# Presentation: 714301

## Piedmont National Wildlife Refuge

- February 8, 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 367 acre prescribed burn conducted by the Piedmont National Wildlife Refuge. The burn was conducted on 8 February 2006. The model simulations run from 1800 EST 8 February through 0700 EST 9 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 mostly cloudy after 8:00 PM. Cloudy conditions weaken drainage flows. A low pressure center over South Carolina combined with a strong high pressure system to the west of the burn site to favor winds blowing from the west during the day of the 8th. The large scale forcing opposed west-flowing drainage winds. The below figure gives a measure of the strength of the forcing. The moderately strong forcing of 5-7 m/sec, in combination with cloudiness that weakened drainage flows, was sufficient to blow smoke up-valley. After 5:00 AM, forcing increased to 10-12 m/sec – favoring complete ventilation.

## Modeling Information

- PB-Piedmont Version 5.0-2006
- Grid spacing = 60m
- Domain size = 281x402 -> 16.9x24.1 km
- Visual domain = 8.0x6.4 km
- Weather data: Hourly METAR
- Elevation data: USGS 30 m DEM
- Elevation contour interval = 9 meters
- Elevation range is 96 – 206 meters

## The PB-Piedmont domain, roads, observation points for 8 February 2006. The yellow polygon encloses the burn site. 

- The PB-Piedmont domain, roads, observation points for 8 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 west at 3.1 m/sec beginning at 1800 EST. Note that this image is just the viewing domain. The time is 1900 EST, 55 minutes after sunset.

## Drainage forcing in PB-Piedmont at 2100 EST before the onset of cloudiness. Drainage winds carry smoke down-valley to near Point 12.

## The PB-Piedmont smoke plume at 0300 9 February 2006. Large scale forcing in combination with drainage wind – weakening cloudiness has reversed the flow to up-valley. Smoke has also been carried into side valleys east of Point 5. 

- The PB-Piedmont smoke plume at 0300 9 February 2006. Large scale forcing in combination with drainage wind – weakening cloudiness has reversed the flow to up-valley. Smoke has also been carried into side valleys east of Point 5.

## 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 9 February 2006

- 5: No smoke (0607)

- 6: No smoke (0609)

- 7: No smoke (0612)

- 8: No smoke (0615)

- 9: No Smoke (0622)

- 10: No smoke (0624)

- 11: No smoke (0631)

- Click left mouse button to view observation points.

- 12: No smoke (0640)

- 13: No smoke (0647)

- 14: No smoke (0652)

- 15: No smoke (0705)

## Summary:

- PB-Piedmont was correct at 9 of the 11 no-smoke observation points.
- Slight smoke on the burn unit was observed at points 6,7,9 and 10 but not at the location of the observation. PB-Piedmont placed scattered smoke around Point 6.
- 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 8.

## Smoke Matrix

- Smoke Prediction

- Yes                 No

- Smoke Observation

-   No                Yes

- 0

- 9

- 2

- 0