# Presentation: 715358

## Piedmont National Wildlife Refuge

- January 26, 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 374 acre prescribed burn conducted by the Piedmont National Wildlife Refuge. The burn was conducted on 26 January 2006. The model simulations run from 1700 EST 26 January through 0800 EST 27 January.

## Weather

- Weather during the burn and the post-burn smoke movement period was clear and dry. A high pressure system to the north of the burn site favored winds blowing from the northwest and north during the day of the 26th. The high moved to northeast of the site during the night and strengthened setting up conditions for strong northeasterly forcing. The geostrophic wind speed, a measure of the strength of the forcing by the nearby high pressure center increased from a weak 1.1 m/sec at 9:00 PM (favoring drainage wind formation) to moderately strong 10.5 m/sec by 1:00 AM (favoring ventilation). As the main ridge/valley system was oriented NE-SW, drainage flows were reinforced by the large scale forcing. Smoke in PB-Piedmont was quickly pushed down drainage but trapped in small NW-SE oriented side drainages.

## Modeling Information

- PB-Piedmont Version 5.0-2006
- Grid spacing = 60m
- Domain size = 337x364 -> 20.2x21.8 km
- Visual domain = 6.3x5.0 km
- Weather data: Hourly METAR
- Elevation data: USGS 30 m DEM
- Elevation contour interval = 8 meters
- Elevation range is 106 – 178 meters

## The PB-Piedmont domain, roads, observation points for 26 January 2006. The white polygon encloses the burn site. Note that observations are taken within or close to 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 north at 1.1 m/sec beginning at 1700 EST. Note that this image is just the viewing domain. The time is 1800 EST, five minutes after sunset.

## A

- Drainage forcing in PB-Piedmont at 1900 EST breaks up the plume into smoke patches that are becoming trapped in nearby drainages. Drainage flows have developed at A and B.

**A**

**B**

## A

- PB-Piedmont simulated smoke at 0200 EST 27 January 2006. The complex pattern shows smoke on higher ground being blown across drainages by strong large scale winds (A). Smoke at lower ground is more likely to be trapped and carried to the main drainage (dark green). Red dots identify where the relative humidity is 100 percent thus locating where smoke and fog might coexist. Some smoke is blown across the road into drainages (B).

**A**

**B**

**B**

## 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 observation points 0700 EST 27 January 2006

- 5: Dense smoke (0615)

- 6: Medium smoke (0618)

- 7: Smoke (0620)

- 8: Light smoke (0623)

- 9: Light Smoke (0625)

- 10: Light smoke (0631)

- 11: Light smoke (0641)

- Click left mouse button to view observation points.

## Summary:

- PB-Piedmont correctly placed smoke at all observation sites when smoke was observed.
- Smoke observations were taken within or just downwind from the burn site. This case could be judged as “easy” for PB-Piedmont since longer distance smoke movements were not observed.
- This case is the first run with the PB-Piedmont v5-2006 that contains the user-defined burn site polygon. In comparison with the original square representing the burn site, this option should give a more accurate representation of the initial source of smoke and thus a more accurate simulation of smoke location down wind.

## Smoke Matrix

- Smoke Prediction

- Yes                 No

- Smoke Observation

-   No                Yes

- 7

- 0

- 0

- 0