Combined use of radar and satellite information for precipitation estimation in Hungary

Radar and satellite measurements can be used for the detailed description of the properties of precipitating clouds. Radars primarily detect the existing raindrops. From the satellite radiances, however, one can derive such additional physical characteristics of the cloudiness that can provide information on the further development of the precipitation systems. In this study the authors used digitized data from a 3 and 10 cm MRL-5 radar and satellite data from the Advanced Very High Resolution Radiometer (AVHRR) on board the polar orbiting NOAA satellites. From the AVHRR radiances they derived cloud-top temperature, optical thickness and effective cloud droplet size. They also determined a cloud-class flag using thresholding and clustering classification techniques. The radar and satellite images were transformed into the same geographic projection format and displayed simultaneously for qualitative evaluation. In addition, an empirical relationship was established between coincident ground precipitation measurements, radar data and satellite cloud parameters using data from a two-year period over Hungary