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Accession Number:
ADA505962
Title:
Dynamically Resolved Simulation of Atmospheric Features and Turbulence Using Advanced Models and Adaptive Algorithms
Descriptive Note:
Final rept. 17 Jun 2004-30 Sep 2008
Corporate Author:
NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
Report Date:
2008-10-30
Pagination or Media Count:
36.0
Abstract:
In order to resolve atmospheric features, such as gravity waves to the degree necessary for accurate optical turbulence prediction, we developed an adaptive version of MM5 that incorporates the NCSU Dynamic Solution Adaptive Grid Algorithm DSAGA and a new four-equation hybrid LESRANS turbulence model that provides a new approach for the calculation of the index of refraction structure function Cn2, a quantitative measure of atmospheric optical turbulence. These four equations are used to model the turbulence kinetic energy , the variance of vorticity, the variance of potential temperature and its dissipation rate, respectively. The improvement in prediction of optical turbulence by the adaptive MM5 is documented by comparison with the models of Dewan and Jackson applied to unmodified MM5 output. By comparison with two sets of observations, the numerical results suggest that the adaptive MM5 Cn2 predictions approach binned observation variation in regions where the resolution has been improved by DSAGA, with little additional computational resources. However, predictions in both adaptive and fixed grid modes are degraded due to the fact that NWP codes, such as MM5, contain multiple types of numerical dissipation and in general use sponge layers at the upper boundary.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
