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Cabinet Mountains Wilderness Area |
Site Name
IMPROVE: CABI1
Region
Central Rockies
Terrain
Terrain is shown in the 2 km terrain
map and
the 20 km terrain map.
The Cabinet Mountains Wilderness Area occupies 94,272 acres along the higher
reaches of the northern Cabinet Range in northwestern Montana. It
essentially consists of slopes leading down from a narrow line of peaks that
runs north to south for ~ 65 km (40 mi). Terrain is rugged craggy peaks and
valleys. Elevations range from around 1,200 m (3,900 ft) along the
surrounding Wilderness boundary to 2,664 m (8,738 ft) at the summit of
Snowshoe Peak. Several peaks along the crest are near 2,450 m (8,000 ft) and
higher.
The IMPROVE site representing the Cabinet Mountains Wilderness Area is
CABI1, 5 km outside of the southernmost extent of the Wilderness. The site
is at a well-exposed location on the crest of a ridge leading down from
Green Mountain to the east. Site elevation is 1,434 m (4,704 ft), well above
Noxon Reservoir and the Clark Fork River valley immediately to the west,
with a bottom elevation near 730 m (2,400 ft).
Representativeness
The CABI1 IMPROVE site is well exposed and should be very representative of
regional aerosol characteristics.
Nearby Population/Industrial Centers and Local Sources
This western Montana Wilderness Area is remote from any major source
regions. The nearest major population center is Spokane Washington, 140 km
(~90 mi) straightline west-southwest from CABI1 and upwind for prevailing
westerly winds. Missoula Montana is ~ 180 km (~110 mi) southeast and
upstream from CABI1 via the Clark Fork River. Nearby emission sources may be
associated with timber and mining operations.
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. Nearby monitoring sites with hourly data include the
Libby Montana
RAWS site and
Cabinet (Trout
Creek) Montana RAWS site although these sites are at low elevations
relative to the CABI1 site and have short periods of record beginning in
2001. Long term data from Spokane or Kalispell may be marginally
representative of concurrent meteorological conditions at CABI1. Historical
data for these and other first order NWS stations are available via the
EPA Technology Transfer
Network website.
The closest and most representative upper air site is at Spokane Washington
(OTX). Data for 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, with frequent easterly flows in the winter. Monthly
Missoula Montana wind
roses indicate this pattern, with northwesterly flow predominant at this
surface station and a significant east-southeasterly component in the
winter. Note that these surface wind patterns may differ somewhat from upper
level winds because of terrain effects. The CABI1 site is at a relatively
high ridge crest location, but may still be affected by channeled
mountain/valley flow in the Clark Fork River valley. Down-valley flow
through this major valley would be from the direction of the Missoula area,
~ 160 to 180 km (100 to 110 mi) upstream to the southeast.
Inversions/Trapping
The Clark Fork River valley near the CABI1 site may be subject to surface
based inversions especially in the winter, although the CABI1 elevation some
700 m (2,300 ft) above the valley floor may keep it above valley inversions
much of the time. In the summer regional subsidence inversions during
periods of high pressure and stagnation can result in regional aerosol
buildup over periods of days. High regional aerosol concentrations may occur
during summertime stagnation and subsidence inversion periods in conjunction
with western wildland fires.
Climatological Statistics
Missoula Montana
Normals Means and Extremes are representative of similar elevation
locations in western Montana. Other
Idaho Climate
Summaries and
Montana Climate Summaries are available from the
Western Regional Climate Center.
Meteorological Indicators for Local Sources
Keywords
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