Accession Number : ADA291153
Title : Near Surface Dust. Late Time Atmospheric Effects.
Descriptive Note : Technical rept. 1 Sep 91-31 Oct 93,
Corporate Author : TITAN RESEARCH AND TECHNOLOGY DIV PRINCETON NJ A R A P GROUP
Personal Author(s) : Sykes, R. I. ; Henn, Douglas S. ; Cerasoll, Carmen P.
PDF Url : ADA291153
Report Date : 01 FEB 1995
Pagination or Media Count : 157
Abstract : Atmospheric processes determining the late-time evolution of near-surface dust concentrations from nuclear bursts are examined, with the objective of providing model representations for late-time dispersion codes. Turbulent transfer in the atmospheric boundary layer is an important phenomenon for small particles, since turbulent eddy velocities are on the order of 1ms-1 and extend from the surface up to altitudes of 1 km or higher. Simplified estimates for turbulence structure and diffusion rates are given. The effect of absorption of solar radiation by the dust is also considered, and a radiative transfer mode is described. Turbulent deposition of particles to various surface types, including open terrain or vegetative canopies, is considered and simple parameterization schemes are recommended. An extensive study of boundary layer flow over complex terrain has been conducted, using Large-Eddy Simulation to represent the energy-containing turbulent motions. A generalized scheme for estimating the average surface drag over complex terrain is derived. The effect of terrain on atmospheric turbulence levels and dispersion characteristics is studied, and simple estimation schemes for use in late-time models are suggested.
Descriptors : *RADIATIVE TRANSFER, *DUST CLOUDS, *NUCLEAR CLOUDS, NUCLEAR EXPLOSIONS, DISPERSING, BOUNDARY LAYER, TURBULENCE, EDDIES(FLUID MECHANICS), ATMOSPHERIC MOTION, PARTICLE SIZE, TERRAIN, ESTIMATES, CODING, DEPOSITION, DUST, PARTICLES, RADIATION ABSORPTION, DIFFUSION, SOLAR RADIATION, VEGETATION, ATMOSPHERE MODELS, EARTH ATMOSPHERE, ATMOSPHERIC PHYSICS.
Subject Categories : Atmospheric Physics
Distribution Statement : APPROVED FOR PUBLIC RELEASE