South Carolina Forestry Commission

1
South Carolina Forestry Commission

• March 7, 2006
• Smoke Simulation Analysis
• Gary L. Achtemeier
• USDA Forest Service
• Athens, GA

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Task Description

• The following set of slides summarize a
  PB-Piedmont post-burn analysis of smoke movement
  in the aftermath of a 400 acre prescribed burn
  conducted by the South Carolina Forestry
  Commission. The burn was conducted on 7 March
  2006. The model simulations run from 1600 EST 7
  March through 0800 EST 8 March. The site was
  located on the flat coastal plain of eastern
  South Carolina and thus provides a test of
  PB-Piedmont over land with little relief.

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Weather

• Weather during the burn and the post-burn smoke
  movement period was clear. Synoptic forcing was
  weak and ill-defined until about 0300 EST 8
  March. Initially, synoptic forcing favored winds
  blowing from the northwest away from where smoke
  was observed the next morning. After 0300 EST, a
  weak high pressure area formed along the SC-GA
  coast and favored light winds from the southwest.
  The geostrophic wind speed, a measure of the
  strength of the forcing by the large scale
  (synoptic) wind field ranged between 7.9 m/sec
  and 0.4 m/sec but was highly variable from hour
  to hour. The moderately strong forcing (gt5.0
  m/sec) would dominate drainage flows in the
  shallow basins of the coastal plain. Weak
  synoptic forcing (lt 2.0 m/sec) would still be
  sufficiently strong to oppose and possibly
  reverse southwest-flowing drainage flows in the
  coastal plain.

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Modeling Information

• PB-Piedmont Version 5.0-2006
• Grid spacing 60 m
• Domain size 302x340 -gt 18.1x20.4 km
• Visual domain 8.2x7.6
• Weather data Hourly METAR
• Elevation data USGS 30 m DEM
• Elevation contour interval 2 meters
• Elevation range is 0-35 meters

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The full 16.9x16.6 km model domain captures the
flat topographical relief of the coastal plain.
6
The PB-Piedmont viewing domain and observation
points for 7 March 2006. The white square
encloses the 400 acre burn site.
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The plume at 1700 EST, 7 March 2006 blows from
the northwest.
8
The plume at midnight (0000 EST 8 March 2006).
Synoptic forcing has shifted to favor winds
blowing from the southwest.
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Smoke Location EvaluationInterpreting 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

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PB-Piedmont analysis observations 0500 EST
1 No smoke (0500)
2 Light smoke SE of this point (0509)
3 Light smoke NW of this point (0513)
4 No smoke (0515)
Click left mouse button to view observation
points.
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PB-Piedmont analysis observations 0700 EST
5 Edge of smoke (0627)
6 Light smoke SE of this point (0654)
7 Light smoke NW of this point (0700)
8 No smoke (0706)
Click left mouse button to view observation
points.
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Summary

• At 0500 EST, PB-Piedmont correctly placed no
  smoke at 2 of 2 observation sites.
• At 0500 EST, PB-Piedmont correctly placed smoke
  between the two observation sites but not as
  widespread as was observed.
• At 0700 EST, PB-Piedmont correctly placed no
  smoke at 1 of 1 observation sites.
• At 0700 EST, PB-Piedmont correctly placed smoke
  near a single site next to the river.
• At 0700 EST, PB-Piedmont correctly placed smoke
  between the two observation sites but not as
  widespread as was observed.

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Smoke Matrix
Smoke Prediction
Yes No
0
3
No Yes
Smoke Observation
4
0