Monitoring the moisture status of the land surface in Sicily using an energy balance approach

In order to derive spatially resolved information on the water stress of vegetation, different data sources have to be combined. In general, remote sensing data provide a high spatial resolution, but few physical parameters, while point data from surface measurements show high accuracy, but are not spatially resolved. Thematic data like land use classifications give qualitative information of the surface cover, but remain static in time. In the present study, the moisture status of the land surface is monitored using the daily evolution of the evaporative fraction (EF). Among the various flux ratios used in energy balance modelling, EF has received special interest. EF is defined as the part of the available energy used for evapotranspiration. This quantity is an indicator of the moisture status of the land surface, mainly consisting of natural vegetation and agriculture. As a study region the island of Sicily has been chosen. Its Mediterranean climate is characterised by a dry and hot summer period and humid months in the winter season.