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North
Absaroka Wilderness Area |
(Also see Washakie Wilderness Area,
Yellowstone National Park)
Site Name
IMPROVE:
NOAB1
Region
Central Rockies
Terrain
Terrain is shown in the 2 km terrain map and the 20 km terrain map.
The 350,488-acre North Absaroka Wilderness Area is part of the Greater
Yellowstone Area of northwestern Wyoming, located along the northeastern
boundary of Yellowstone National Park, east of the Continental Divide.
Terrain is mountainous, dissected by numerous creeks. Elevations range from
~ 2,200 m (7,200 ft) to greater than 3,050 m (10,000 ft) on several summits.
The highest elevation is 3,724 m (12,216 ft) on Dead Indian Peak.
The IMPROVE site representing North Absaroka Wilderness and Washakie
Wilderness to the south is NOAB1, located in Dead Indian Pass 40 km
northwest of Cody Wyoming and about 5 km northeast of the nearest Wilderness
boundary. Site elevation is 2,480 m (8,134 ft), 164 m lower than the summit
of Dead Indian Hill to the 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. The
site has an unimpeded vista into the North Absaroka Wilderness. The North
Absaroka and Washakie Wilderness areas, and the NOAB1 monitoring site, 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 Wilderness Area is remote from any major source regions.
Salt Lake City is 500 km (300 mi) southwest 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 (Also, see Bridger
Wilderness Meteorological Description Page). 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 (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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