover differences on convective (i.e., locally overturning air) processes, modified by soil moisture content and the larger-scale (synoptic) atmospheric conditions.
Past research demonstrates a relationship between soil moisture and atmospheric humidity, as well as low-altitude air advection (horizontal wind), in determining the spatial and temporal development of convective clouds and rainfall. However, the sign (positive or negative) and intensity of such a relationship remain unclear, as numerous investigations conclude varying results for differing spatiotemporal regimes. This study assesses the relationship between soil moisture, atmospheric humidity, and horizontal wind on a climatological (time-averaged, spatially varying) temporal scale for four locations in the dominantly rain-fed agricultural areas of the Corn Belt. Data from the Soil Climate Analysis Network (SCAN) and Earth Science Research Laboratory (ESRL) are used for the nine growing seasons (May-September) of 2011-2019 to identify configurations of soil moisture/atmospheric humidity/low-altitude air advection that are conducive to convective precipitation development.
Results to date indicate a preference for relatively low or high soil moisture states on days with high humidity and strong, southerly low-altitude winds comprising a low-level jet for the development of convective precipitation. These results are likely explained by the varying influence of sensible and latent heat fluxes according to land cover type on lower atmosphere thermodynamics.

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