Applying CALMET surface energy balance equation computes the atmospheric diffusion stability to the influence of ISC simulation result
Date Issued
2008
Date
2008
Author(s)
Chang, Fu-Yi
Abstract
The atmospheric stability is one of important meteorological parameters in many air quality models, and the rationality of its decision method affects extremely the result of contaminants simulation. In the past the decision method of stability was often the Pasquill stability classification, for example ISC3 model. But it could only consider meteorological factor to the influence of stability, could not consider geographical factor. Therefore this research applies the theory of CALMET model. The stability is estimated with surface energy balance method during the daytime and Weil & Brower theory during the nighttime. The results show that the stability which is estimated with CALMET theory is more stable than the results of Pasquill method in ISC model. It was because that, CALMET considered surface parameters during the daytime. It could consider the evaporation which could depress the sensible heat flux. Because Pasquill could not consider the evaporation on surface, the unstable degree could be frequently overestimated. According to the results of three cases, the stability is unstable condition during most daytime; the stability is stable condition during the nighttime; the stability is neutral condition in day and night in turn time. And the main authority of the unstable degree is decided during the daytime and nighttime, it is the thermal turbulence and regards the sensible heat flux as the indicator during the daytime; it is the mechanical turbulence and regards the friction velocity as the indicator during the nighttime.
Subjects
Atmospheric stability
Surface energy balance equation
Bowen ratio
CALMET model
ISC3 model
SDGs
Type
thesis
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