# Presentation: 842203

## Piedmont National Wildlife Refuge

- February 10, 2006
- Smoke Simulation Analysis
- Gary L. Achtemeier
- USDA Forest Service
- Athens, GA

## Task Description

- The following set of slides summarize a PB-Piedmont post-burn analysis of smoke movement in the aftermath of a 1314 acre prescribed burn conducted by the Piedmont National Wildlife Refuge. The burn was conducted on 10 February 2006. The model simulations run from 1600 EST 10 February through 0800 EST 11 February. Model smoke locations are compared with field observations collected by personnel from the Piedmont National Wildlife Refuge.

## Weather

- Weather during the burn and the post-burn smoke movement period was clear initially but became cloudy after 8:00 PM. A low pressure center developed over the Gulf of Mexico and moved rapidly to central Georgia by the end of the simulation period. Approximately 0.25 inches of rain fell. Winds shifted from the south to the east as the storm approached. The below figure gives a measure of the strength of the forcing. The strong forcing of 8-10 m/sec, in combination with cloudiness that weakened drainage flows, favored complete ventilation. From 1:00 AM forcing ranged from 10-16 m/sec then declined rapidly as the storm center approached shortly after 8:00 AM. The weak forcings (6.9  2.9 m/sec) allowed buildup of weak drainage flows.

## Modeling Information

- PB-Piedmont Version 5.0-2006
- Grid spacing = 60m
- Domain size = 296x350 -> 17.8x21.0 km
- Visual domain = 15.1x13.1 km
- Weather data: Hourly METAR
- Elevation data: USGS 30 m DEM
- Elevation contour interval = 10 meters
- Elevation range is 96 – 216 meters

## The PB-Piedmont domain, roads, observation points for 10 February 2006. The yellow polygon encloses the burn site. 

- The PB-Piedmont domain, roads, observation points for 10 February 2006. The yellow polygon encloses the burn site.

## The modeled location of smoke on the ground assume smoldering is coming from random locations within the model burn area. Initial winds are from the south at 4.1 m/sec beginning at 1800 EST. Note that this image is just the viewing domain. The time is 1800 EST, 9 minutes before sunset.

## The smoke plume at 0400 11 February 2006. Strong forcing from the northeast carries smoke to the southwest over the major drainages surrounding the burn site. 

- The smoke plume at 0400 11 February 2006. Strong forcing from the northeast carries smoke to the southwest over the major drainages surrounding the burn site.

## The PB-Piedmont smoke plume at 0600 11 February 2006. Weakening large scale forcing has allowed smoke to better organize into plumes flowing through drainages normal to the main north-south valley west of the burn site. Smoke is clearly seen in side valleys near Point 6. 

- The PB-Piedmont smoke plume at 0600 11 February 2006. Weakening large scale forcing has allowed smoke to better organize into plumes flowing through drainages normal to the main north-south valley west of the burn site. Smoke is clearly seen in side valleys near Point 6.

## Smoke Location Evaluation:Interpreting the Observations Shown in the Next Slide

- Red symbol means smoke observed
- Green symbol means smoke not observed
- Circle means model matched observation
- Triangle means model unsuccessful

## PB-Piedmont analysis & observations 0700 EST 11 February 2006. Red dots indicate where smoke and fog (RH=100%) may coexist.

- 6: No smoke (0627)

- 7: No smoke (0633)

- 8: Slight smoke (0637)

- 9: Slight smoke (0641)

- 5: No smoke (0619)

- 10: Slight smoke (0643)

- 11: No smoke (0646)

- Click left mouse button to view observation points.

- 12: No smoke (0652)

- 13: Slight smoke (0655)

- 14: Slight smoke (0657)

- 15: No smoke (0701)

- 17: Slight smoke (0709)

- 18: No smoke (0723)

- 16: No smoke (0705)

- 19: Slight smoke (0705)

## Summary:

- PB-Piedmont was correct at 9 of the 15 smoke/no-smoke observation points.
- About 0.25 inches of rain fell during the night. This may have decreased some smoldering. Only slight smoke was reported anywhere including at the boundaries of the burn site.
- PB-Piedmont assumes that all smoke is contained in the near-ground layer.  This was a case of ventilation for which strong winds and weak drainage winds would have favored rapid vertical mixing of the smoke. This in combination with little smoke observed on the burn site would explain the absence of smoke at Point 6.

## Smoke Matrix

- Smoke Prediction

- Yes                 No

- Smoke Observation

-   No                Yes

- 3

- 6

- 2

- 4