J20.4 Local versus Remote Soil Moisture Contributions to Near-Surface Temperature Variability

Tuesday, 9 January 2018: 9:15 AM
Room 18A (ACC) (Austin, Texas)
Randal D. Koster, NASA GSFC, Greenbelt, MD; and S. Schubert, H. Wang, and Y. Chang

Soil moisture variations have a straightforward impact on overlying air temperatures – wetter soils can induce higher evaporative cooling of the soil and thus, locally, cooler temperatures overall. Not known, however, is the degree to which soil moisture variations can affect remote air temperatures through their impact on the atmospheric circulation. In this talk we describe a two-pronged analysis that addresses this question. In the first segment, an extensive ensemble of NASA/GSFC GEOS-5 atmospheric model simulations is analyzed statistically to isolate and quantify the contributions of various soil moisture states, both local and remote, to the variability of air temperature at a given local site. In the second segment, the relevance of the derived statistical relationships is evaluated by applying them to observations-based data. Results from the second segment suggest that the GEOS-5-based relationships do, at least to first order, hold in nature and thus may provide some skill to forecasts of air temperature at subseasonal time scales, at least in certain regions.
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