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Arches National Park |
Site Name
IMPROVE: ARCH1 (data from 3/2/88 through 5/1/92)
Region
Colorado Plateau
Terrain
Terrain is shown in the 2 km terrain
map and the
20 km terrain map.
Arches National Park
terrain comprises the 2 to 4 km wide Salt Valley Wash in the north and the
narrower Courthouse Wash in the south, both of which drain to the Colorado
River to the south and southeast. The Colorado River, elevation about 1,210 m
(3,970 ft) at this point, is the southern boundary of the Park. Highest
elevations of 1,600 to 1,700 m (5,250 to 5,580 ft), 400 to 500 m higher than
River elevations, are along the ridges bounding the Salt Valley Wash on the
north side, in the northernmost Park reaches. Terrain is generally eroded
and complex.
The IMPROVE site, ARCH1, is located near the ridge forming the northeastern
boundary of Salt Valley Wash. Data collection at ARCH1 started 3/2/98 and
ended 5/1/92.
Representativeness
Aerosol data collected at ARCH1 should be representative of vistas
overlooking the Park.
It should represent aerosol composition and concentration at lower
elevations near the Colorado River when the atmosphere is uniformly mixed.
Nearby Data Stations
The nearest monitoring site with detailed meteorology including wind and
humidity is the NWS Moab Canyonland Field office, which began monitoring in
summer of 2003. Other nearby monitoring network stations are shown in the
data network and at the
US Climate Archive
and RAWS station US Climate
Archive sites. The nearest surface station with long-term data is the
Arches NP
Headquarters COOP site, with long-term temperature and precipitation
data.
The nearest upper site with measurements representative of upper air
structure at Arches NP is Grand Junction, Colorado RAOB site.
Wind Patterns
Annual and seasonal wind roses from the Canyonlands NP CASTNET site (CAN407)
should be reasonably representative of wind direction frequencies at Arches
NP ARCH1 site. These wind roses show predominantly east-southeasterly flow,
especially in the summer, with higher frequencies of west-northwesterly flow
in the other seasons, especially winter. There is probably a diurnal
upslope/downslope pattern at bottom elevations in the Salt Valley and
Courthouse washes, with nighttime drainage toward the Colorado River.
Potential transport routes into Arches NP include low-level transport into
the area via the Colorado River drainage, and upper air transport via upward
mixing in distant source regions and advection aloft into Park areas.
Inversions/Trapping
Surface based radiation inversions may occur, especially during the fall and
winter, in which case the ARCH1 site may be above the inversion cap if the
inversion depth is less than about 400 m (1,300 ft). The more likely
inversion condition is regional scale subsidence inversions that form over
the Colorado Plateau during periods of stagnant high surface pressure. This
situation is most likely to occur during the extended summer, May - October,
when pressure and temperature gradients in the region are weakest, and wind
circulations therefore weaker.
Climatological Statistics
Arches NP climate (temperature, precipitation) is typified by data from the
Arches NP
Headquarters COO site. Regional normals means and extremes are compiled
for the Grand
Junction NWS station
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