Radar measurements can suffer from lack of stability due to different causes: 1) Electronic fluctuations [Della-Bruna et al., 1997]; 2) General attenuation due to rainfall over the radome [Manz et al., 1999], which in attenuated radars could lead to a critical subdetection. It also may lead to improperly apply other usual correction procedures if signal stability is not controlled and corrected previously (as removal of screening effects from partial beam blocking, or rainfall attenuation). ASCMORE, an algorithm to monitor and control the stability of radar measurements and the attenuation by rainfall over the radome based on the analysis of the mountain returns technique [Delrieu et al., 1995, 1999] is proposed. It has been designed to work operationally on real time, and it is devoted to two objectives: 1) to give a real-time alert in case of significant signal instabilities; 2) to estimate a correction factor. The algorithm has been working operationally on the C-band radar of the Instituto Nacional de Meteorología located at Barcelona since January 2001. The analysis of several case studies have allowed us to propose an improved version of the initial one [Sempere Torres et al. 2001]. Selected case studies and results showing the importance of these problems in C-band radars and the need to deal with on real time are finally presented.

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