Re: Gaussian Plume Model

[Rich Oesterling <ogr@twinpeak.inel.gov>]

On Fri, 28 Oct 1994, LUIS BENEVIDES wrote:
 
> Greetings to who may read this! I have a question concerning the gaussian

Most people have *lots* of questions regarding the gaussian plume model:-)

> plume model. Does the effective height of the plume take into account the 

No - "effective height" is the physical height of the exhaust plus any 
vertical component due to bouyancy (can rarely be negative) or exhaust 
velocity.

> relative height of the receptor. In this I mean if there is rolling hills
> around the reactor, how does one take this into account. Please educate me!

Vertical structures, whether they are buildings, hills, or mountains, 
disrupt the air flow to varying degrees.  Typically there is a volume of 
compression on the windward side, and a volume of rarefaction on the 
leeward for any situation where the air flow is not completely laminar.  
Depending on the structure, there are also stagnation and recirculation 
volumes.

(True laminar flow in the atmosphere near a surface occurs only at low wind 
speeds across very smooth surfaces, such as a water body, when the 
conditions are isothermal.  Of course, laminar flow occurs, and is 
readily observed, within isothermal zones at altitude under highly stable 
conditions.)

In the case of rolling hills, the *ratio* of measured downwind concentration 
as a function of source release rate to the calculated value depends on 
all the usual variables: stability, wind speed, and release height, as 
well as slope, roundness, and dimensions of the hills.

For a discussion of these factors, go back to the source: _Meteorology 
and Atomic Energy_.  The problem is not trivial, if you want to treat it 
in more than just a cursory fashion.

Regards,

Rich Oesterling, CHP
ogr@inel.gov