Intellectual Merits: The Principal Investigator (PI) will develop a new methodology for physical parameterizations in numerical models. The typical parameterization is a one dimensional model that estimates the physical entity being estimated (e.g. turbulent fluxes) using as input data from the larger scale model. The PI will bypass the one dimensional model approach by developing a unified parameterization that would be derived from a look up table (LUT) and based on input variables from the numerical model. For this research, the Principal Investigator will concentrate on subgrid scale diabatic heating. If this approach can be made sufficiently accurate, there would be a significant gain in computational speed for the model.
The PI will run the Regional Atmospheric Modeling System (RAMS) for selected months in 2006 over North America using the standard one-dimensional parameterizations for diabatic heating. The integrated diabatic heating rates will be stored and used along with the input variables and parameters to create a unified LUT that includes the sum of the effects from each original standard parameterization for the diabatic heating. RAMS, using the derived LUT to simulate the diabatic heating, will be integrated for the same time periods to determine if the resultant meteorological fields are reproduced with the same accuracy as in the original model run, but at a fraction of the computational cost. If the technique proves to be accurate, the PI will examine the variations in the simulated meteorological fields that result when perturbations are artificially imposed in the LUT in order to assess the sensitivity of the results to these variations.
Among the results of the research will be the size of the LUT that is needed to accurately capture the dimensionality of the output space, as determined by the ability of the regional model run with the unified LUT to recreate the original results when the traditional approach of using separate parameterizations for the different diabatic heating terms is used.
Broader Impacts: The research has broad impacts to the scientific community and to society. The replacement of existing parameterizations in weather and climate models with LUTs at a fraction of the cost of the original parameterization will provide a revolutionary improvement in model run speed. This research will directly contribute towards the education of one graduate student at the University of Colorado, Boulder.
