William Cotton

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This paper is the second in a series of articles describing the new microphysics scheme in the Regional Atmospheric Modeling System (RAMS). In this part, a new two-moment microphysical parameterization is described. The proposed scheme predicts the mixing ratio and number concentration of rain, pristine ice crystals, snow, aggregates, graupel and hail. The(More)
The impact of giant and ultragiant cloud condensation nuclei (.5-mm radius) on drizzle formation in stratocumuli is investigated within a number of modeling frameworks. These include a simple box model of collection, a trajectory ensemble model (comprising an ensemble of Lagrangian parcel models), a 2D eddy-resolving model, and a 3D large-eddy simulation(More)
The microphysics module of the version of the Regional Atmospheric Modeling System (RAMS) maintained at Colorado State University has undergone a series of improvements, including the addition of a large-clouddroplet mode from 40 to 80 mm in diameter and the prognostic number concentration of cloud droplets through activation of cloud condensation nuclei(More)
Ž . Ž . Two-dimensional simulations of transition fall and spring season Arctic stratus clouds ASC were conducted using a sophisticated cloud resolving model with bin microphysics coupled to a two-stream radiative transfer model. The impacts of temperature variation and various ice microphysical processes on the evolution of the simulated mixed-phase ASC(More)
Toward the end of the Cirrus Regional Study of Tropical Anvils and Cirrus Layer–Florida Area Cirrus Experiment (CRYSTAL–FACE) field campaign held during July 2002, high concentrations of Saharan dust, which can serve as cloud condensation nuclei (CCN), giant CCN (GCCN), and ice-forming nuclei (IFN) were observed over the peninsula of Florida. To investigate(More)
In this paper we review observational and modeling studies of cloud venting by a wide variety of cloud types ranging from ordinary cumuli, to ordinary cumulonimbi, mesoscale convective systems and tropical and extratropical cyclones. We have used explicit cloud-resolving simulations with RAMS to illustrate the nature of the process of venting of boundary(More)
A three dimensional model for simulating the effect of enhanced cloud condensation nucleus (CCN) concentrations on stratocumulus clouds is presented. The model is a largeeddy simulation version of the Regional Atmospheric Modeling System (RAMS) with explicit representation of the CCN spectrum and cloud droplet spectrum. Results of two dimensional tests of(More)
The hypothesis that inertial instability plays a role in the upscale development of mesoscale convective systems (MCSs) is explored by sampling environments that supported the growth of MCSs in the Preliminary Regional Experiment for STORM (Stormscale Operational and Research Meteorology) (PRE-STORM) network with high quality special soundings. Secondary(More)