Differential Bare Field Drainage Properties From Airborne Microwave Observations

Time variations of the surface soil moisture can be monitored using active microwave remote sensing. With the existence of airborne systems, it is now possible to estimate this variable on a regional scale. Data from a helicopter‐borne scatterometer show that the surface water content reductions during a 9‐day period are quite different from one field to another. A simple model describing the water budget of the soil surface layer due to evaporation and drainage is applied. From this model, a pseudodiffusivity can be calculated for each field using only the remotely sensed data. This new parameter gives a quantitative estimate of the observed drying heterogeneities.