Modeling the Dispersion of Vapor and Aerosol Particulates in the Atmospheric Boundary Layer
Abstract
The turbulent flow in the atmosphere is so complex and ranges over such a large range of scales that even if we were able to describe its detailed structure it would be practically impossible to simulate it. The study of turbulent flow is therefore focused on describing the statistical characteristics of the turbulence. One makes the assumption that the turbulent flow can be separated into a slowly varying mean component and a rapidly varying turbulent component. To model the planetary boundary layer, one needs to average the processes over the grid volume and the time step. Averaging the equations of motions, humidity, heat and concentrations generates a number of second-order moments. Classical K-theory is the simplest way to deal with this "closure" problem. It is analogous to molecular diffusion and postulates the various moments, interpreted as fluxes, to be proportional to the local gradients of the corresponding mean fields. It is possible to write down formal balance equations for all the second order moments. These equations will then contain a number of new, unknown, third-order moments. Formal equations can be wriften for each of these, but this generates a still larger amount of unknown moments, fourth-order moments etc ad infinitum. All meso-scale models have to include information on the large-scale synoptic weather situation, either by using measured data from the studied area or by using data from a large-scale synoptic model. The lafter can be a global model, a regional model or in some cases, the mesoscale model itself. The last procedure is usually referred to as nesting of the mesoscale model in itself.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 28, 2000
- Accession Number
- ADA381846
Entities
People
- Darko Koračin
- Steven Chai
Organizations
- University of Nevada, Reno