Atmospheric Release Advisory Capability (ARAC)

File: 970606_aadem_02.txt
Page: 02
Total Pages: 15
Memo for Record									5 October 1990
Subject:   Atmospheric Release Advisory Capability (ARAC) 
               Calculations for USAF TAC/IN
1.   Due to the nature of the original request and the paucity of data regarding source terms
	we have made several assumptions. The purpose of this memo is to provide a record
	and clarification of those assumptions and the background reasoning from which they 
     	were derived. Additionally a description of the graphical plot format is provided to
     	assist in their interpretation.
2.   The attached calculations were made with the MATHEW/ADPIC suite of atmospheric 
	transport and diffusion models.   MATTHEW is a mass consistent wind field model 
	which provides the three-dimensional winds to the Atmospheric Diffusion Particle in
	      Cell (ADPIC) model.
3.   Since all of the six target sites provided to us are in flat terrain our model for these 
	calculations did not include any terrain ejects. The information that we received about
	the targets prompted us to consider two source descriptions and a grid that would be 
	generic to any of the targeted areas.   "Calc #1" is for a strike on one bunker or one
	building. Assuming weapons are laid down within five minutes, the resulting smoke
 	cloud from the deflagration will contain the onginal H.E. detonation cloud from the
 	first strike.  This assumption is based on a 2.5 meter per second (5 kt) surface-wind 
	and a top of the mixing layer wind of not more than 4.0 meters per second (8 kts) and
 	neutral stability conditions. The smoke source cloud immediately following 
	deflagration is assumed to be surface based with a 54 m (177 ft) horizontal radius and
 	a height of 493 m (1,617 ft). We have assumed a generic source material with a 
	normalized amount of 100 kilograms of toxins within the smoke cloud. We have 
	assumed a particle size distribution wide a median diameter of 1.0 micrometers and a
 	geometric standard deviation of 1.5 micrometers. It should be noted that this
 	assumption does not consider agglomeration of the source material within the smoke 
	cloud. If source amounts can be further refined the calculations can be scaled up or 
	down from the 100 kg generic source amount. We have described the material as 
	being genenc. We have assumed that any of the four source toxins that survive and are
 	in the smoke cloud will be in the size range noted above. Since we know very little 
	about the toxicity of these toxins we have calculated the integrated air concentrations
 	(units of mg-seconds/m3) and the surface deposition (units of mg-m2) of one generic
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