Copyright 2006 Accademia dei Georgofili
The estimation of precipitation. Precipitation is one of the geophysical parameters with higher variability in space and time at all scales, and it is key factor in many aspects of the Earth system dynamics and a basic data for a wide class of users. Research is undertaken in the last decades to investigate basic precipitation characteristics and to propose new instruments and techniques to estimate the rain amount at the ground. A critical step in developing any rainfall estimation technique is the establishment of a proper validation procedure, to provide the user a reliable description of the accuracy of the estimation. Different approaches are presented here, making use of different instruments and techniques: the use of disdrometers, polarimetric radar and multispectral space-borne sensors is discussed and few validation techniques are presented. Finally, a satellite-based rainfall estimation technique is discussed in the frame of the leaf wetness assessment problem: for one precipitating event occurred in Friuli on the 9 May 2004, radar and satellite data are processed in order to obtain precipitation maps by mean of a neural network scheme. The accuracy of such maps is assessed, evaluating the potential of the satellite point of view for its application outside the radar domain too.
