# Presentation: 717978

## Piedmont National Wildlife Refuge

- January 15, 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 391 acre prescribed burn conducted by the Piedmont National Wildlife Refuge. The burn was conducted on 15 January 2003. The model simulations run from 1600 EST 15 January through 0900 EST 16 January.

## Weather

- Weather during the burn and the post-burn smoke movement period was clear and dry. A high pressure system to the west of the burn site favored winds blowing from the northwest during the day of the 15th. The high moved over during the night setting up conditions for drainage forcing dominance. The very dry conditions favored rapid cooling and strong drainage forcing. The high passed to the east during the night setting up conditions favorable for brisk winds from the southeast by sunrise.

## Modeling Information

- PB-Piedmont Version 3.0-2003
- Grid spacing = 60m
- Domain size = 311x500 -> 18.6x30 km
- Visual domain = 12.6x18.9 km
- Weather data: Hourly METAR
- Elevation data: USGS 30 m DEM

## Modeling Information

- The next slide shows the PB-Piedmont viewing domain for the 15 January 2003 smoke simulation. The model burn area is shown by the blue square. The actual burn area is outlined by the white polygon. Smoke observations taken from 0800 –0954 by Fish & Wildlife Service personnel are located by numbers on the image and summarized by the list on the right hand side of the image.

## PB-Piedmont domain, roads, observation points 15 January 2003

- Blue square: model burn area
- 1,2,3,4: corners of actual burn area
- 5: light smoke
- 6: smoke
- 7: smoke
- 8: smoke boundary
- 9: smoke
- 10: smoke boundary
- 11: light smoke
- 12: smoke
- 13: smoke boundary - smoke south
- 14: smoke boundary
- 15: no smoke

## The modeled location of smoke on the ground assume smoldering is coming from everywhere within the model burn area. Initial winds are from the northwest at 3.3 m/sec beginning at 1600 EST. Note that this image is just the viewing domain. The actual model domain extends much farther (east) of what is shown here. The time is 1800 EST, approximately 15 minutes after sunset.

## A

- Drainage forcing in PB-Piedmont at 1900 EST breaks up the plume into smoke patches that are becoming trapped in three valleys (A, B, and C). The trapped smoke at C will play a major role in smoke location the next morning

- B

- C

## PB-Piedmont simulated smoke at 0200 EST 16 January 2003. The weather rapidly changed during the night as a high pressure center moved overhead. Synoptic forcing that favored winds from the northwest early in the period became tiny and variable as the high passed then favored winds blowing from the southeast by morning. At 0200 EST, drainage forcing was the dominant smoke mover. Smoke from A and B in the previous slide has merged to flow down the main stream valley toward observation point 13. Smoke from C in the previous slide has flowed into the main stream valley downstream from 13.

## 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 0800 EST 16 January 2003

- 5: Light smoke (0811)

- 6: Smoke (0820)

- 7: Smoke (0825)

- 8: Smoke boundary (0832)

- 9: Smoke (0837)

- 10: Smoke boundary (0856)

- 11: Light smoke (0904)

- 12: Smoke (0908)

- 13: Smoke boundary south (0920)

- 14: Smoke boundary (0954)

- 15: No smoke (0800)

- Click left mouse button to view observation points.

## Summary: Focuses on discrepancies between observations and model

- Summary: Focuses on discrepancies between observations and model

- Point 10: observation was smoke boundary; model placed no smoke nearby. Possible reason: northeastern edge of the burn area extended much closer to point 10 than did the model burn area.
- Point 13: observation had smoke running from 13 all the way to SR18. Model showed smoke only halfway.
- Point 15: observation of no smoke on Alison Lake. Model placed smoke in the area.

## Summary: What PB-Piedmont tells us

- Summary: What PB-Piedmont tells us

- Smoke movement at night bears little correlation with smoke movement during the day.
- It is not wise to predict smoke movement at night based on weather conditions during the day.
- Smoke carried along the ground some distance from the burn site during the day may become entrapped in different drainages and play an important role regarding where smoke shows up next morning.
- The combination of changing synoptic weather and drainage flows can move smoke in different directions.