(Also, see Sequoia National Park Meteorological Characterization Page)
Site Name
IMPROVE:
SEQU1
Region
Sierra Nevada Range
Terrain
Terrain is shown in the 2 km terrain
map and the 20 km terrain
map. Kings
Canyon National Park consists of 459,994 acres of the western slopes of the
southern Sierra Nevada range. Sequoia and
Kings Canyon National Parks share a long boundary and are managed as one
park, with Kings Canyon NP to the north of Sequoia NP. Kings Canyon National
Park elevations range from around 1,200 m (4,000 ft) where westward flowing
streams exit the Park on the west side, to over 4,000 m (13,000 ft) along
the Sierra Nevada crest that forms the eastern boundary and culminates at
the peak of Mt. Whitney in Sequoia National Park boundary, elevation 4,417 m
(14,491 ft). Essential topographic features of Kings Canyon NP include the
Middle and South Forks of the Kings River that flow from the Sierra Nevada
crest and merge 10 km (6 mi) west of the National Park boundary, ultimately
flowing into Pine Flat Reservoir and opening up into San Joaquin Valley 40
km (25 mi) east of Fresno. The Middle Fork of Kings River flows through the
steep and narrow Kings Canyon, near 800 m (2,500 ft) deep and 3 to 4 km (1
to 2 mi) wide at the rim. Lowest elevations at the western boundary where
the two Forks of the Kings River exit the National Park are near 1,200 m
(4,000 ft). San Joaquin Valley is the source of most local emissions that
affect visibility within the Park.
The IMPROVE site representing Sequoia and Kings Canyon National Parks is
SEQU1, located in the Middle Fork of the Kaweah River drainage near its exit
from the Sequoia National Park south of Kings Canyon National Park. At an
elevation of 535 m (1,755 ft) it is about 65 m (210 ft) above the river.
There is a CASTNET site, SEK402,
with meteorological monitoring, located at elevation 1,225 m (4,018 ft) in
the lower East Fork of the Kaweah River, also near the western Sequoia
National Park boundary and about 15 km (10 mi) south of SEQU1 across the
ridge that separates the East and Middle Forks of the Kaweah River.
Representativeness
SEQU1 is situated near the bottom of one of the valleys that drain Sequoia
National Park on its west side, at the very lowest end of elevation ranges
within Sequoia National Park and well below lowest Kings Canyon National
elevations. It is well located for observing San Joaquin Valley emissions at
western Park boundaries, and emissions from more local sources, and may
represent highest aerosol concentrations and most severe visibility impacts
within Park boundaries. During inversion conditions it may not be as
representative of aerosol concentration and composition at highest Sequoia
and Kings Canyon National Park elevations that could be impacted by
emissions from more distant source regions on a synoptic to global scale. It
may be less representative of aerosol characteristics in the more distant
Kings Canyon National Park than in Sequoia National Park.
Nearby Population/Industrial Centers and Local Sources
Kings River Middle and South Forks exit Kings Canyon National Park some 40
km (25 mi) east of central San Joaquin Valley and 80 km east of Fresno, the
nearest San Joaquin Valley community. Lowest elevations of Kings Canyon NP
are around 700 m (2,300 ft) higher than lowest elevations of Sequoia NP and
the SEQU1 monitoring site and are near the upper end of the typical
summertime San Joaquin Valley mixing heights, so that SEQU1 aerosol data
should still represent maximum impact within the two Parks due to San
Joaquin Valley emissions.
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. With respect to aerosol data collected
at the SEQU1 IMPROVE site, the
Milk Ranch
California RAWS site is located near the ridge top southeast of SEQU1 at
an elevation of 1,898 m (6,225 ft) and may provide useful data on mesoscale
winds concurrent with SEQU1 aerosol monitoring. The Sequoia NP
CASTNET site, SEK402, is located
near the East Fork of the Kaweah River. Although it is not collocated with
SEQU1 it may provide hourly wind data that can be used to correlate SEQU1
data with the timing of upslope/drainage flow. It is 690 m (2,263 ft) higher
in elevation. Sequoia National Park wind roses (attached jpg files with
prefix SEK) from 5 years of data collected at SEK402 show the pronounced
seasonal and diurnal channeling pattern. Timing of upslope transport of
Valley emissions into Kings Canyon National Park may be different because of
its higher elevation and further distance from Valley sources.
Upper air data is collected twice daily at the Oakland RAOB site.
Wind Patterns
Synoptic winds are influenced by the orientation of the San Joaquin Valley
and at the mesoscale are generally northwesterly (from the northwest), with
a high frequency of southeast winds in the winter. This pattern is evident
in monthly Fresno California Wind Roses. Locally and in the absence of synoptic forcing, winds at the SEQU1 site
should have a bimodal pattern as a result of steering by the Middle Fork of
the Kaweah valley including a significant diurnal mountain/valley component,
with easterly (from the east) nighttime drainage flow and westerly daytime
upslope flow from the direction of Fresno and Visalia in the San Joaquin
Valley. This pattern is evident in Sequoia National Park wind roses
(attached gif files with prefix SEK) from the Sequoia NP
CASTNET site, SEK402, located at a
similar location close to the East Fork of the Kaweah River, the next
drainage to the south. Upslope/downslope flow could transport San Joaquin
Valley air to the IMPROVE site during the afternoon and evening, with return
flow at night and early morning.
Potential local transport routes into Kings Canyon National Park include San
Joaquin Valley emissions transported directly via diurnal upslope/downslope
flow, mixed upwards with afternoon mixing, or trapped regionally under a
persistent subsidence inversion. Transport corridors for San Joaquin Valley
emissions into Kings Canyon National Park are primarily the Middle and South
Forks of the Kings River from the direction of Fresno. Synoptic westerly
flow could also cause transport into the National Park, including into
higher elevations near the crest of the Sierra Nevada range. During
infrequent east wind conditions, with high pressure over the Great Basin and
low pressure off the California Coast, emissions from Owens Valley and Owens
Lake east of the Sierra Nevada crest may be mixed upwards and impact highest
elevations on the west side of the National Park. At times this may spill
over into headwater areas west of the Sierra Nevada crest, though still
probably not discernible at the SEQU1 monitoring site.
Inversions/Trapping
The steep Kings Canyon may be subject to canyon inversions and trapping of
pollutants during periods of regional high pressure and stagnation,
especially in the winter. Wintertime surface based inversions are also
common in the San Joaquin Valley, although at heights typically below
National Park elevations. In the summer, the relatively shallow nighttime
San Joaquin 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, near the
lower end of Kings Canyon National Park elevations. 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). Both types of
inversions, surface radiation and elevated subsidence, can occur during the
fall.
Climatological Statistics
Huntington
Lake Climate Data
Fresno
California Normal Means and Extremes are representative of climate
characteristics in San Joaquin Valley. Climate data from the Sequoia NP
CASTNET site, SEK402, and from the
Milk Ranch
California RAWS site should be representative of lower Kings Canyon
National Park elevations on the west side. Other
Northern California
Climate Summaries are available from the
Western Regional Climate Center.
Keywords