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White Mountain Wilderness Area |
Visibility Monitoring Site
Name
IMPROVE:
WHIT1
Region
Mexican Highlands
Terrain
Terrain is shown in the 2 km terrain
map and
the 20 km terrain
map.
The White Mountain Wilderness Area occupies 48,366 acres at the crest of the
Sacramento Mountains in south-central New Mexico. The White Mountains run
generally north-south, with a steep and rugged west side and more gentle
east side with broad canyons. The east side generally forms the headwaters
of the eastward flowing Rio Bonito. Wilderness elevations range from about
1,850 m (6,070 ft) at lower slopes on the west side to 3,530 m (11,580 ft) at
the southern boundary ridge crest.
The IMPROVE monitoring site representing the White Mountain Wilderness is
WHIT1, located on a low ridge between Rio Bonito and Little Creek, near the
Sierra Blanca regional airport about 15 km east of the Wilderness at an
elevation of 2,050 m (6,724 ft).
Representativeness
The WHIT1 IMPROVE site is on a well-exposed low ridge at an elevation near
lower Wilderness elevations. It should be representative of Wilderness
locations, especially during downslope flow conditions that bring Wilderness
air towards the monitor via the Rio Bonito and Little Creek drainages.
Nearby Population/Industrial Centers and Local Sources
Nearby Meteorological Data Stations
Nearby meteorological monitoring network stations are shown in the data
network map.
Locations and data from nearby RAWS monitoring sites can also be accessed at
the RAWS station US Climate
Archive website. The Sierra Blanca Snotel site, with precipitation and
temperature data, is within the Wilderness boundary. The
Smoky Bear New
Mexico RAWS site is located < 5 km southeast of the Wilderness, near
Riudoso, at an elevation of 2,104 m (6,900 ft) and should provide good
Wilderness representation, including wind data. The
El Paso NWS
station also has long-term regional climate information.
For information on regional vertical structure, twice-daily upper air
sounding data are collected at the NWS upper air site at Santa Teresa New
Mexico, 200 km (120 mi) south-southwest. Vertical temperature profile data
from Santa Teresa are probably the best routinely collected and long-term
data representative of conditions at White Mountain Wilderness Area.
Wind Patterns
El Paso wind roses show regional wind patterns. Most of the year but
especially in winter there is a strong northerly component that varies
according to the position of the jet stream. During summer the jet stream
migrates further north than usual, so that synoptic westerly winds aloft are
weaker and more southeasterly winds dominate, coinciding 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. Southerly winds may also transport
airborne particulate material into the Wilderness from sources and source
regions to the south and southeast, including Mexican sources.
Locally, in the absence of strong regional pressure gradients, flow patterns
may be dominated by diurnal upslope/downslope flows. Downslope may bring
Wilderness air towards the WHIT1 monitoring site via the Rio Bonito and
Little Creek drainages. This Wilderness representative air may be replaced
during return upslope flow from the east.
Potential local transport routes into the White Mountain Wilderness Area
include southeasterly flow from northern Mexico and Gulf Coast areas, and
along the Tularosa Valley from the El Paso area to the south. Strong
springtime winds may bring dust from nearby desert areas.
Inversions/Trapping
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 south central
New Mexico region that includes the White Mountain Wilderness Area is near
the northern reaches of the south-central U.S. region of high stagnation
frequency, and according to long term data should typically have 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.
Surface radiation trapping inversions may occur at lower Wilderness
elevations, especially in the Rio Bonito valley. During such trapping
conditions, the WHIT1 IMPROVE site is probably within the inversion, hence
representative of trapped aerosol composition and concentration.
Climatological Statistics
Albuquerque
Normals Means and Extremes, and
El Paso NWS
station data, are representative of regional climatology at lower
elevations. Climate data nearer to the Wilderness is available from the
Smoky Bear New
Mexico RAWS site.
Meteorological Indicators for Local Sources
Keywords
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Last updated 15 November 2004
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