DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click HERE
to register or log in.
Potential Refractivity as a Similarity Variable
NAVAL OCEANOGRAPHIC AND ATMOSPHERIC RESEARCH LAB MONTEREY CA
Pagination or Media Count:
The validity of a common radiometeorological application of Monin-Obukhov M-0 similarity theory to potential refractivity Chi, which is a nonlinear combination of theta and q, is determined by whether the properly nondimensionalized chi gradient is a universal function of ZL. We develop expressions for the flux of chi and its scaling parameter, chi in terms of temperature and moisture fluxes, and an M-O similarity expression for the vertical chi gradient. Results show that even is theta and q are accepted as exactly following M-O similarity expressions, when the surface layer is stable, chi does not obey such an expression. That is, when properly nondimensionalized, the vertical gradient of chi does not collapse to a single universal function of ZL. The assumption that chi behaves as a similarity variable is approximately correct for well-mixed surface layers under unstable and near-neutral conditions. The gradient of chi is an important factor in determining microwave propagation conditions. We demonstrate the error induced in a simple algorithm when chi is assumed to obey M-O similarity theory. An alternative methodology, consistent with the application of similarity theory to theta and q, is then developed without requiring that chi itself satisfy similarity theory.
APPROVED FOR PUBLIC RELEASE