Laboratory and field measurements of raindrop oscillations

This study presents new measurements of raindrop oscillations in laboratory and field conditions. A 2-D video disdrometer is used to detect the shape of oscillating raindrops. The studies that were conducted to examine the os cillatory behavior of drops reveal that there is a lack of observations of the large drop oscillations (Andsager et al. 1999). Yet, these drops have s ignificant importance on radar rain estimation. Therefore, the new laborato ry study is particularly designed to expand our knowledge on oscillatory be havior of large raindrops. The preliminary laboratory tests indicate that t he drops are less oblate than the equilibrium shapes. Regarding the field s tudies, a large sample of raindrops was collected in several tropical field campaigns. The raindrops are mostly distorted and canted due to the enviro nmental wind. An algorithm that determines the drop orientation and canting angle is added to the current system. This would reveal one of the most co mprehensive data set on the oscillating behavior of raindrops in natural ra in. The role of the oscillating raindrops on polarimetric parameters and su bsequent rain estimation will be added to the discussion. (C) 2000 Elsevier Science Ltd. All rights reserved.