Piedmont National Wildlife Refuge February 14, 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 an 810 acre prescribed burn conducted by the Piedmont National Wildlife Refuge. The burn was conducted on 14 February The model simulations run from 1600 EST 14 February through 0700 EST 15 February. 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 variably cloudy. A high pressure center over south Georgia initially favored synoptic winds blowing from the west. By the end of the simulation period, the high, having moved east, in combination with an approaching low pressure area from the west, shifted the winds to blow from the southeast. The below figure gives a measure of the strength of the synoptic forcing. The strong forcing of m/sec, in combination with some cloudiness that weakened drainage flows, favored complete ventilation. Furthermore, the direction of the synoptic forcing (from the southeast) directly opposed drainage wind formation in NW-SE oriented valleys. Thus no significant drainage flow formation was observed on 14 February.

Modeling Information PB-Piedmont Version Grid spacing = 60m Domain size = 320x374 -> 19.2x22.4 km Visual domain = 10.0x8.8 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 14 February The yellow polygon encloses the 810 acre burn site.

The modeled location of smoke on the ground assume smoldering is coming from 25 random locations within the model burn area. Initial winds are from the southwest at 5.1 m/sec beginning at 1630 EST. Note that this image is just the viewing domain. The time is 1800 EST, 9 minutes before sunset.

The smoke plume at 0400 EST 15 February Strong forcing from the south blows smoke up-drainage to the north.

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 0700 EST 15 February : No smoke (0625) 7: No smoke (0632) 8: Smoke (0635) 9: Slight smoke (0637) 5: No smoke (0619) 10: Dense smoke (0639) 11: Light smoke (0643) Click left mouse button to view observation points. 12: Smoke (0653) 13: Dense smoke (0709) 14: Dense smoke (0728)

Summary: PB-Piedmont was correct at 10 of the 10 smoke/no-smoke observation points. Slide 6 (1800 EST) shows the plume drifting to the northeast at the end of the day. No smoke was modeled for any of the observation points at 1800 EST. This case gives another example of how weather conditions change during the night to shift winds and blow smoke in different directions.

Smoke Matrix Smoke Prediction Yes No Smoke Observation No Yes