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Zion National Park |
Site Name
IMPROVE:
ZION1
and
ZICA1
Region
Colorado Plateau
Terrain
Terrain is shown in the
20 km ZION1
terrain map.
Zion National Park is located in southwestern Utah. The main part of the
National Park is comprised of Zion Canyon, near the headwaters of the Virgin
River. There is also a section of the park, called Kolob Canyons, to the
northwest of the Zion Canyon section, which is comprised primarily of Kolob
canyon, which drains into Kanarra Creek and thence south into the Virgin
River. The two sections thus constitute two separate tributaries of the
Virgin River, separated by high terrain, and the Kolob Canyon section is
generally higher in elevation, and more rugged, than the Zion Canyon
section. The two sections are characterized by steep canyons and badlands.
The
ZION1 monitoring site is at the northwestern edge of the park, near the
mouth of Kolob Canyon, at an elevation of 1,545 m (5,068 ft), and close to
Interstate Highway 15, a heavily traveled freeway connecting the Las Vegas
and Salt Lake City areas. A second monitoring site,
ZICA, was installed in
January 2003 at a location nearer to the Zion Canyon section.
Representativeness
Aerosol data collected at the ZION1 monitoring site is close to the
Interstate 15 corridor. It may be reasonably representative of lower
elevations of the Kolob Canyons park section. It is of questionable
representation for the main Zion Canyon park section, which is separated
from it by high terrain. The more recently installed ZICA site should
provide better representation of the main Zion Canyon section
Nearby Data Stations
Climate data is available from the
New Harmony COOP
site, located close to the ZION1 aerosol site and representative of the
ZION1 site, although other data sites may better represent conditions in
enclosed canyon sections, and higher elevations, of the National Park. Other
local data stations are shown in the data network
map, and many of these can
be referenced at the
US Climate Archive and the
RAWS station US Climate Archive sites for western U.S. These sites
include length of record information and wind rose generation capability.
Wind Patterns
Long-term wind roses from the Cedar City NWS site for
January,
April,
July, and
October should be regionally representative of exposed areas, and should
also be generally representative of seasonal wind patterns at the ZION1
monitoring site, since they are both located in the I15 corridor, with Cedar
City ~ 30 km (20 mi) north of the monitoring site. These wind roses show the
preponderance of southerly flow, especially in the summer, with significant
frequencies of northerly wind directions in other seasons. This may have
implications for transport flow from the Las Vegas and the Salt Lake City
areas, into canyon areas via the Virgin River drainage. Wind directions at
the ZICA site may have an additional component of canyon winds from the
mouth of Kolob Canyon, as it is located fairly close to the Canyon exit.
Wind roses for the Zion Canyon RAWS site, and information on length of
record, are accessible at the
RAWS station US Climate Archive site.
Wind patterns at most lower elevation locations in the National Park may be
greatly different from these wind roses. Most areas, especially at lower
elevations, are subject to diurnal upslope/downslope flow patterns typical
of steep canyons.
Inversions/Trapping
Canyons of Zion National Park are generally steep and constricted, hence
susceptible to trapping inversions. In these situations, aerosol
measurements from ZION1 will probably not represent conditions in the main
Zion Canyon portion of the National Park, being influenced more by trapped
pollutants in the basins and valleys in the New Harmony and Cedar City
areas. ZION1 measurements will be more representative of the Kolob Canyon
section of the Park than of the Zion Canyon section. During large scale
inversions, such as subsidence inversions associated with buildup and
stagnation of synoptic high-pressure ridges over periods of a few days or
longer, conditions may be more uniform within the Park. These are most
likely to occur during the extended summer (May - October), when pressure
and temperature gradients in the region are weakest, and wind circulations
therefore weaker.
Climatological Statistics
Climate data is available from the
New Harmony COOP
site. This site is located close to the ZION1 aerosol site and is
representative of climate conditions at the ZION1 site.
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