Precipitation Studies in Trade Wind Clouds - The Rain In Cumulus over the Ocean (RICO) Experiment

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This is a central project for the "Rain in Cumulus over the Ocean" (RICO) experiment, a multi-institutional collaborative project involving more than 15 institutions that plans to study trade-wind Cumulus clouds in Nov 2004 - Jan 2005. The studies will cover four key areas: * the processes that lead to rapid onset of precipitation in tropical cumulus clouds; * the transition from initiation to mature precipitating system in such clouds; * the effect of tradewind Cumuli on the properties of the tradewind layer; and * the role of precipitation in the energy balance in the tradewind regime.A focus of the study is an investigation of the rate at which rain forms in warm clouds, which appears to be faster than predicted by models or calculations. The investigators will investigate several hypotheses that have been advanced to explain this rapid onset of precipitation, including the roles of giant particles, turbulence, and entrainment. In the study, they will use recently developed observational capabilities, including new radar capabilities for detecting the nature of precipitation formation and new instruments for measuring the size distributions of cloud droplets and aerosol particles. The investigators also seek to study larger-scale characteristics and effects of tradewind Cumuli, eventually leading to improved understanding of the roles of these regions and of precipitation in the climate system.Broader impacts of this project include a strong educational component. This project and the broader RICO experiment will advance the training of graduate students and new investigators in this line of research through their involvement in the experiment and also through a special graduate-student seminar to be conducted in connection with the field experiment. This has also been the core effort around which the broader RICO experiment organized, and so has provided the nucleus for a concerted interactive effort involving many other investigators and institutions. The expected long-range impact will be that the effects of trade-wind Cumulus and of rain from warm clouds can be better represented in weather and climate models and so can lead to improved predictions of precipitation.