Evaporation from a Wet Soil Surface Calculated from Radiometrically Determined Surface Temperatures

Abstract

The temperature of a naturally exposed, bare wet soil surface was measured with a narrow bandpass infrared radiation thermometer. Corrections were made for actual sky radiance and for surface emittance, the latter also determined in the field. When used to calculate evaporation rates with a Dalton-type equation containing a log-law wind function (drag coefficient × windspeed), excellent agreement was found with lysimeter values on both an hourly and daily basis. The results demonstrate the feasibility of surface temperature measurements and support the validity of the log law for describing transfer in the surface layer.