# Presentation: 888597

## Piedmont National Wildlife Refuge

- 03 March 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 750 acre prescribed burn conducted by the Piedmont National Wildlife Refuge. This burn was conducted on 3 March 2006. The model simulations run from 1700 EST 2 March through 0700 EST 4 March. 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. A high pressure system west of Georgia approached during the night to become centered over the state. Winds blew from the northwest throughout the period but diminished as the center of the high approached. The below figure gives a measure of the strength of the large scale (synoptic) forcing during the analysis period. Forcing of 17.8 m/sec was sufficient for ventilation. Forcing declined to 2.7 m/sec by 0700 EST. This favored strong drainage flow formation. Thus, as the analysis that follows shows, a well-ventilated plume gradually responds to local wind effects with drainage flows predominating by morning.

## Modeling Information

- PB-Piedmont Version 5.0-2006
- Grid spacing = 60m
- Domain size = 294x404 -> 17.6x24.2 km
- Visual domain = 11.4x10.1 km
- Weather data: Hourly METAR
- Elevation data: USGS 30 m DEM
- Elevation contour interval = 10 meters
- Elevation range is 88 – 208 meters

## The PB-Piedmont domain, roads, observation points for 3 March 2006. The yellow polygon encloses the burn site. 

- The PB-Piedmont domain, roads, observation points for 3 March 2006. The yellow polygon encloses the burn site.

## The modeled location of smoke on the ground assumes smoldering is coming from random locations within the model burn areas. Initial winds are from the west at 5.5 m/sec beginning at 1700 EST. Note that this image is just the viewing domain. The time is 1800 EST, 28 minutes before sunset.

## The smoke plume at 2000 3 March 2006. The plume has broken into strips and patches of smoke that are concentrated in the valleys located downwind from the burn site yet are still ventilating to the southeast. A drainage flow strengthened by synoptic forcing in the NW-SE oriented valley pushes smoke rapidly past Point 15

## The PB-Piedmont smoke plume at 0000 EST 4 March 2006. Drainage flows into the NW-SE oriented valley have strengthened. Ventilation still casts a large field of particles southeast of the burn site to the bottom and corner of the grid. 

- The PB-Piedmont smoke plume at 0000 EST 4 March 2006. Drainage flows into the NW-SE oriented valley have strengthened. Ventilation still casts a large field of particles southeast of the burn site to the bottom and corner of the grid.

## The PB-Piedmont smoke plume at 0600 LST 4 March 2006. Scattered patches of smoke remain over areas that were ventilated earlier. Most smoke is contained in drainage flows south of the burn site. Red dots show where fog and smoke  may coexist. Note the lack of smoke along the road near Point 14 yet smoke is still trapped on nearby slopes. 

- The PB-Piedmont smoke plume at 0600 LST 4 March 2006. Scattered patches of smoke remain over areas that were ventilated earlier. Most smoke is contained in drainage flows south of the burn site. Red dots show where fog and smoke  may coexist. Note the lack of smoke along the road near Point 14 yet smoke is still trapped on nearby slopes.

## 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 0600 EST (0700 analysis was lost)

- 5: No smoke (0605)

- 6: No smoke (0606)

- 7: No smoke (0608)

- 8: Smoke (0610)

- 9: Thick smoke (0614)

- 10: Slight smoke (0617)

- Click left mouse button to view observation points.

- 11: Slight smoke (0620)

- 12: Slight smoke (0624)

- 13: No smoke (0628)

- 14: Slight smoke (0637)

- 16: No smoke (0643)

- 17: Smoke (0654)

- 15: No smoke (0640)

- 18: Smoke (0656)

- 19: Smoke (0700)

- 20: Slight smoke (0703)

- 21: No smoke (0711)

- 22: Slight smoke (0713)

- 23: No smoke (0716)

## Summary:

- PB-Piedmont was correct at 14 of the 18 smoke/no-smoke observation points.
- This was a case of initial strong ventilation driven by synoptic scale forcing. Synoptic forcing weakened to allow drainage forcing to dominate late.
- Model forecasts of no smoke where slight smoke was observed (Points 12 & 14) could be explained by very thin residues of smoke hanging in the woods after ventilation ceased. PB-Piedmont tends to concentrate particles in valleys.
- Observations of no smoke where the model predicted smoke (Points 15 & 16) are harder to explain. The main drainage leading from the burn site was reinforced by synoptic forcing. The road follows a small ridge and it might be possible that there was no smoke at Point 15 while smoke was located in the basin just off the road.
- Point 16 was at the bridge. Note from Slide 9 that the road was visible and the main concentration of particles was just west of the road. This suggests that a drainage flow running down the valley from Point 12 to Point 16 may have pushed the smoke to the west of Point 16. The model retains some smoke surrounding Point 16, however, and thus the model is given an error.

## Smoke Matrix

- Smoke Prediction

- Yes                 No

- Smoke Observation

-   No                Yes

- 8

- 6

- 2

- 2