Cloud and precipitation studies using millimeter-wavelength radars

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Clouds play a critical role in Earth's climate through the reflection, absorption and emission of radiation, the vertical transport of heat and moisture, and the generation of precipitation and its associated latent heat release and evaporation. Despite ever increasing computational power and model sophistication, the poor representation of cloud processes continues to be one of the major sources of uncertainty in numerical simulations of climate and weather. In order to adequately understand the role of clouds and improve their parameterization in numerical models, fundamental (process) studies on all scales important to cloud formation, evolution and dissipation are required. Observational data sets are a crucial element of such studies because many cloud processes, such as precipitation formation, cloud turbulence, entrainment, and ice crystal evolution, remain insufficiently understood mechanistically. The proposed research builds upon the PI's expertise on the analysis of millimeter-wavelength radar observations and the introduction of novel retrieval algorithms of microphysical and dynamical properties in clouds and precipitation. Using cloud radars as a keyhole in cloud-scale processes and in synergy with other optical or microwave sensors, we propose to work on three main research areas: characterization of the vertical velocity field in ice clouds and its relationship to large-scale meteorology and precipitation initiation in warm clouds The proposed analysis will use state-of-the-art observations and process models to produce novel information on these two issues of crucial importance to model cloud parameterization. This information will provide better understanding of the cloud-scale processes involved in rain initiation, entrainment, and cirrus formation, and this understanding will improve our ability to better parameterize those processes in large-scale models.