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Eagles Nest Wilderness Area |
Site Name
Nearest IMPROVE site is the White River National Forest site, WHRI1, near
Aspen.
Region
Southern Rocky Mountains
Terrain
Terrain is shown in the 2 km terrain
map and
the 20 km terrain
map.
The Eagles Nest Wilderness is located in north-central Colorado, west of the
Continental Divide. Terrain is composed of high peaks, escarpments, and
narrow mountain valleys. Elevations range from 2,394 m (7,850 ft) to 4,126 m
(13,534 ft), with 17 peaks over 3,960 m (13,000 ft).
The nearest IMPROVE site is the White River National Forest site, WHRI1,
located near Aspen at an elevation of 3,418 m (11,211 ft). WHRI1 is ~ 80 km
(50 mi) southwest of the Wilderness Area boundary.
Data Representativeness
The White River National Forest site, WHRI1, is at a high elevation and
should be representative regionally of aerosol composition and concentration
at similar elevations in Eagles Nest Wilderness Area although it is
separated form the Wilderness Area by ~ 80 km (50 mi). It will probably not
be representative of lower elevations in the Wilderness, which may
frequently be isolated within lower level terrain-induced radiation
inversions.
Nearby Population/Industrial Centers and Local Sources
Nearby Data Stations
Nearby monitoring network stations are shown in the data network
map and at
the US Climate Archive
and RAWS station US Climate
Archive sites. The most representative meteorological data site with
wind data is the
Dowd Junction RAWS site where data collection began in July, 1985. This
site is on a bluff above the Colorado River canyon- I70 corridor, elevation
2,743 m (8,998 ft) and may show some terrain effect on wind directions, but
the exposure is fairly representative. The nearest long-term upper air
station is at Denver/Stapleton, on the plains at the foot of the Rockies.
Either this station, or Grand Junction, have regionally representative upper
air data although both sites are in terrain that is significantly different
from terrain in the Eagles Nest Wilderness.
Wind Patterns
Wind roses from the
Dowd Junction
RAWS site show seasonal and annual wind patterns at a site above the
upper Colorado River channel. Annually, wind directions are east-west, with
a slightly more westerly component, especially for high wind speeds. In the
summer there are slightly more easterly winds, which include an easterly
nighttime drainage component. The predominant wind direction, representative
of regional transport winds, is from the west. This should also be true of
higher exposed locations within the Wilderness. At lower valley elevations,
wind patterns will be typical of mountain/valley upslope/downslope winds,
especially during regional low wind and stagnation episodes.
Transport pathways into the Eagles Nest Wilderness Area are primarily via
upper level transport from distant source regions, especially to the west
being west of the Divide. Locally, transport from local sources such as
wildland fires will be upslope/downslope within the valleys and basins.
Inversions/Trapping
The deep canyons and basins of the Wilderness Area are subject to frequent
diurnal radiation temperature inversions that could trap aerosols locally,
especially during wildland fire episodes. Regional stagnation and subsidence
inversions could occur, especially during summer months. From May to
October, long term records show an average of nearly one air stagnation
event per month during this period in western Colorado, where a stagnation
event is defined as stagnation conditions that persist for 4 days or longer
(Wang and Angell,
1999).
Higher elevations are probably above trapped local haze and may also be
above regional haze trapped below large-scale subsidence inversions and
surface-based radiation inversions.
Climatological Statistics
Regional normals means and extremes are compiled for the
Grand Junction
NWS station. Climate data representative of Eagles Nest Wilderness Area
are also collected at the
Dowd Junction
RAWS site.
Meteorological Indicators for Local Sources
Keywords
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Page last updated 30 April 2004
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