Automated Surface Observing
Systems (ASOS) have been installed at over 850 locations throughout
the U.S. The ASOS program is a joint effort of the National Weather
Service (NWS), the Federal Aviation Administration (FAA), and the
Department of Defense (DOD). ASOS systems serve as the nation's primary
surface weather observing network. ASOS is designed to support weather
forecast activities and aviation operations and, at the same time,
support the needs of the meteorological, hydrological, and climatological
research communities.
With the largest and most modern complement of weather sensors,
ASOS significantly expands the information available to forecasters
and the aviation community. Since its nationwide implementation, the
ASOS network has more than doubled the number of full-time surface
weather observing locations. ASOS works non-stop, updating observations
every minute, 24 hours a day, every day of the year.
Getting more information on the atmosphere, more frequently and
from more locations is the key to improving forecasts and warnings.
Thus, ASOS information helps the NWS to increase the accuracy and
timeliness of its forecasts -- the overriding goal of the NWS modernization.
The primary concern of the aviation community is safety, and weather
conditions often threaten that safety. A basic strength of ASOS is
that critical aviation weather parameters are measured where they
are needed most: airport runway touchdown zone(s).
ASOS detects significant changes, disseminating hourly and special
observations via the network. Additionally, ASOS routinely and automatically
provides computer-generated voice observations directly to aircraft
in the vicinity of airports, using FAA ground-to-air radio. These
messages will also be available via a telephone dial-in port at the
ASOS.
ASOS Features
Observes, formats, archives and transmits observations automatically.
When preselected weather element thresholds are exceeded (e.g., the
visibility decreases to less than 3 miles), a "special" report
is transmitted.
-
Reports basic weather elements:
- Sky condition:cloud height and amount (clear, scattered, broken,
overcast) up to 12,000 feet
- Visibility (to at least 10 statute miles)
- Basic present weather information: type and intensity for
rain, snow, and freezing rain
- Obstructions to vision: fog, haze
- Pressure: sea-level pressure, altimeter setting
- Ambient temperature, dew point temperature
- Wind: direction, speed and character (gusts, squalls)
- Precipitation accumulation
- Selected significant remarks including- variable cloud height,
variable visibility, precipitation beginning/ending times, rapid
pressure changes, pressure change tendency, wind shift, peak
wind.
If you would like more information on ASOS , try the
ASOS Program Office. Also see more information regarding ASOS in
the
Change
Management Information web site.