89th American Meteorological Society Annual Meeting

Monday, 12 January 2009
Field Scale Variability in Soil Temperature and Moisture in Seasonally Frozen Ground
Hall 5 (Phoenix Convention Center)
Tushar Sinha, North Carolina State University, Raleigh, NC; and K. A. Cherkauer
Soil moisture is a major controlling variable in the partitioning of precipitation into runoff, infiltration, surface storage and evapotranspiration. Its availability affects how surface energy fluxes are converted into latent heat and sensible heat fluxes, influencing surface temperatures. Soil water helps in determining the thermal conductivity and thermal diffusivity of the soil especially as the freezing of water in the soil leads to formation of soil ice, which increases the thermal conductivity of soil by as much as four times. During the freezing process, water content varies from point to point affecting thermal conductivity, which in turn changes the temperature distribution in the soil. Therefore, it is important to understand the interactions of soil moisture and temperature that governs soil frost formation during winter season.

In the present study, the spatial and temporal variability of winter soil moisture and soil temperature under different land cover types are examined. Multiple sites have been monitored for the winter seasons of 2005-2006 and 2006-2007 at the Agronomy Center for Research and Education (ACRE) in central Indiana. A point simulation of a large scale Variable Infiltration Capacity (VIC) model is used to evaluate the model performance in estimating the water and energy balance dynamics for the same time period as the field observations. Model predicted variables such as soil temperature, soil ice content, freeze-thaw depths and snow accumulation are analyzed spatially and temporally under different land cover characteristics. The effect of temporal resolution including hourly, daily, and monthly time scales are compared to study spatial variability in soil moisture and soil temperature in frozen ground.

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