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Washakie Wilderness Area |
(Also see North Absaroka Wilderness Area,
Yellowstone National Park)
Site Name
IMPROVE:
NOAB1 (North Absaroka Wilderness Area)
Region
Central Rockies
Terrain
Terrain is shown in the 2 km terrain map and the 20 km terrain map.
The Washakie Wilderness Area consists of 704,529 acres around the headwaters
of the South Fork of the Shoshone River in northwestern Wyoming. It is
bordered on the west by the Teton Wilderness and Yellowstone National Park
and is across the North Fork of the Shoshone River from the North Absaroka
Wilderness Area to the north. Wilderness terrain is characterized by deep
narrow valleys and canyons separated by broad flat-topped mountains and
plateaus. Elevations range from ~ 2,000 m (6,000 ft) to 4,010 m (13,153 ft)
on Francs Peak on the eastern boundary. There are several peaks with
elevations of 3,660 m (12,000 ft) or higher.
The IMPROVE site representing the Washakie Wilderness and the North Absaroka
Wilderness to the north is NOAB1, located in Dead Indian Pass 40 km
northwest of Cody Wyoming and about 5 km northeast of the nearest North
Absaroka Wilderness Area boundary. NOAB1 is 40 km (25 mi) north of the
Washakie Wilderness boundary, with the upper Shoshone River North Fork and
mountainous terrain between. The NOAB1 monitoring site elevation is 2,480 m
(8,134 ft), 164 m lower than the summit of Dead Indian Hill to its northeast
and 20 m above Dead Indian Pass and nearby State Highway SR 296.
Representativeness
The NOAB1 IMPROVE site is in a well-exposed mountain pass location at a high
elevation that is near the 750 mb standard atmosphere pressure height. NOAB1
and the Washakie Wilderness are on the western fringe of the same air basin,
the Bighorn Basin. Aerosol data from NOAB1 should be representative of the
Washakie and North Absaroka Wilderness Areas and regional haze
characteristics in this region east of the Continental Divide generally. It
may at times be less representative of local features within the Wilderness
Areas such as canyon and valley locations isolated from upper air by winter
and nocturnal trapping inversions.
Nearby Population/Industrial Centers and Local Sources
The North Absaroka and Washakie Wilderness Areas are remote from any major
source regions. Salt Lake City is 500 km (300 mi) southwest of NOAB1 and
potentially upwind for prevailing wind directions. Nearby population centers
include Cody Wyoming 40 km southeast and Billings Montana, 150 km (100 mi)
northeast of NOAB1. The Naughton and Bridger Power Plants in southwestern
Wyoming, are ~ 300 km (200 mi) to the southwest and south, respectively.
Highest concentrations from local/regional sources may occur during regional
wildfire events.
Nearby Meteorological Network Monitoring Stations
Nearby meteorological monitoring network stations are shown in the data
network map and at the
US Climate Archive
and RAWS station US Climate
Archive sites. The
Rattlesnake
Mountain Wyoming RAWS site is at an elevation of 2,073 m (6,800 ft) on
the slopes of Rattlesnake Mountain 20 km (12 mi) southeast of NOAB1 and has
a period of record beginning in September, 1988. Its exposure may make it
reasonably representative of regional surface meteorology concurrent with
aerosol monitoring at NOAB1. The
Yellowstone National Park CASTNET site YEL408 is 80 km (50 mi) to the
west (see Yellowstone National Park Meteorological Description Page.)
Nearest first order NWS stations are at Billings Montana in the Yellowstone
River basin to the north and Lander Wyoming in the upper Wind River basin to
the south. Historical data for these and other regional first order NWS
stations are available via the
EPA Technology Transfer
Network website.
The closest upper air site is at Riverton Wyoming Montana (RIW). This and
other upper air sites are accessible via the
University of Wyoming Dept
of Atmospheric Science web page.
Wind and Transport Patterns
Regionally, wind patterns and transport flows are dominated by
westerly synoptic flows. During the winter, as the Pacific High weakens and
retreats southward, more easterly transport flows from the central U.S. and
Canada are common. Surface topographic features modify this pattern locally.
Monthly Lander Wyoming wind
roses are indicative of the pattern, with southwesterly flow predominant
at this surface station and an additional significant southeasterly
component in the winter. Note that these surface wind patterns may differ
from upper level winds because of local terrain effects. Aerosol transport
from distant source regions to the NOAB1 monitoring site will most often be
associated with upper level predominantly westerly synoptic flow. Locally,
NOAB1 may see daytime mesoscale upslope flow from the east associated with
mountain valley circulation in the adjacent upper Bighorn River basin.
Inversions/Trapping
NOAB1 is located in a mountain pass 500 to 600 m higher than the Yellowstone
River Clark Fork to the northwest and ~ 800 m above the floor of the wide
Bighorn River basin to the east and probably above most winter and nocturnal
surface inversions. In the summer regional subsidence inversions during
periods of high pressure and stagnation can result in widespread aerosol
buildup over periods of days. High summertime aerosol concentrations at
NOAB1 may result from regional sources such as western wildland fires in
conjunction with such episodes.
Climatological Statistics
Climate data derived from period of record measurements at the
Rattlesnake
Mountain Wyoming RAWS site should be typical of trends at NOAB1.
Lander Wyoming
Normals Means and Extremes are more representative of lower valley
bottom locations. Other
Wyoming Climate
Summaries are available from the
Western Regional Climate Center.
Meteorological Indicators for Local Sources
Keywords
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Last updated 16 December 2004
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