Chiricahua Wilderness Area
Terrain is shown in the
2 km terrain map and the
20 km terrain map.
The Chiricahua National Monument
and the Chiricahua Wilderness Area together comprise most of the Chiricahua
Mountains of southeastern Arizona. The Chiricahua Mountain Range is an
inactive volcanic region that forms part of the Mexican Highland
Physiographic Region. Chiricahua National Monument (12,984 acres) is at the
northern end of the range and consists of various peaks with elevations up
to 2100 m (7,000 ft). The much larger Chiricahua Wilderness Area (87,700
acres) covers most of the central part of the range and includes canyons
radiating outward from Chiricahua Peak, elevation 2,987 m (9,797 ft) to
lowest Wilderness elevations near 1,450 m (4,750 ft).
The IMPROVE monitoring site representing the Chiricahua National Monument
and Wilderness Area is CHIR1, located just outside of the western boundary
of the National Monument at an elevation of 1,570 m (5,150 ft). The
CASTNET monitoring site
CHA467, including meteorology monitoring, is nearby.
The IMPROVE monitoring site CHIR1 is at a relatively low elevation near the
mouth of one of the canyons that exit the National Monument towards the
large Sulphur Springs Valley to the west and is at a low elevation relative
to elevations within the Chiricahua NM and WA. It should be representative
of aerosol concentration and composition within the National Monument and
Wilderness Area except if inversion conditions at its lower elevation
isolate it from air at higher Monument and Wilderness elevations.
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 RAWS
station US Climate Archive sites. Data from the Chiricahua
CASTNET site, CHA467, includes
wind data. The site is at the same location as the IMPROVE site CHIR1 and
may be influenced by the same drainage flow described above. The
RAWS site is located just outside of the southwestern boundary of the
Wilderness Area and may provide good data representative of more southerly
portions of the Chiricahua Mountains. There are also several COOP sites in
The nearest routinely operated 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 of the region are characterized by
Tucson wind roses that
show prevailing east to southeasterly wind directions, with some strong
westerly winds during the spring. The Chiricahuas are well within the
influence of the North
American Monsoon that typically establishes itself in early July and
persists through mid- September. 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. From the
predominance of east to southeasterly winds apparent in the Tucson wind
roses it may be that this area is more subject to flow from the direction of
the Gulf of Mexico. The prevalence of easterly winds is also evident in 1995
– 2001 Chiricahua CASTNET wind roses
(wind roses provided as gif files with prefix CHA) from the CHA467 site.
These wind roses also show the diurnal effect of drainage and upslope winds
in canyon flow from the National Monument. Diurnal wind patterns can also be
seen in wind roses from the
RAWS site where diurnal upslope/downslope winds will be associated with
drainages extending outward from Chiricahua Peak in the center of the
Wilderness Area. These mountain flows occur locally in the absence of strong
regional pressure gradients.
Potential transport routes into the Chiricauha National Monument and
Wilderness Area include long distance transport via upward mixing from more
distant source regions and transport into the region via upper level flow.
Possible source regions include areas to the south and east, including the
Gulf Coast region and northern Mexico.
Wang and Angell,
1999 describe two regions of the U.S. with high frequencies of regional
stagnation events, in the southwest and south-central U.S. The southeastern
Arizona area that includes the Chiricahuas is between these two regions.
According to long term data the area typically has one to two stagnation
episodes per month from May to October, where an air stagnation episode is
defined as stagnation conditions that persist for 4 days or longer. 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.
The area may experience low-level surface-based radiation inversions. When
the Sulphur Springs Valley is within a low surface inversion, data from the
CHIR1 IMPROVE site may not be representative of aerosol characteristics at
higher Wilderness and National Monument elevations.
Tucson Normals Means
and Extremes are representative of regional climatology at lower
elevations. Tucson is located about 150 km (90 mi) to the west. More local
climatological data can be accessed at the
CASTNET site, CHA467, and
RAWS site. Other
Arizona Climate Summaries are available from the
Western Regional Climate Center.
Meteorological Indicators for Local Sources
Last updated 22 October 2004