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RICO:We helped devise this NSF sponsored field program to evaluate how shallow cumulus, characteristic of the trades, precipitate and the role precipitation plays in determining the aggregate behavior of fields of such clouds. The program was centered around the use of active remote sensing, such as the S-Band Polarization Radar (SPol) developed and maintained by the National Center for Atmospheric Research. During RICO, SPol was based on Barbuda (left) flight operations and shipboard remote sensing were used during RICO to augment SPol's view of this climatologically critical cloud regime. |
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Center for Multiscale Modeling of Atmospheric Processes (CMMAP): Work on the low-cloud theme continues work started as part of the Climate Process Team which seeks to improve the representation of low clouds, and cloud susceptibility in climate models. Disparities in the representation of low cloud fields is one of the leading causes of uncertainty in predictions of climate change from increases in Greenhouse gases. Our work has focused on the development of cloud resolving models for the use in multiscale modeling approaches, the improvment of traditional parameterizations, and the development of novel analysis techniques, for instance through the study of cloud feedbacks in aqua-planets. |
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Physics Grid: Here we explore novel strategies for coupling atmospherics and physics in large-scale numerical models. The physics grid is based on the idea of an independent discretization for atmospheric physics and dynamics, thereby allowing physical grid columns to be super or subcolumns. Such a grid is envisioned to help promote veritical resolution studies and HMM (heirarchical multiscale method) using large-eddy simulation at the microscale solver, and is shown in the schematic on the left. |
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DYCOMS-II was an NSF sponsored field program devised specifically to measure entrainment rates in marine stratocumulus, an image of which (courtesy of G. Vali) is shown on the left. In addition to definitive entrainment rate estimates, this program helped quantify the rate at which stratocumulus precipitate, and discovered curious clearings (termed pockets of open cells, or POCS) associated with precipitating regions of the flow. Download an overview of DYCOMS-II here. |
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GEWEX Cloud Systems Studies (GCSS): Much of our work in centered around and inspired by the GCSS boundary layer working group which strives to use simulation (in our case, large eddy simulation) to understand and better represent boundary layer cloud regimes in climate models. On the left we show the evolution of cloud top and base from data collected during RF01 of DYCOMS-II and as represented by an ensemble of 18 large-eddy simulations. A description of this case study can be found here. Current work with a student (Verica Savic-Jovcic) investigating the dynamics of precipitating stratocumulus is linked to here. |
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DNS and level sets for Clouds. This project is part of the Metström Schwerpunkt Program of the DFG, with researchers at the Frei Universität in Berlin (hence Knut's picture on the left) and Aachen. Here we try to use novel numerical strategies to both better understand and represent mixing processes at cloud top interfaces (such as shown in the DYCOMS-II image above). This work, like much of that discussed above is ultimately oriented toward unraveling the role of clouds in climate, the later of course being an issue for which Knut is metaphor. |