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Pine Mountain 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 Pine Mountain Wilderness Area in central Arizona 100 km north the
Phoenix/Mesa metropolitan area. Like the Mazatzal Wilderness 25 km to the
east across the Verde River the Pine Mountain 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
consists of slopes and canyons extending downwards from the pinnacle of Pine
Mountain, elevation 2,077 m (6,814 ft). Lowest elevations near 1,200 m (4,000
ft) are along the southeastern Wilderness boundary.
The IMPROVE monitoring site representing the Pine Mountain Wilderness Area
is the Ike’s Backbone site,
IKBA1. Ike’s Backbone is a promontory above the
Verde River that extends into the northwestern extreme of the Mazatzal
Wilderness. From IKBA1 the Pine Mountain Wilderness is seen to the southwest
across the Verde River valley.
Also see Mazatzal Wilderness Area.
Representativeness
IKBA1 should be very representative of aerosol concentration and composition
within the Pine Mountain Wilderness Area.
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 the Childs COOP site is just outside
the northeastern boundary at an elevation of about 800 m. The nearest site
that includes wind data is the
Verde 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.
South and southwesterly regional transport winds may also carry emissions
from sources and source regions southwest of the Wilderness, such as the
Phoenix/Mesa metropolitan area, into higher terrain of the Pine Mountain
Wilderness.
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 sources and source regions to the
south including Phoenix/Mesa. Locally within the Wilderness, upslope/downslope
patterns will be up and down the slopes and valleys extending down from Pine
Mountain on all sides.
Potential local transport routes into Pine Mountain 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 higher level flow.
Inversions/Trapping
The southwestern U.S. region that includes the Pine Mountain Wilderness is
subject to frequent stagnation events. In the 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. Pine Mountain 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 and transports
them to Wilderness elevations.
Climatological Statistics
Phoenix Normals
Means and Extremes are representative of regional climatology at lower
elevations. The
Verde RAWS Site, or the Childs COOP site provide long-term data that may
be more representative of Wilderness locations.
Meteorological Indicators for Local Sources |
Last updated 17 December 2004
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