Precipitating clouds observed by 1.3-GHz boundary layer radars in equatorial Indonesia

Temporal variations of precipitating clouds in equatorial Indonesia have be en studied based on observations with 1357.5 MHz boundary layer radars at S erpong (6.4 degrees S, 106.7 degrees E) near Jakarta and Bukittinggi (0.2 d egrees S, 100.3 degrees E) in West Sumatera. We have classified precipitati ng clouds into four types: stratiform, mixed stratiform-convective, deep co nvective, and shallow convective clouds, using the Williams et al. (1995) m ethod. Diurnal variations of the occurrence of precipitating clouds at Serp ong and Bukittinggi have showed the same characteristics, namely, that the precipitating clouds primarily occur in the afternoon and the peak of the s tratiform cloud comes after the peak of the deep convective cloud. The time delay between the peaks of stratiform and deep convective clouds correspon ds to the life cycle of the mesoscale convective system. The precipitating clouds which occur in the early morning at Serpong are dominated by stratif orm cloud. Concerning seasonal variations of the precipitating clouds, we h ave found that the occurrence of the stratiform cloud is most frequent in t he rainy season, while the occurrence of the deep convective cloud is predo minant in the dry season.