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Yellowstone National Park |
(Also see Red Rock Lakes Wilderness Area,
Grand Teton National Park, and
Teton Wilderness Area)
Site Name
IMPROVE:
YELL2
CASTNET: YEL408
Region
Central Rockies
Terrain
Terrain is shown in the 2 km terrain map and the 20 km terrain map.
Yellowstone National Park occupies
2,221,766 acres in northwestern Wyoming, overlapping into Montana and Idaho.
Terrain has been characterized as broad dissected plateau interrupted by
several mountain ranges. Highest relief is along the northern and eastern
borders. Elevations range from 1,620 m (5,314 ft) where the Yellowstone
River exits the Park on the north boundary, to 3,000 m (9,840 ft) and higher
at mountain summits on the eastern and northern boundary. Highest elevation
is 3,462 m (11,358 ft) at the summit of Eagle Peak on the southeastern Park
boundary.
The IMPROVE site representing Yellowstone National Park, as well as Grand
Teton National Park and Teton Wilderness Area to the south and Red Rocks
Lake Wilderness Area to the west, is YELL2, located close to the north shore
of Yellowstone Lake in the center of the National Park. The site elevation
is 2,425 m (7,954 ft), 67 m (220 ft) above Lake elevation of 2,358 m (7,733
ft). The Yellowstone National Park
CASTNET site YEL408 is nearby, elevation 2,400 m (7,872 ft), 42m (138
ft) above Lake level.
Representativeness
YELL2 is near the center of the National Park and hence representative. It
may at times be decoupled from air at higher elevations when contained
within a surface inversion over Yellowstone Lake.
Nearby Population/Industrial Centers and Local Sources
The National Park is remote from any major source regions. The nearest
population centers are the Idaho Falls/Pocatello Idaho area 200 km (120 mi)
southwest of YELL2 in the eastern Snake River Plain region of Idaho, and
Helena Montana 225 km (140 mi) north-northwest of YELL2. The Naughton and
Bridger Power Plants in southwestern Wyoming are ~ 300 km (200 mi) to the
south. Nearby emission sources may include smoke from natural and
anthropogenic burning. Highest concentrations from local/regional sources
may occur during regional wildfire events. A wintertime study of snowmobile
emissions indicated that particulate emissions from 2-stroke snowmobile
engines have a potential for visibility impacts in the Yellowstone Park
airshed (Sive et al, 2003). The YELL2 site is near the Lake Ranger Station,
one of the sampling sites for the study. References to this and other
related studies are available at the
Montana
DEQ Clean Snowmobile Facts web page.
Nearby Meteorological Network Monitoring Stations
Nearby meteorological monitoring network stations are shown in the data
network map and at the
US Climate Archive
and RAWS station US Climate
Archive sites. The Yellowstone
National Park CASTNET site YEL408 is in close proximity to YELL2 and
should provide the best available representation of local surface
meteorology concurrent with aerosol monitoring. Historical data for regional
first order NWS stations are available via the
EPA Technology Transfer
Network website.
The closest upper air site is at Riverton Wyoming (RIW). This and other
upper air sites are accessible via the
University of Wyoming Dept
of Atmospheric Science web page.
Wind and Transport Patterns
Regionally, wind patterns and transport flows are dominated by westerly
synoptic flows, with frequent easterly flows from the north-central U.S. and
Canadian interior in the winter. Monthly
Pocatello Idaho wind roses
are indicative of this pattern, with southwesterly flow predominant at this
surface station and a significant northeasterly component in the winter.
Note that these surface wind patterns may differ from upper level winds
because of local terrain effects such as the eastern Snake River Plain where
Pocatello is located. Aerosol transport from distant source regions to the
vicinity of Yellowstone National Park and the YELL2 monitoring site will
most often be via the upper level predominantly westerly winds.
Locally, YELL2 is near the northern shore of Yellowstone Lake. Local surface
wind patterns are shown in
Yellowstone National Park wind roses based on 1996-2003 data from the
Yellowstone National Park CASTNET
site YEL408. These show predominantly southwesterly flow, especially for
higher wind speeds. Light wind speeds have a significant north-northwest
component associated with drainage flow and a possible land/lake breeze from
higher terrain north of the site during nighttime. Annual daytime strong
winds are almost exclusively from the southwest in line with prevailing
upper level synoptic flow, and light winds from the south to southeast the
probable direction for upslope and possible lake breeze flow.
Inversions/Trapping
The YELL2 IMPROVE site is sufficiently close to the level of Yellowstone
Lake to be beneath frequent prolonged wintertime surface trapping inversions
during periods of cold temperatures and regional high pressure. During these
inversions episodes the site is subject to the buildup of emissions from
local and nearby sources while decoupled from upper level transport flow and
higher Park elevations. In the summer regional subsidence inversions during
periods of high pressure and stagnation can result in widespread aerosol
buildup over periods of days. High summertime aerosol concentrations at
YELL2 may result from more regional sources such as western wildland fires
in conjunction with such episodes.
Climatological Statistics
Climatological data derived from
Yellowstone NP CASTNET site YEL408 data should be most representative of
YELL2.
Other Wyoming
Climate Summaries
Idaho Climate
Summaries and
Montana Climate Summaries are available from the
Western Regional Climate Center.
Meteorological Indicators for Local Sources
Keywords
Reference
Sive, B., D. Shively, and B. Pape, 2003. Spatial Variation of Volatile
Organic Compounds Associated with Snowmobile Emissions in Yellowstone
National Park. University of New Hampshire Climate Change Research Center.
Submitted to the National Park Service, US DOI. October 25, 2003.
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Last updated 16 December 2004
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