# Presentation: 842204

## Piedmont National Wildlife Refuge

- December 2, 2003
- 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 02 December 2003. The model simulations run from 1600 LST 02 December through 0700 LST 03 December.

## Weather

- Weather during the burn and the post-burn smoke movement period is an example of how rapidly changing weather conditions can impact post-burn nocturnal smoke movement. The weather was mostly clear and dry through the period. A weak low pressure trough maintained light and variable winds until shortly after midnight. Then an approaching and deepening low pressure system to the southwest coupled with a high pressure system to the northeast of the burn site to favor winds blowing from the northeast during the early morning of December 3. Geostrophic winds, a measure of the strength of the synoptic scale pressure field, increased from 3 m/sec to 12 m/sec during the period from midnight to 0700 LST. Thus weather conditions that favored drainage flow formation earlier in the period evolved into conditions that favored strong flow from the northeast and east later in the period.

## Modeling Information

- PB-Piedmont Version 3.0-2003
- Grid spacing = 60m
- Domain size = 272x448 ->16.3x26.9 km
- Visual domain = 16.3x17.8 km
- Weather data: Hourly METAR
- Elevation data: USGS 30 m DEM

- Smoke Behavior
- The points numbered 5-11 identify locations along roads (blue lines) where smoke was observed by PNWR personnel between 0600 – 0640 LST 03 December 2003. This case is interesting because smoke was observed along ridges. Thus PB-Piedmont is required to move smoke from the valleys to the ridges. The actual burn area is outlined by the orange polygon. PB-Piedmont uses the blue square. Streams of yellow dots at 1800LST – 36 minutes after sunset – show that drainage forcing is already constraining the flow through gaps in ridges.

- Smoke Behavior
- By 2000 LST, the remnants of the daytime plume are found between points 8 and 9 near the western edge of the map. Meanwhile, a strong drainage flow is transporting smoke down the Falling Creek valley between points 5 and 10.

- Smoke Behavior
- By midnight (0000 03 December 2003), drainage flows have carried smoke down the length of the the Falling Creek valley and into the Okmulgee River valley (wider green strip). Meanwhile, the approach of the strong low pressure system to the southwest has created a pressure gradient favoring winds from the northeast. Smoke has been pushed to the west side of the Falling Creek valley with some crossing the road through gaps in the ridge near Point 11.

## 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
- Light Smoke – smoke visible but no concern for drivers
- Moderate Smoke – smoke dense enough to slow traffic but not stop it

## Smoke observation points 0700 EST 03 December 2003

- 5: Light smoke (0605)

- 6: Moderate smoke (0607)

- 7: Light smoke (0610)

- 8: Moderate smoke (0620)

- 9: Light smoke (0630)

- 10: Light smoke (0635)

- 11: Light smoke (0640)

- Click left mouse button to view smoke observation points.

## Summary

- Drainage forcing dominated early in the period causing smoke transport from the burn site down the length of the Falling Creek valley. Then synoptic forcing that favored winds blowing from the northeast forced smoke up the west side of the valley and over the top of the ridge where it was observed at various sites along the road. Seven smoke observations were taken after 0600 LST on 03 December 2003. PB-Piedmont correctly placed the smoke at six of these observation sites.