Determining Sensible Heat Fluxes At and Beneath a Soil Surface.

Sensible heat balance theory has been applied for measuring soil evaporation with heat-pulse sensors. Experimental evidence and numerical analysis, however, have indicated that the measurements of soil sensible heat fluxes are subject to errors at the topmost soil layer. The objective of this study is to develop and test a procedure to provide accurate determination of sensible heat fluxes in the 0-3 mm soil layer. Soil surface temperature is measured with an infrared sensor, near surface soil temperatures are recorded at millimeter scale with thermocouples, and the corresponding soil water contents are determined gravimetrically. These data, along with the pre-established soil thermal property and water content functions, are used to calculate the sensible heat fluxes at and just beneath the soil surface. The new procedure will be illustrated using field measurements on a sandy loam soil.