(Also see Yolla Bolly –
Middle Eel Wilderness Area)
Site Name
IMPROVE:
TRIN1 (Trinity)
Region
Klamath Mountains
Terrain
Terrain is shown in the 2 km terrain
map and the 20 km terrain
map.
The Marble Mountain Wilderness Area consists of ~ 200,000 acres of the
Marble Mountains of northern California. Its northern boundary is about 40
km south of the Oregon/California border. Its principal drainage is Wooley
Creek that flows westward into the Salmon River drainage and Pacific Ocean
via the Klamath River. Terrain is forested mountains, with highest
elevations 2,100 to 2,200 m. Lowest elevation is near 200 m on the western
boundary where Wooley Creek exits the Wilderness.
The IMPROVE site representing the Marble Mountain Wilderness Area, and the
Yolla Bolly – Middle Eel Wilderness Area ~100 miles to the south, is TRIN1
(Trinity), located midway between the two Wilderness Areas in the Trinity
Range. TRIN1 is situated on a ridgecrest of Pettijohn Mountain at an
elevation of 1,007 m. It is some 40 miles southeast of the Marble Mountain
Wilderness, in the Trinity River drainage, with an intervening 1,800 to
2,000 m crest line.
Representativeness
Because of distance and intervening terrain, TRIN1 may not be influenced by
the same local sources that impact the Marble Mountain Wilderness. In
particular, it may be more subject to Sacramento Valley emissions than the
Marble Mountain Wilderness. It should be representative of aerosol
characteristics in the Marble Mountain Wilderness during periods of more
uniform regional haze resulting from regional forest fire events or
transport from more distant source regions on a global scale.
Nearby Population/Industrial Centers and Local Sources
The closest source region with anthropogenic emissions that may contribute
to aerosol and haze at the TRIN1 IMPROVE site is the Sacramento Valley, with
its northern extreme at the communities of Redding and Red Bluff some 25
miles southeast of the site. The Sacramento Valley may thus provide a link
between TRIN1 aerosol measurements and emissions from the larger Sacramento
and San Francisco Bay areas during low level southerly flow. Marble Mountain
Wilderness Area is more distant, some 40 miles northwest of TRIN1 and 50 to
60 miles from the northern Sacramento Valley.
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. A nearby meteorological network station with good exposure and data
for correlating with aerosol measurements at TRIN1 is the
Lowden
California RAWS site south of TRIN1 at an exposed elevation of 951 m,
close to the TRIN1 elevation. The
Redding Airport
California RAWS site and
Redding
Municipal California SAO site provide meteorological data representative
of the northern Sacramento Valley.
The upper air site closest to the Yolla Bolly – Middle Eel and Marble
Mountain Wilderness Areas, and the TRIN1 IMPROVE site, is the Medford Oregon
RAOB site
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
Arcata California Wind Roses, from a coastal site about 50 miles
southwest of the Marble Mountain Wilderness Area and about 70 miles west of
the TRIN1 IMPROVE site.
In the interior northern Sacramento Valley, linked to the central California
valleys source region, flow and transport patterns are more in line with
valley orientation. At times, and especially during warm months from May to
October, there is a significant southerly component of flow in the
Sacramento Valley, evident in
Sacramento California
Wind Roses. Southerly flow from the Sacramento and Bay areas
is frequently caused or reinforced by a summertime thermal low over the
northern Sacramento Valley, a condition that may be the most conducive to
transport towards the TRIN1 monitoring site.
Potential local transport routes to the TRIN1 IMPROVE site include
Sacramento Valley emissions transported directly via diurnal upslope/downslope
flow, mixed upwards with afternoon mixing, or trapped regionally under a
persistent subsidence inversion. However, see Representativeness discussion.
Highest summertime measured concentrations at TRIN1 may also be associated
with regional forest fire events or transport from distant source regions.
Inversions/Trapping
Wintertime surface based inversions are common in the Sacramento Valley,
though they probably do not typically extend to the elevation of the TRIN1
monitoring site. Fall and winter are less likely to see Sacramento Valley
emissions impacting the TRIN1 site for this reason.
In the summer, the relatively shallow nighttime Sacramento Valley boundary
layer is generally mixed to heights of at least 1,000 m (> 3,000 ft) above
the ground on a typical summer day, close to the TRIN1 site elevation.
Persistent summer inversions are usually larger scale subsidence inversions
associated with the establishment of the semi-permanent Pacific
high-pressure system and can result in 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), well above the TRIN1 site elevation. Note that because
of distance and intervening terrain, Sacramento Valley inversions are much
less significant with respect to Marble Mountain Wilderness Area locations.
Climatological Statistics
Redding
California Normals Means and Extremes are representative of the northern
Sacramento Valley. Other
Northern California
Climate Summaries are available from the
Western Regional Climate Center.
Keywords