Site Name
IMPROVE:
REDW1
Region
Klamath Mountains
Terrain
Terrain is shown in the 2 km terrain
map and the 20 km terrain
map.
Redwood National Park consists of
27,792 acres of coast and coastal mountains in northern California. The
several unconnected sections of the Park include 37 miles of coastline
between the Oregon border and McKinleyville, California. Elevations range
from sea level to about 1,000 m (3,000 ft). As part of the coast ranges that
present the first obstruction to moist air from the Pacific, it has a high
annual average precipitation, though not as high as coastal rainforests
farther north in Washington, Canada, and Alaska. Total annual precipitation
on the northern California coast is about 305 cm (120 in), mostly during the
winter when the Aleutian Low is at its most southerly position over the
eastern Pacific. Precipitation varies considerably with inland distance and
with elevation. The furthest inland extent of the National Park is about 25
km (15 mi) from the coast. Besides the coast and mountains, the most
significant topographic features are Smith and Klamath Rivers that empty
into the Pacific in the northern and southern National Park areas,
respectively.
The IMPROVE site representing the Redwood National Park is REDW1, located at
a more or less central location with respect to the Park sections though not
actually within Park boundaries. It is near the mouth of the Klamath River
at an elevation of 245 m (804 m) as shown in the 20 km terrain map.
Representativeness
The REDW1 IMPROVE site is centrally located with respect to Park locations
at a midrange elevation and should be quite representative of aerosol
concentration and composition within the National Park. There may be some
modest influence by airflow down the Klamath River, which may be a transport
route for emissions from the interior such as wildfire emissions that could
influence measurements at the monitoring site locally.
Nearby Population/Industrial Centers and Local Sources
The nearest population center is the Crescent City area near the mouth of
the Smith River and the northern boundary of the National Park, population
about 4,000.
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 network sites within the National Park boundary. The
Klamath COOP
site is located near the IMPROVE site and may be representative of
meteorological conditions at the IMPROVE site, although it does not include
wind data. Wind data is collected at the
Schoolhouse
California RAWS site located in the southern National Park area at an
exposed location about 25 km (15 mi) from the coast. Data from this site may
be regionally representative with respect to wind patterns, although it may
not be as representative of conditions at the REDW1 IMPROVE site since it is
farther inland and at a higher elevation of 805 m (2,640 ft). Data from the
Arcata/Eureka
Airport SAO and
Crescent
City/McNamara SAO sites on the coast may be representative of coastal
locations including REDW1.
Twice daily upper air data collected at the Medford Oregon RAOB site about
150 km (100 mi) northeast of REDW1 is probably most representative of
conditions in Redwood National Park at higher altitudes. Lower altitudes at
coastal Park locations are more subject to marine penetration and coastal
inversions and may be better represented by sounding data from a coast site.
Wind Patterns
Prevailing winds at California coastal locations are generally from the
north or northwest throughout the year and especially in the summer months,
a consequence of the semi-permanent high pressure that lies off the Pacific
Coast. Southerly and easterly winds can occur during the winter, when the
Pacific High moves southward and weakens. This pattern is indicated in
monthly Arcata California Wind Roses, from
Arcata/Eureka
Airport SAO (Surface Airways Observation) NWS site on the California
coast about 80 km (50 mi) south of REDW1 and 40 km (25 mi) south of the
southern Park boundary.
Coastal locations are also subject to coastal land/sea breeze circulation,
with daytime sea breezes and weaker nighttime land breezes, especially near
corridors such as the Klamath and Smith Rivers that drain into the Pacific
Ocean near Redwood National Park. The REDW1 site is near the mouth of the
Smith River and so could possibly be influenced by diurnal valley flow from
the Smith River, with the potential for down valley drainage flow from the
east at night and early in the morning. Such a flow pattern could bring with
it emissions from inland locations, such as smoke from wildfires, that do
not extend to higher National Park elevations.
Potential local transport routes into the Redwood National Park Class I Area
include Bay Area emissions transported northward during southerly flow along
the coast, especially in the winter months, and valley flow from nearby
inland locations via the Smith and Klamath River valleys. This is in
addition to upper level transport from distant source regions on a synoptic
to global scale. The area is also subject to the influence of naturally
occurring marine aerosols.
Inversions/Trapping
Surface-based radiation inversions are infrequent in this coastal area. The
more common type of inversion, especially during the extended summer months
May to October, is the subsidence inversion over the eastern Pacific caused
by the persistent sub-tropical high-pressure system. Its base is typically
marked by a stratus cloud layer and is the height to which the atmosphere
pollutants can be mixed, the mixing height. High relative humidity below
drops drastically above. This deck of clouds and associated marine air
extends inland during the night and recedes towards the coast during the
day. This situation is typical of California coastal areas during the
summer. Vertical mixing is commonly restricted to 600 m (2,000 ft) or less,
which includes coastal National Park elevations. It may be marked in REDW1
data by a corresponding diurnal variation of aerosol concentrations and
marine components such as sea salt.
Climatological Statistics
Eureka
California Normals Means and Extremes from the
Arcata/Eureka
Airport SAO site are representative of coastal locations in Northern
California. National Park locations at higher elevations and further inland
may be better represented by data from the
Schoolhouse
California RAWS site. These and other
Northern California
Climate Summaries are available from the
Western Regional Climate Center.
Keywords