Site Name
IMPROVE:
LAVO1
CASTNET: LAV410
Region
Cascade Range
Terrain
Terrain is shown in the 2 km terrain
map and the 20 km terrain
map.
The 105,800 acre Lassen Volcanic National
Park is located in northern California, at the southern extreme of the
Cascade Range. The Park consists of slopes and area surrounding Lassen Peak,
elevation 10,457 ft. Terrain of the National Park consists of several
volcanic cones in addition to Lassen Peak, and surrounding and intervening
terrain. Lowest elevations are near 5,600 ft at points where streams exit
the National Park. The entire National Park area is generally in terrain to
the east of the north end of the Sacramento Valley, and is thus subject to
upvalley flow from the south and west, the directions to northern Sacramento
Valley communities of Redding, Red Bluff, and Chico, roughly 50 mi to the
west, west-southwest, and south-southwest respectively. Typical northern
Sacramento Valley elevations are 150 to 200 m (500 – 600 ft), or about 5,000
ft lower than lowest Lassen Volcanic National Park elevations.
The IMPROVE site representing Lassen
Volcanic National Park is LAVO1 located near the northwest Park entrance
Ranger station, 25 yards southeast of the Fire Station, elevation 5,756 ft.
The site may be influenced by channeled flow in the Manzanita Creek drainage
that flows west from the Park and ultimately to the northern Sacramento
Valley. Local wind patterns can be seen in data from the
Lassen Volcanic National Park CASTNET
site, LAV410, located nearby.
Representativeness
The LAVO1 IMPROVE site is at an elevation of 5,756 ft, near the low end of
the range of National Park elevations. It should be representative of Park
locations in general. During surface inversion conditions it should still be
representative of lower Park elevations, and hence of worst (highest aerosol
concentrations) conditions. It is located within or near the Manzanita Creek
drainage that is a channel for nighttime drainage flow.
Lassen Volcanic National Park
Wind Roses show this bimodal pattern, and data from LAVO1 may show a
corresponding pattern indicating transport into and out of the National
Park.
Nearby Population/Industrial Centers and Local Sources
The closest source region with emissions that may contribute to aerosol and
haze in the National Park is the northern Sacramento Valley. The National
Park may also be linked to emissions from the Sacramento area 120 to 150
miles south, and from the San Francisco Bay area, during low level southerly
flow through the central valleys.
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 CASTNET site, LAV410,
should provide the best representation of meteorological conditions
concurrent with aerosol measurements at LAVO1. Meteorological data are also
available from the nearby
Manzanita Lake
California RAWS site.
Lassen Volcanic National Park is
midway between the Reno Nevada and Medford Oregon RAOB sites.
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 140 miles to the west.
In the interior central California Valleys (Sacramento and San Joaquin
Valleys) 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. Worst haze conditions at the LAVO1 IMPROVE
site, apart from smoke from regional forest fires, may result from such
southerly flow into the Sacramento Valley and upslope into the National
Park, especially in the summertime.
The National Park, along with Caribou
Wilderness Area and Thousand
Lakes Wilderness Area are in a region that is the low point separating
the Cascade and Sierra Nevada ranges. This could provide a natural conduit
for easterly low-level transport flow from sources east of the ranges,
during periods of persistent high pressure over the Great Basin for example.
However there are no major anthropogenic sources very close to the east.
Possible sources could include intermittent dry alkali lakes such as Honey
Lake and Alkali Lake in the Alturas-Susanville. Such incursions would be
rare and marked by concurrent east-west pressure gradient with strong winds,
and a distinct aerosol signature. It may be that such easterly flow
conditions could result in lowest aerosol concentrations at Lava Volcanic
National Park.
Wind patterns in the immediate vicinity of the LAVO1 IMPROVE site are shown
in Lassen Volcanic National Park
Wind Roses based on 7 years of meteorological data from the
LAV410 CASTNET site. These show a
local diurnal upslope (westerly) and downslope (easterly) pattern.
Potential local transport routes into
Lassen Volcanic National Park include Sacramento Valley emissions
transported directly via diurnal upslope/downslope flow, mixed upwards with
afternoon mixing and transported via prevailing upper level westerly winds,
or trapped regionally under a persistent subsidence inversion. This
transport and or trapping condition, for emissions from source regions to
the west in the northern Sacramento Valley and to the south near Sacramento,
occurs mainly in the summer. Highest summertime measured concentrations at
LAVO1 may also be associated with regional forest fire events.
Inversions/Trapping
Wintertime trapping inversions are likely at lower National Park elevations
and could restrict local emissions such as prescribed forest burning
emissions. Wintertime surface based inversions are also common in the
Sacramento Valley, the nearest significant source region for local
emissions, although at heights typically below National Park elevations.
Fall and winter are less likely to see Sacramento and Central Valley
emissions transported to National Park areas because of persistent low level
Sacramento Valley trapping inversions.
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, within the range of National Park
elevations represented by aerosol measurements at the LAVO1 IMPROVE site.
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 within the range of National Park elevations.
Climatological Statistics
Redding
California Normal Means and Extremes are representative of the climate
of the northern Sacramento Valley.
Manzanita
Lake California Climate Data are representative of conditions at the
LAVO1 IMPROVE site. Climatological statistics that include wind statistics
representative of the LAVO1 IMPROVE site can also be derived from
meteorological data from the LAV410
CASTNET site. Other
Northern California
Climate Summaries are available from the
Western Regional Climate Center.
Keywords