Weather radar anaprop conditions at a Mediterranean coastal site

Many weather radars are affected by some type of anomalous propagation (AP) with a wide variety of frequency and intensity. Some geographical areas ha ve been described to be particularly prone to AP, Even in some sites, AP is not statistically abnormal at all but dominant. Severe AP cases have been reported in coastal areas affected by strong temperature inversions and hum idity contrasts such as the Baltic Sea, the Indic Ocean or the Mediterranea n. In this paper we present average and extreme propagation conditions in t he coastal area of Barcelona (NE Spain) calculated using three years of rad iosonde data. Occurrence of different propagation conditions is discussed a nd related to local prevailing circulations such as the sea breeze with par ticular interest in the nearby Vallirana weather radar. The effect of some extreme ducting episodes seems to be remarkable in beam blocking correction procedures leading to wrong precipitation estimates when anaprop and rainf all occur at the same time. The use of radiosonde and mesoscale NWP data to derive operationally propagation conditions jointly with other existing te chniques based in the analysis of radar data is overviewed. (C) 2000 Elsevi er Science Ltd. All rights reserved.