Soil Moisture: Microwave versus Infra-red based Estimates

Several different techniques for soil moisture estimation are available. Most of differences are strictly related to the application field. As a matter of fact hydrologists are more oriented to investigate MW-based methods, due to the importance of having measurements especially during flood occurencies, while agrometeorological applications generally have more mandatory requirements about the spatial resolution, so that IR-based techniques are preferred. Since the insitu measurements of soil moisture are precise but sparse and each value is only representative of a small area, the quantitative evaluation of the algorithms performance represents, as it often happens, a real challenge. On the other side, due to intrinsic methodological differences, the performance depend very much on the local soil composition and vegetation characteristics. This paper will discuss the above topic by comparing soil moisture measurements derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer (AMSR), instruments embarked on AQUA satellite, with ground validation measurements provided by the agrometeorological network in Friuli region situated in North Eastern Italy.