Simulate the Mixing Layer Height of Taiwan by CALMET Model
Date Issued
2005
Date
2005
Author(s)
Hsu, Rong-jing
DOI
zh-TW
Abstract
Mixing layer height(MH) is very important for that the air pollutants in the atmosphere can be transferred vertically and diluted. As MH develops much higher, the signification deterioration episodes happen much fewer. That is the reason the air pollution science focus the MH in the environment discussions.
As so far, the MH can be judged by the upper air vertical temperature structure and measured surface temperature. The MH is set on where the surface temperature decreasing on the adiabatic lapse rate along the altitude meets the upper air temperature. Unfortunately the method often makes the mistake as MH as the unstable surface temperature and not very well for the lapse of upper air temperature slope. It should take more consideration for the MH development. Generally the mechanisms of MH development are different. For the daytime MH, heat buoyant turbulence production determines the vertical extent of dispersion because of on unstable situation, on the contrary, in the stable MH at nighttime, the mechanism is mechanical turbulence.
In this study, the CALMET model with the characteristic MH simulations of above mechanisms is used to simulate Taiwan MHs in 2003. In order to confirm results of simulations, they are compared with the MH calculated by real measured data including MTP5 and observations project of MH in south Taiwan.
From the result of the study, the daytime overland MH is influenced by overland sensible heat flux, in the other side, nighttime overland MH and oversea MH get the friction wind speed to judge. But when daytime overland MH get more cloud above, MH gets developed slowly. If the same cloud above somewhere on the same moment, the higher Bowen Ratio of the section gets higher MH and speeds MH development.
Subjects
可感熱通量
鮑溫率
Mixing layer height
CALMET
Sensible heat flux
Bowen ratio
Type
thesis
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