Accession Number : ADA132362

Title :   A Vertical Wind Angle Standard Deviation Calculation Method for the Unstable Surface Boundary Layer.

Descriptive Note : Research rept.,


Personal Author(s) : Biltoft,Christopher

Full Text :

Report Date : Aug 1983

Pagination or Media Count : 23

Abstract : This report is an introduction to basic similarity theory arguments and the application of the theory to practical problems in diffusion. It is intended to assist individuals with only a passing acquaintance with diffusion theory in the planning and execution of diffusion and hazard studies. A fundamental diffusion problem is the dilution that results from turbulent vertical cloud growth. Vertical cloud growth is described by the standard deviation of the vertical distribution of cloud material (sigma z). Estimates of sigma z are frequently obtained from Pasquill-Turner (P-T) stability categories. Sigma z can also be calculated as the product of travel distance (x) and the standard deviation of the vertical wind angle (sigma e). An explicit functional relationship between sigma e and the stability parameter z/L, where z is height and L is the characteristic length, is derived from similarity theory. This functional relationship is verified on a set of precisely measured micrometeorological field data. The performance of similarity theory sigma e calculations and P-T estimates is subsequently tested using sigma e data collected at DPG. The similarity theory computations are shown to be substantially superior to the P-T sigma e estimates. Adoption of similarity theory arguments should materially improve Army testing and hazard prediction efforts involving atmospheric diffusion and transport processes.

Descriptors :   *Wind shear , Turbulence , Cloud physics , Meteorological data , Diffusion , Temperature gradients , Wind , Standard deviation , Stability , Boundary layer

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE