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Mazatzal Wilderness Area |
Site Name
IMPROVE:
IKBA1 (Ike’s Backbone)
Region
Mexican Highlands
Terrain
Terrain is shown in the 2 km terrain
map and the 20 km terrain
map.
The Mexican Highlands is a rugged escarpment that forms the southern limit of the
Colorado Plateau.
The Mazatzal Wilderness Area is in central Arizona, about 60 km (40 mi)
northeast of the Phoenix/Mesa metropolitan area. The Wilderness is within a
mountainous transition zone between the uplifted Mexican Highlands and Colorado
Plateau to the northeast and the lowlands around Phoenix and Mesa. It is
comprised in its western half of the south-flowing Verde River canyon and
valley. The Verde is designated as a Wild River where it flows through the
Wilderness. The Wilderness is traversed in its northern 1/3 by the
west-flowing East Verde River. The confluence of these two rivers, which
form the two major river canyons of the Wilderness, is enclosed within the
northwestern portion of the Wilderness. Most of the eastern and central
portions, south of the East Verde, consist of narrow vertical canyons cut
into terrain that slopes generally to the southwest. Elevations range from
640m (2,100 ft) at Sheep Bridge in the southwest to 2,409 m (7,903 ft) on Mazatzal Peak in the southeast corner of the Wilderness.
The IMPROVE monitoring site representing the Mazatzal Wilderness Area is the
Ike’s Backbone site, IKBA1. Ike’s Backbone is a promontory above the Verde
River that extends into the Wilderness at its northwestern extreme. From
IKBA1 the Wilderness vista is to the southeast, across the Verde towards the
higher terrain. At an elevation of 1,303 m (4,274 ft) it is midway in the
range of elevations found over most of the Wilderness. IKBA1 also has a
vista to the southwest across the Verde River towards the Pine Mountain
Wilderness Area.
Also see Pine Mountain Wilderness Area.
Representativeness
IKBA1 should be very representative of aerosol concentration and composition
across long site paths from view locations for the Mazatzal Wilderness Area.
It may not be as representative of conditions at interior valley and canyon
locations if and while they are within strong shallow surface based
inversions.
Nearby Population/Industrial Centers and Local Sources
Nearby Meteorological Data 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.
These show no meteorological sites within the Wilderness boundary, though
there are several COOP stations (Natural Bridge, Irving, Fossil Springs)
with temperature and precipitation data nearby. The nearest site that
includes wind data is the
Payson RAWS Site.
The nearest upper air site is the Tucson RAOB site, which conducts
atmospheric soundings twice daily. Sounding data from Tucson should be
representative of regional upper air structure.
Wind Patterns
Wind patterns of the region are characterized by predominantly westerly
winds except during spring and summer.
Phoenix wind roses show the
prevailing westerly to southerly wind direction predominance on an annual
basis. A seasonal shift in wind from a westerly direction to a more
southerly direction, not clearly evident in the Phoenix wind roses which may
be steered locally, typically establishes itself in early July and persists
through mid-September and is associated with the
North American
Monsoon. During this period moisture bearing winds move into the region
from the southwest at the surface, from the Gulf of California, and aloft
from the southeast, from the Gulf of Mexico. Convective instability
associated with surface heating of the moist air, combined with orographic
uplift as air is transported towards higher terrain in the direction of the
Mexican Highlands, produces frequent convective precipitation events often
associated with intense rainfall, lightning, hail, and damaging winds.
Strongest thunderstorms are often found in the mountainous regions near the Mazatzal Wilderness. These thunderstorms are often accompanied by strong
winds and brief periods of blowing dust prior to the onset of rain. South
and southwesterly regional transport winds may also carry emissions from
nearby sources and source regions southwest of the Wilderness, such as the
Phoenix/Mesa metropolitan area, into higher terrain of the Mazatzal
Wilderness and Mexican Highlands.
Transport flow into the Wilderness may also occur with more quiescent
regional flow conditions as a result of mesoscale upslope flow in the Verde
River valley and surrounding terrain from nearby sources and source regions
to the southwest including Phoenix/Mesa. Locally within the Wilderness,
upslope/downslope patterns will be steered according to orientation of local
terrain.
Potential local transport routes into Mazatzal Wilderness include low-level
mesoscale upslope flow from sources and source regions to the southwest,
perhaps along the Verde River valley and mixed upwards to high elevations of
the Wilderness, and long distance transport via upward mixing from more
distant source regions in the southwest and transport into the region via
upper level flow.
Inversions/Trapping
The southwestern U.S. region that includes the Mazatzal Wilderness is
subject to frequent stagnation events. In central Arizona long-term data
indicate an average of at least one stagnation episode per month from May to
October, where an air stagnation episode is defined as stagnation conditions
that persist for 4 days or longer (Wang
and Angell, 1999). During this period, pressure and temperature
gradients in the region are weakest, and wind circulations weakest.
Subsidence inversions during these conditions may trap regional haze with
buildup over periods of several days.
Surface based radiation inversions in the Phoenix/Mesa valley can occur,
especially in the wintertime. Wilderness locations are likely above this
surface inversion layer most of the time, but may be impacted if mixing
caused by surface heating lifts trapped pollutants to Wilderness elevations.
At lower canyon elevations within the Wilderness, locally generated aerosols
may be trapped within smaller scale radiation inversions.
Climatological Statistics
Phoenix Normals
Means and Extremes are representative of regional climatology at lower
elevations. Within the Mazatzal Wilderness, the
Payson RAWS Site,
or COOP sites given in the Nearby Meteorological Data Stations section,
provide long-term data that may be more representative of Wilderness
locations.
Meteorological Indicators for Local Sources
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Last updated 13 November 2004 |