Verify the Bowen Ratio equation by using Eddy Covariance Method
Date Issued
2012
Date
2012
Author(s)
Li, Yi-Shian
Abstract
The air quality model to simulate pollutants’ diffusion is affected by the diffusion degree that determined by the atmospheric stability, and the calculation of the atmospheric stability can be obtained from sensible heat flux. Bowen ratio, the ratio between sensible heat flux and latent heat flux, and its rational decision will change the value of sensible heat flux as well as subsequently modify the result of contaminants simulation. Therefore, instead of setting Bowen ratio as a constant by recent air quality models, this research applies the theory of thermodynamics to deduce the estimated Bowen ratio formula that could find the time-varying Bowen ratio from time-varying weather information in Taiwan.
To verify the estimated formula, this research uses Eddy covariance data from Chilan and Guandu flux site in Taiwan to evaluate the feasibility of the formula by in-situ analysis method and then to propose one modified factorα. It is more consistent with real situation by such modified factor. According to the research result, the theoretical Bowen ratio is significantly underestimated at Chilan flux site but not at Guandu flux site. However, after applying factorα, both sensible and latent heat flux fit data that derived from Bowen ratio method. The atmospheric stability based on Eddy covariance is used to compare the resulting atmospheric stability with the theoretical, the modified and the constant Bowen ratio methods. The ratio of the same stability by the theoretical Bowen ratio and Eddy covariance is higher than the stability by the constant Bowen ratio, and the ratio that both the modified theoretical Bowen ratio and Eddy covariance show the consistent degree of the atmospheric stability is higher than 75%.
Subjects
atmospheric stability
bowen ratio
surface energy balance equation
sensible heat
eddy-covariance
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-101-R99541128-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):8bb802637a786ddf9ee1fce27e2c0a53