A Coupled Soil Moisture and Surface Temperature Prediction Model

Abstract

A model for soil moisture and soil surface temperature prediction for bare soil is considered in this paper. In describing evaporation rate. soil structure and moisture were taken into account as much as possible. Soil moisture prediction was carried out using Sellers? method. Hydraullic properties were determined both known values for the given type of soil and the empirical equations of Clapp and Hornberger. Soil surface temperature prediction were made using the ?force-restore? method. Sensible and latent heat fluxes were determined using a resistance representation taking into consideration atmospheric stability. The model results were compared with some field data of soil temperature and latent and sensible heat fluxes. The agreement between the model-calculated and the observed heat fluxes was fairly good. Soil moisture and temperature prediction were satisfactory, although an excessive drying occurred at the beginning of a five-day simulation period. Some sensitivity analyses were also made. The model formulation of latent heat flux was compared with the formulation of Philip. Tests were made for different values of ?mean temperature? in the restore term. Furthermore, the model is applicable for the calculation of sensible and latent heat fluxes provided that net radiation, air temperature, humidity, and wind velocity at screen height are available.