Evaluation of the Cloud Particle Imager and Investigations of Ice Multiplication

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This project is centered on an evaluation of the performance characteristics of a new instrument called the CPI (cloud particle imager) and application of the instrument to airborne studies of ice crystals in clouds. Based on advanced optical design and complex image processing, the CPI detects and produces high-resolution images of cloud particles down to a size of several micrometers, far exceeding the capabilities of previous instruments. For quantitative cloud physics studies, the CPI must be able not only to detect and form images of ice crystals, but also measure their concentration in space. This measurement requires an understanding of the sensitivity and response of the instrument, and the dependence of the observed signals on adjustable system parameters such as the intensity of the laser beam, the minimum acceptable particle size, and the particle detection threshold. Accordingly, the first objective of the program is to carry out theoretical calculations, laboratory studies, and airborne measurements designed to evaluate the performance characteristics of the CPI. This work will be done in collaboration with researchers from the National Center for Atmospheric Research. The second objective is to employ the CPI in studies of cloud regions having high concentrations of ice crystals. These studies bear on the question of ice crystal multiplication and will be conducted in collaboration with Dr. Alan Blyth of the New Mexico Institute of Mining and Technology. The program is expected to lead to a thorough understanding of the capabilities and limitations of the CPI, new algorithms for processing CPI data, and data on ice crystals in convective clouds that will enable the testing of different theories of ice crystal multiplication.