Force Restore Technique for Ground Surface Temperature and Moisture Content in a Dry Desert System

The level of the surface temperature as well as surface moisture content is important for the turbulent transports of sensible and latent heat, respectively, but this level is also crucial for the survival of shrubs, plants, insects, and small animals in a desert environment. To estimate the surface conditions, the force-restore technique for surface temperature as well as surface moisture has been applied under extreme dry desert condition. A simple physical model was constructed in which the force-restore technique for surface moisture has been included. This model simulates the accumulated dew amounts as well as the early morning drying process. A measurement program carried out in the northwestern Negev desert of Israel (Nizzana) gathered data on daily surface temperature, daily dew deposition amounts, and micrometeorological conditions during the dew formation and drying process. Actual dew amounts were assessed using microlysimeters. Model simulations agreed well with the observations. It appeared also that the reduction of the vapor pressure in the soil's pores under extremely dry soil conditions is essential for the dew process.