Environmental Engineering Reference
In-Depth Information
1.18 An Updated Method for Estimating
of Surface-Layer Scaling Parameters from Routine
Ground-Based Meteorological Data
Marko Kaasik and Eva-Stina Kerner
Institute of Physics, University of Tartu, Estonia
Abstract
There is presented a method for rough estimation of Monin-Obukhov
length from meteorological measurements made routinely in ground-based stations.
The independent variables are wind velocity, cloud amount and solar elevation.
The method is based on bilateral relations of Pasquill stability classes with (1)
wind and insolation and with (2) surface roughness and Monin-Obukhov length on
the other hand. The result enables us to build up entire surface-layer scaling for a
local dispersion model. Resulting atmospheric stratification estimations are vali-
dated in a case study based on radiosounding profiles and mast data collected
during 3 years in Tallinn, Estonia.
1. Introduction
Although advanced numerical air quality models have far more realistic dynamics
and physics included and thus, are theoretically capable to predict the dispersion
of airborne ingredients with much higher precision and accuracy, the simple Gaussian
models are still widely in use for local and urban scale applications (Air4EU, 2005).
Due to lack of meteorological and emission data, the numerical models don't
perform significantly better, but consume much more computer resources. Often
the entire condition of surface layer must be still estimated from the surface-based
mean flow wind and other routine meteorological station data, as neither flux- nor
gradient-based micrometeorological measurements are available.
There is presented a technically new method for rough estimation of Monin-
Obukhov length and building up the surface-layer scaling for local air pollution
dispersion computations. Practical need for that method appeared due to pre-
processing of meteorological data series for a bi-Gaussian model AERMOD
(Cimorelli et al., 2005), version 6, for environmental impact assessment purposes.
