___________________________________________________ _____________________ B-1 

### Appendix B

Development of Stack Parameters and Vertical Distri butions for Modeling Large

Wildfires in the CCOS Domain.

C. Loomis Alpine Geophysics August 4, 2003

This document describes the methodology used for ve rtical distribution of emissions estimates for the wildfires occurring during the CC OS modeling episodes. During the CCOS modeling episode of July 29 – August 3, 2000 t wo large wildfires occurred in the modeling domain: the July 23-31, 2000 Plaskett fir e in Monterey County, and the July 22-August 8, 2000 Manter fire in Tulare County. Da ily emissions estimates and related parameters were calculated and provided by ARB for inclusion into the emissions modeling. (Scott K., 2003a, 2003b) These data were then utilized to develop a plume profile, using the techniques outlined in a recent report of the Fire Emissions Joint Forum (FEFJ) of the Western Regional Air Partnership (WRA P) (Air Sciences, 2002). The hourly emissions were assigned based on the followi ng standard profile (all values are taken directly from the FEFJ report):

Hour 1 2 3 4 5 6 7 8 9 10 11 12

% 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 2.0 4. 0 7.0

Hour 13 14 15 16 17 18 19 20 21 22 23 24

% 10.0 13.0 16.0 17.0 12.0 7.0 4.0 0.53 0.53 0.53 0.5 3 0.53

For each hour of the episode, the wildfire virtual acreage was calculated using the fuel loading factors provided by ARB, and the virtual ac reage sizes were used to determine to
the size classes of the fires. The size classes wh ere then used to determine the parameters required to calculate the plume characteristics:

Class 1 2 3 4 5 Size (virtual acres) 0-10 >=10-100 >=100-1000 >=1000-5000 >=5000

BE (size) 0.4 0.6 0.75 0.85 0.9 Ptop Max (m) 160 2400 6400 7200 8000 Pbot Min (m) 0 300 800 1600 1600

These values, along with the buoyancy efficiency as a function of the hour of the day, were used to calculate the bottom of the plume, the top of the plume, and the proportion of the emissions fumigated into the first layer, fo r each grid cell in the fire area, and for each hour of the episode.

To model the vertical distribution of the plumes, a series of stack parameters were constructed for each grid cell, and each hour of th e episode. The portion of the emissions attributed to the plume, rather than the fumigation layer, was distributed to each of the___________________________________________________ _____________________ B-2 stack release points, with the fumigation portion g oing directly to the first layer (zero plume rise). The stack points were inserted into t he emissions model at 25, 75 and 100 meters, and then at every 100 meters up to the top of the plume. Emissions were evenly allocated to each release point, beginning in the l ayer corresponding to the bottom of the plume, and continuing to the top of the plume.

References

Air Sciences, Inc. 2002. 1996 Fire Emissions Inven tory. Draft Final Report. Lakewood,
CO. On-line link: http:/www.wrapair.org/forums/FEJF1/emissions/FEJF19 96EIReport_021208.pdf

Scott, K. 2003a. Emissions estimates for the July- August 2000 Manter Fire. Technical Memoradum, ARB-PTSD

Scott, K. 2003b. Emissions estimates for the July 23-31 2000 Plaskett2 Fire. Technical Memoradum, ARB-PTSD