Cloud Condensation Nuclei (CCN) and Large Nuclei in Rain In Cumulus over the Ocean (RICO)

Nevada System Of Higher Education, Desert Research Institute, Reno NV

Investigators

Abstract

The goals of this project are to measure cloud condensation nuclei (CCN) in air ingested into trade wind Cumulus clouds and use those measurements to consider how the CCN population influences the development of rain in those clouds. New features of the instrumentation will allow the measurements to extend to low supersaturation (large particle size), an important extension because such particles are thought to be important in warm-rain initiation. The measurements will also be made by different instruments providing different growth times for the droplets that form on the CCN to investigate if the limited growth time available in the instrument biases the measurements. The investigators will also study the possible role of occasional Saharan-dust episodes in accelerating rain formation. The project is part of the "Rain in Cumulus over the Ocean" (RICO) experiment, a multi-investigator study of warm rain formation and the nature of trade wind Cumulus clouds. The CCN measurements are a critical component of the broader experiment because, as the key input determining the initial droplet size distribution, they are needed by many of the other investigators in their studies of specific hypotheses regarding the warm-rain process. Other broad impacts of the project include likely resolution of an instrumentation controversy affecting many other microphysical studies, better understanding of rain formation as it influences weather and climate, and graduate student training in this area of research.