Piedmont National Wildlife Refuge

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Piedmont National Wildlife Refuge

• January 12, 2003
• 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 1018 acre prescribed burn
  conducted by the Piedmont National Wildlife
  Refuge. The burn was conducted on 12 January
  2003. The model simulations run from 1700 EST 12
  January through 0800 EST 13 January.

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Weather

• Weather during the burn was clear and dry but
  became progressively cloudy during the post-burn
  period. Cloud cover increased from scattered
  clouds to breaks in a cloud deck at about
  10-15,000 ft (3-5,000 m). A weak frontal trough
  extended across the area leaving burn site winds
  blowing mostly but weakly from the west. Then
  synoptic forcing became weak and at one time
  favored winds blowing from the north. Later in
  the night a high pressure regime built into the
  area from the west. The stronger synoptic
  pressure gradient acted to blow smoke up-valley
  and over a ridge to the east of the burn site.

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Modeling Information

• PB-Piedmont Version 3.0-2003
• Grid spacing 60m
• Domain size NA
• Visual domain NA
• Weather data Hourly METAR
• Elevation data USGS 30 m DEM

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The modeled location of smoke on the ground at
1800 EST about 15 minutes after sunset.
Drainage forcing is the reason for the threaded
patterns in the plume. Grid spacing is 60 m.
maximum elevation difference is about 150 m.
1800 EST 12 January 2003 PNWR
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During this period synoptic forcing favored winds
blowing lightly from the north. Synoptic forcing
coupled with drainage forcing to send most smoke
down valley.
2300 EST 12 January 2003 PNWR
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The next slide shows smoke at 0500 EST. Cloud
cover in PB-Piedmont causes weakening of drainage
forcing. Thus drainage forcing declined after
midnight just when synoptic forcing increased
with the approach of a high pressure system from
the west. The resultant effect was smoke blown
up-valley and over a ridge to the east of the
burn site. Smoke channeled up several side
valleys to the ridge. At 0450 EST, Fish
Wildlife Service personnel noted smoke all along
a road running along the ridge line. Click the
left mouse button to highlight in red where smoke
was observed.
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PB-Piedmont 3.0 PNWR 01/12/03 0500 EST
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Summary
The movement of smoke is a complex interaction
between synoptic forcing in sometimes rapidly
changing weather conditions and drainage forcing
which is modulated by terrain, relative humidity,
and cloud cover. Changing any of these factors
slightly can alter predicted smoke movement. In
this case, PB-Piedmont placed smoke over the
roadway on top of the ridge east of the burn site
at the location where smoke was observed.
PB-Piedmont also placed smoke over the roadway
running to the south of the burn area. There were
no reports of smoke along this road.