| |
Mount Adams Wilderness Area |
(Also see Goat Rocks Wilderness Area)
Site Name
IMPROVE:
WHPA1 (White Pass)
Region
Northern Cascade Range
Terrain
Terrain is shown in the 2 km terrain map and the 20 km terrain map.
The Mount Adams Wilderness occupies 47,280 acres on the crest of the Cascade
Range, specifically the slopes of Mt Adams, an isolated volcanic cone in
southwestern Washington. Headwaters drainages on slopes of Mount Adams
within the Wilderness Area drain to the west to the Lewis River that flows
into the Columbia about 25 km (15 mi) north of Portland Oregon. Wilderness
elevations range from 3,757 m (12,326 ft) at the summit of Mount Adams to
about 1,000 m (3,280 ft) at the lowest Wilderness boundary on the southwest
slope.
The IMPROVE site representing Goat Rocks and Mt Adams Wilderness Areas is
WHPA1 located on the northern Goat Rocks Wilderness Area boundary at White
Pass Ski Resort near White Pass Washington, on the crest of the Cascade
range. The monitoring site elevation is 1,830 m (6,002 ft), corresponding to
a standard pressure height of 812 mb.
Representativeness
WHPA1 is at a well-exposed ridge crest location and should be very
representative of aerosol concentration and composition at similarly exposed
locations in the Mount Adams Wilderness. Its elevation and exposure should
also make it representative of regional characteristics and transport from
distant source regions at pressure heights near 850 mb that are relatively
unperturbed by terrain effects.
Nearby Population/Industrial Centers and Local Sources
The significant population centers and source regions nearest to the
WHPA1 IMPROVE site are Seattle and the Puget Sound area 100 (60 mi) to the
northwest and Portland Oregon 120 km (75 mi) to the southwest. The Centralia
power plant, which has implemented emission controls in recent years, is
located near Centralia Washington 100 km due west near the Cowlitz River
that has origins in the Goat Rocks Wilderness. Regional forest fires are
likely the cause of some of the highest aerosol concentrations seen at
WHPA1.
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. There are no stations with high time resolution (hourly) data near the
WHPA1 IMPROVE site, though there is a SNOTEL site nearby. The nearest RAWS
site, with hourly data including wind data is the
Hager Creek
Washington RAWS site elevation 1,098 m (3,600 ft), located on elevated
terrain overlooking the Cowlitz River valley just west of the western Goat
RocksWilderness boundary. Data from that site may be generally
representative of concurrent meteorology at the WHPA1 site. A CASTNET site,
MOR409 (Mount Rainier NP), is located in the Nisqually River Valley
downvalley from Mount Rainier National Park (see Mount Rainier NP
Meteorological Description Page).
Wind Patterns
Synoptic winds in the region are generally westerly. During the winter, with
high pressure over the Great Basin and Idaho and low pressure west of the
Cascades easterly gradient (synoptic) flow is common. The WHPA1 IMPROVE site
is located near the crest of the Cascades and should be well exposed to
these upper airflows and to aerosols transported aloft from upwind sources.
Lower Wilderness elevations may see more typical mountain/valley circulation
patterns, especially during periods of weak synoptic forcing, which bring
valley air to higher elevations during the day. At WHPA1, aerosols
transported with this mountain valley circulation would likely show a
diurnal pattern.
Inversions/Trapping
Because of WHPA1’s high elevation relative to surrounding terrain it should
be generally above surface based valley inversions in Wilderness Area
headwaters basins. Summertime subsidence inversions associated with the
establishment of the semi-permanent Pacific high-pressure system can result
in regional aerosol buildup over periods of days. Subsidence inversion
heights are typically at elevations of 2,000 to 3,000 m (6,000 to 10,000
ft), near the WHPA1 site elevation.
Climatological Statistics
Olympia
Washington Normals Means and Extremes are representative of low
elevation locations in western Washington source areas upwind of Goat Rocks
and Mount Adams Wilderness Areas.
Yakima
Washington Normals Means and Extremes are representative of climate
characteristics at low elevation locations east of the Wilderness Areas.
Other Washington
Climate Summaries are available from the
Western Regional Climate Center.
Keywords
|
Last updated 28 February 2005
|