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Crater Lake National Park |
Site Name
IMPROVE:
CRLA1
Region
Cascade Range
Terrain
Terrain is shown in the
2 km terrain map and the
20 km terrain map.
The 160,290 acre Crater Lake National
Park is located in the Cascade Range in southwestern Oregon. Its
essential feature is the 10 km (6 mi) wide caldera that contains Crater
Lake. Lake elevation is 1,883 m. Rim elevations range from about 275 m to
570 m (900 to 1,873 ft) above lake level. The highest park elevation is
2,722 m (8,929 ft) at the peak of Mt. Scott, in the eastern Park area. The
National Park includes headwaters of the Rogue River that flows southwest
towards the Medford/Grants Pass area, and Sun Creek/Wood River that flows
southeast to the Klamath Falls area. The IMPROVE site representing
Crater Lake National Park is CLRA1,
just outside and to the south of the crater rim, elevation 1,963. It is
roughly 200 m lower than the rim elevation.
Representativeness
The CLRA1 IMPROVE site should be representative of aerosol characteristics
at Park locations during periods of uniform regional haze resulting from
regional forest fire events or transport from distant source regions.
Nearby Population/Industrial Centers and Local Sources
There are no nearby major source regions. The lower Willamette Valley of
western Oregon, from Portland to Eugene, is over 100 miles distant on the
opposite side of the Cascade crest. Central California valleys are more
distant, to the south. Nearest communities are Medford and Grants Pass, in
the Rogue River valley, where the major industry is timber.
Nearby Meteorological Data Stations
Nearby meteorological monitoring network stations are shown in the data
network map and at the
RAWS station US Climate Archive
site. The nearest site with representative hourly data that includes wind
data is the
Mount Stella Oregon RAWS site, located 12 km west of the Park
boundary at an exposed elevation of 1,438 m (4,715 ft).
Medford WSO AP
data is representative of regional climate at lower elevations. Upper air
data is also collected at the Medford RAOB station.
Wind and Transport Patterns
Synoptic winds in the region are generally northwesterly (from the
northwest), with an additional component of more southerly winds in the
winter with the weakening of the Pacific High Pressure System. This pattern
is indicated in monthly
Medford Oregon Wind Roses from Medford, in the Rogue River valley 50
miles southwest, elevation 1,330 m (4,362 ft), although there may be some
modification of surface wind directions due to local terrain effects There
may be some upvalley transport flow into the Park area via the upper Rogue
River valley, although the CRLA1 IMPROVE site is some 600 m (2,000 ft) higher
in elevation than the Rogue River valley floor near Medford and Grants Pass.
Potential local transport routes to the CRLA1 IMPROVE site include emissions
in the Rogue River valley transported directly via diurnal upslope/downslope
flow, mixed upwards with afternoon mixing, or trapped regionally under a
persistent subsidence inversion. Highest summertime measured concentrations
at CRLA1 are likely associated with regional forest fire events or transport
from distant source regions.
Inversions/Trapping
The inner crater is susceptible to surface based trapping inversions,
especially in the winter. Pollutant buildup within the rim would not affect
aerosol measurements at CRLA1, which is outside and downslope from the rim.
In the summer, the Rogue River valley nighttime boundary layer could be
mixed upwards to National Park elevations. Persistent summer inversions will
typically be larger scale subsidence inversions associated with stagnant
high pressure over the region, and can result in aerosol buildup over
periods of days. Subsidence inversion heights with typical elevations of
2,000 to 3,000 m (6,000 to 10,000 ft) could hold aerosol accumulations at
the CRLA1 site. Highest concentrations likely result when this warming and
drying condition leads to major forest fires in Southern Oregon and northern
California.
Climatological Statistics
Crater Lake
Climate data from Crater Lake National Park Headquarters gives long term
climate statistics for Crater Lake, excluding wind statistics.
Medford Oregon
Normals Means and Extremes are representative of lower elevations in the
Rogue River valley. Other
Oregon Climate
Summaries and
Northern California Climate Summaries are available from the
Western Regional Climate Center.
Keywords
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Last updated 9 December 2004
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