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Simeonof Wilderness Area |
Site Name
IMPROVE:
SIME1 (Simeonof Wilderness)
Region
Alaska Maritime (Aleutian Islands)
Terrain
Terrain in the area is depicted in detailed 20 km terrain map and 2 km
terrain map.
The 25,855-acre Simeonof Wilderness consists of Simeonof Island in the
Aleutian Islands. It is ~ 93 km (58 mi) southeast of the Alaska mainland at
the western edge of the Gulf of Alaska. The region is subject to the Gulf of
Alaska maritime influence. Island elevations range from sea level to about
440 m (1,444 ft) at the central island summit.
The Simeonof IMPROVE monitoring site is SIME1, ~ 95 km northwest of the
Simeonof Wilderness Area. SIME1 is located at an elevation of 30 m (~ 100
ft) ~ 500 m east of the shoreline near the town of Sand Point town on
western Popof Island, ~ 17 km southeast from the Alaska Peninsula Wildlife
Refuge on the mainland. The terrain in the immediate vicinity of SIME1 is
flat, with higher hilly terrain comprising most of the island area east of
the site.
Representativeness
Aerosol data from SIME1 should be representative of aerosol concentrations
and composition in Simeonof Wilderness Area and in this region of the
Aleutians between the Bering Sea to the north and the Gulf of Alaska to the
south and east generally.
Nearby Population/Industrial Centers and Local Sources
There are no nearby major population centers or source regions. The town of
Sand Point Alaska is about 1 km southwest of SIME1, with no intervening
terrain features. Anchorage, the biggest city in Alaska, is ~ 900 km (~ 560
mi) northeast from SIME1. Volcanic emissions from the Aleutian Islands Chain
could influence the site during periods of volcanic activity. Ash plumes
from
Veniaminof Volcano 114 km (70 mi) northeast of SIME1 have been recorded
in recent years. Dust transport from Asia and forest burning on the Alaska
mainland may be the major factors influencing regional visibility. Aerosol
measurements may also show high sea salt/sulfate components. Fog is common.
Nearby Meteorological Network Data Stations
This map shows the location of the nearest air quality and meteorological
monitoring sites, with respect to the SIME1 IMPROVE site. The first order
Cold Bay Alaska NWS station with long-term
meteorological data is 140 km (~ 85 mi) west of SIME1. The nearest RAWS site
with a reasonable period of record is the
Booth Bay Alaska
RAWS site on Kodiak Island ~ 400 km (250 mi) northeast of SIME1 and
within the maritime influence of the Gulf of Alaska. It was established in
June 1995. The Cold Bay Alaska NWS station
is also the nearest upper air sounding site.
Wind Patterns
The Simeonof Wilderness and SIME 1 are within the global circulation zone of
midlatitude westerlies. Synoptic wind patterns of the region are modified by
the Pacific High Pressure Center in the summer and by the Aleutian Low in
the winter. At times, especially in the spring, the Pacific High over the
eastern Pacific Ocean intensifies and creates a ridge that diverts
midlatitude westerly flow from Asia northwards towards Alaska. This can
result in transport of Asian dust to the region. Towards the end of summer,
this ridge weakens and midlatitude flow becomes more zonal (westerly).
Monthly Cold Bay Alaska wind
roses are representative of wind patterns in this region of the Aleutian
Islands chain. Wind speeds are generally strong and wind directions
predominantly from the north to northwest, with southeast flow dominant in
the summer.
Inversions/Trapping
At times the marine boundary layer inversion may have potential for trapping
aerosols at low elevations locally, although there are no significant local
sources for particulate matter. Foggy days are common. Subsidence inversion
and stagnation and concurrent aerosol buildup could occur during periods of
persistent regional high pressure in the summer, and when southward spread
of polar air drops temperatures and is conducive to such conditions. This is
less likely to occur during winter periods when the Aleutian Low is
strongest.
Climatological Statistics
Cold Bay Alaska
Normals Means and Extremes are representative of the Aleutians in the
vicinity of SIME1. Other
Alaska Climate
Summaries are available from the
Western Regional Climate Center.
Meteorological Indicators
Keywords
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Last updated 22 September 2004
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