This paper presents a range of applications of the Regional Atmospheric Modeling System (RAMS), a comprehensive mesoscale meterological modeling system. Applications discussed in this paper include large eddy simulations (LES) and simulations of thunderstorms, cumulus fields, mesoscale convective systems, mid-latitude cirrus clouds, winter storms, mechanically- and thermally-forced mesoscale systems, and mesoscale atmospheric disperision. A summary of current RAMS options is also presented. Improvements to RAMS currently underway include refinements to the cloud radiation, cloud microphysics, cumulus, and surface soil/vegetative parameterization schemes, the parallelization of the code, development of a more versatile visualization capability, and research into meso-α-scale cumulus parameterization.

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A comprehensive meteorological modeling system?RAMS

Mesoscale fluxes over heterogeneous flat landscapes for use in larger scale models

We have developed a framework to parameterize mesoscale fluxes of heat, moisture, and momentum, in a cloud-free environment, which result from heterogeneous heating of flat land surfaces. The importance and parameterizability of these mesoscale fluxes is demonstrated using the mathematical concept of predictability. This methodology is used to estimate the relative importance of mesoscale, as contrasted with turbulent fluxes, in the Konza Prairie of Kansas during the FIFE field experiment. 0 1997 Elsevier Science B.V.

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Mesoscale fluxes over heterogeneous flat landscapes larger scale models for use in

We evaluate the mesoscale vertical velocity induced by stress changes in the surface layer as a function of the size of the rough patch in relation to environmental parameters. The nature of the flow per- turbation strongly depends on the relation between the width of the rough patch and the two natural scales of the flow, i.e. the inverse inertia wave number and the inverse of the Scorer parameter. When the width of the rough patch is comparable to the inverse inertia wave number or larger, the atmospheric perturbation is trapped, the vertical scale equals the depth of the stress surface layer, and the horizontal scale equals the Ross- by radius. When the width of the rough patch is larger than the inverse of the Scorer parameter, but smaller than the inverse inertia wave number, the atmospheric perturbation is a hydrostatic gravity wave with a verti- cal wave number equal to the Scorer parameter. When the width of the rough patch is comparable to the inverse of the Scorer parameter, the atmospheric per- turbation is a propagating lee wave with a vertical wave number equal to the Scorer parameter. When the ambient flow is strong over a small rough patch, the flow is irrotational. The same limitations, inherent to the linear gravity waves excited by the forcing in the atmosphere (e.g. mountain waves, gravity waves ini- tiated by convection, etc.), apply to the mesoscale per- turbation induced by a rough patch.

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J. T. Lee

Papers

Mesoscale Vertical Velocities Generated by Stress Changes in the Boundary Layer: Linear Theory