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Flat Tops 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.
Flat Tops Wilderness is located in northwest Colorado. Terrain is composed
of a massive uplifted and eroded high plateau, level at upper surface
elevations, forming a region of flat-topped cliffs and mesas, with
occasional peaks. Elevations vary from ~2300 m (7600 ft) to the highest peak
elevation of 3,962 m (12,994 ft). Typical mesa top elevations are 3,400 to 3,500
m (11,000 to 11,500 ft). Terrain thus has similarities to both the Southern
Rocky Mountain and Colorado Plateau physiographic regions.
There is no IMPROVE site in the immediate vicinity of the Flat Tops
Wilderness. 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) and ~80
km (50 mi) south of the Wilderness, across the upper Colorado River valley.
Data Representativeness
The White River IMPROVE site WHRI1 is located in a more mountainous region,
separated from the Flat Tops by the Colorado River valley. It is at a
similar elevation as the high mesa tops in the Flat Tops, and may be
representative of regional layered haze at these elevations, which may at
times be above the regional haze layer. It is probably not representative of
lower Flat Tops elevations that could be more influenced locally.
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. There are no network data stations with wind data,
although there are several Snotel sites in the vicinity. The nearest RAWS
site is the Dead
Horse RAWS site, where data have been collected since 1985. This site is
just outside the Wilderness boundary to the northwest, at an elevation of
2,732 m (8,960 ft) and should be reasonably representative of surface
meteorology within the Wilderness boundary. Upper air structure is best
represented by upper air data from the Grand Junction NWS site, 120 km
west-northwest of the Wilderness Area.
Wind Patterns
Grand Junction long-term wind roses show predominantly southeasterly flow,
with additional northwesterly flow during winter. These wind roses may be
influenced by terrain channeling by the Colorado River valley near Grand
Junction, 125 km (80 mi) southwest of the Wilderness Area boundary. Wind
roses from the
Dead Horse RAWS site show a higher frequency of southwesterly
winds annually, especially with high wind speeds. At lower elevations within
the Wilderness Area wind patterns during light regional wind and stagnation
periods will show a pronounced diurnal pattern consistent with
mountain/valley upslope/downslope flow.
Transport pathways into the Flat Tops Wilderness Area are primarily via
upper level transport from distant source regions, especially source regions
west of the Continental Divide, consistent with regional haze. There may be
some low level transport into the area via the Colorado River drainage.
Inversions/Trapping
Lower elevations of the Wilderness Area may be 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). High elevations would typically be above trapped local haze
and may also be above regional haze trapped below large-scale subsidence
inversions during stagnation periods.
Climatological Statistics
Regional normals means and extremes are compiled for the
Grand Junction
NWS station. More locally representative long term climate data, from
1985 to the present is available for the
Dead Horse RAWS
site.
Meteorological Indicators for Local Sources
Keywords
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Page last updated 30 April 2004
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