Measuring the Dynamic Soil Water Evaporation.

Soil water evaporation is a critical component of the soil surface water balance and the soil surface energy balance. In this study we measure the dynamic soil water evaporation with a heat pulse method. We measure the sensible soil heat fluxes and sensible heat storage with time and depth with heat pulse sensors, and calculate latent heat fluxes with time and depth based on a sensible heat balance. Results show that soil water evaporation occurs at the soil surface just following rainfall but the water evaporation front shifts gradually to subsurface soil after 2 to 3 days. The heat pulse measurements of dynamic and cumulative soil water evaporation are confirmed by Bowen ratio measurements, which independently measured the soil water evaporation during the same time period. We conclude that the heat pulse method is a reliable method in estimating dynamic soil water evaporation.