| RAMS MODEL | COMPUTING CLUSTER | MODELING IN PRINCE WILLIAM SOUND | AEFF HOME |
| COMPARISON WITH SAR DATA |
Mesoscale modeling with the Regional Atmospheric Modeling System (RAMS) - a central focus of the Alaska Experimental Forecast Facility |
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The model we use at the AEFF is RAMS, the Regional Atmospheric
Modeling System. RAMS,
which was developed at Colorado State University and MRC/
*ASTeR, is a multipurpose, numerical prediction model that simulates atmospheric
circulations ranging in scale from an entire hemisphere down to large
eddy simulations (LES) of the planetary boundary layer.
It is most frequently used to simulate atmospheric phenomena
on the mesoscale (horizontal scales from 2 km to 2000 km)
for applications ranging from operational weather forecasting to air
quality regulatory applications to support
of basic research
One of the strengths of RAMS is its versatility and applicability to a wide range of geophysical and hydrodynamic phenomena. RAMS has been successfully used with very high resolutions to simulate boundary layer eddies (10-100 m grid spacing), individual building simulation (1 m grid spacing) and direct wind tunnel simulation (1 cm grid spacing). RAMS and its predecessor codes were developed to perform research in modeling physiographically driven weather systems and simulating convective clouds, mesoscale convective systems, cirrus clouds, and precipitating weather systems in general. RAMS use has increased to more than 120 current RAMS installations in more than 30 different countries. |
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The version of RAMS used at the AEFF for large-scale simulations is
version 4.3 RAMS 4.3 provides a broad range of options and features ranging
from non-hydrostatic codes, resolution ranging from less
than a meter to a hundred kilometers, domains from a few kilometers to the
entire globe, and a suite of physical parameterizations.
This allows users to easily select appropriate options for
different spatial scales, meteorological problems or applications,
and locations.
Central to the versatility of RAMS is a multiple grid nesting scheme that permits solution of the primitive equations simultaneously on any number of interacting computational meshes of differing spatial resolution, using physics appropriate to the scale being consid- ered while maintaining physical and numerical consistency across all grids. The highest resolution meshes are used to model details of small-scale atmospheric systems. In our applications this includes such phenomena as flow over complex terrain, ographically-induced precipitation, atmosphere-ocean interactions and surface-induced thermal (katabatic) circulations. Coarse meshes are used to model the synoptic environ- ment of these smaller systems and provide boundary conditions for the fine mesh regions of interest. This multi-scale capability is very important in the Prince William Sound/ Cook Inlet region where the synoptic scale pressure gradients and associated weather systems interact strongly with local terrain. |