An Estimation of the Bulk Transfer Coefficients for a Bare Soil Surface Using a Linear Model

Abstract

A linear heat budget model is developed to estimate the daytime means of the bulk transfer coefficients for heat and evaporation efficiency using the daily variation of observational data. The daily variation of shortwave radiation, ground-level air temperature, surface temperature, wind speed, and daily mean ground-level specific humidity are required to obtain the bulk coefficients. The relationship between the atmospheric resistance and the wind speed is also required. The daily variation of heat flux (1-h average) with respect to the surface heat budget can be reproduced using the same model and the presently estimated bulk coefficients within an error of 41 W m?2 for the sensible heat flux and within an error of 53 W m?2 for the latent heat. Sensitivity tests were performed under six different conditions. It was found that a systematic error of ±1°C in the surface temperature will lead to erroneous estimates of the bulk coefficients.