Harold, your code has been such a help. Another question, have you considered a variable for mixing depth? Putting in the option of reflection off an elevated inversion layer? Cheers, Lisa
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06 Jan 2009
gaussianPlume
Gaussian Plume model of airborne particulate distribution
They don't give much room to describe the updates, and then hide them at the bottom. In any case, Lisa, you were right - almost all the temps should be in Kelvins so I converted them for calculations but left the input in Celsius for convenience. Thanks for pointing that out. I have since reviewed all the equations (with the exception of Carlson-Moses and CONCAWE plume rise) and confirmed unit analysis where possible (many equations had constants with unknown units). Later when I get more time I plan to try to verify with supplied datasets for the ISC3 Short-Term (ISC3ST) model.
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02 Jan 2009
gaussianPlume
Gaussian Plume model of airborne particulate distribution
Thanks Harold - that helped a lot.
One more thing, I may be wrong, but here -
case 'Briggs'
% Compute buoyancy and momentum factors
Fb=gc*vs*ds^2*(Ts-Ta)/(4*Ts);
Fm=vs^2*ds^2*Ta/(4*Ts);
Shouldn't temps be converted to Kelvin for the Briggs equations? From what I can gather input temps were in degrees C.
Cheers,
Lisa
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29 Dec 2008
gaussianPlume
Gaussian Plume model of airborne particulate distribution
Hi Lisa,
In general, you are asking to perform volume visualization. MATLAB provides several options for what you are asking - if you search "Volume visualization" in MATLAB help you will find an extensive resource detailing how to do it. The 'C' variable that is returned is similar to the "scalar" volume data used in the examples given where C is a 3 dimensional matrix with a value for concentration at each point. In general, what you are attempting to do is difficult on a computer screen as the outside colors will obscure the interior data points. Methods around this limitation include transparency or taking "slices" from the volume. Again, the standard MATLAB help includes many functions that will help you to do this. Good luck.
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29 Dec 2008
gaussianPlume
Gaussian Plume model of airborne particulate distribution
Hi Sam Duris. This code was originally submitted as a homework assignment, and I regret if any errors have slipped in. Alas, I do not have a "standard text" available that display the proper results for the sigma_z curves, and would appreciate if you could point out where on the Internet I might be able to obtain for comparison/validation. Further, if you would be so kind as to list the specific problems/errors you encountered, I will be happy to try to address them. I have since located the two errors you point out where I inadvertently mixed km and m in computing sigma_z for rural and sigma_y for urban. I have also updated the documentation to note that most of the equations were actually taken from the ISC3 User's Manual, Vol II. It should be noted that this software is rather outdated, the EPA preferring AEROMOD/CALPUFF instead. Also, many of these models can be downloaded for free I think as well. I should note that many of these options have not been tested by me for accuracy. The division by zero errors likely come from passing 0 as a distance for evaluation and this will likely generate errors for which there is no real good solution other than having the user avoid calculations at 0 distance. The "documentation errors" to which you refer are too vague for me to locate - please clarify. Thanks for bringing up these errors and I look forward to improving this code.
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