The Automated Surface Observing Systems (ASOS): Measure, Role in Weather Forecasting
|The Automated Surface Observing Systems (ASOS)
What is the Automated Surface observing System ASOS?
When you hear the high temperature of the day from your local TV weathercaster, that information probably came from an Automated Surface Observing Systems (ASOS) machine at your local airport.
An Automated Surface Observing System is a suite of weather sensors which measure, collect, and disseminate weather data.
This serves to help meteorologists, pilots and flight dispatchers prepare and monitor weather forecasts, plan flight routes, and provide necessary information for correct takeoffs and landings.
ASOSs are federally funded as a joint program between the National Weather Service, the Federal Aviation Administration, and the Department of Defense. ASOSs have been operational since the early 1990s and are located at over 900 sites nationwide.
These sites provide round the clock observations and are crucial for the safety of pilots, airplanes, and passengers. Since safety is the main concern with air travel, most ASOSs are located at airports to ensure that the most accurate conditions are being reported to the National Weather Service and air traffic controllers. Overall, ASOS sites’ continuous streams of data provide crucial observations to enable accurate forecasting by acting as a valuable climatological tool.
Some specific differences are a difference in wind observations. AWOS broadcasts true wind direction, while ASOS converts surface winds to magnetic direction. In addition precipitation type identification and thunderstorm reporting are different between the two.
|The ASOS program is a federally-funded, joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD). The systems serve as the United States' primary surface weather observing network, and their observations become useful when tropical cyclones are close to shore, have made landfall, and/or have moved inland.
What role does the ASOS play in weather forecasting?
With the largest and most modern complement of weather sensors, ASOS has significantly expanded the information available to forecasters and the aviation community. 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 will help the NWS to increase the accuracy and timeliness of its forecasts and warnings--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 networks. 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 are also available via a telephone dial-in port. ASOS observes, formats, archives and transmits observations automatically. ASOS transmits a special report when conditions exceed preselected weather element thresholds, e.g., the visibility decreases to less than 3 miles.
How does ASOS measure visibility?
ASOS-monitored weather conditions include:
An ASOS station is a land-based array of instruments and electronic sensors used to automatically process and create surface observations and measurement of the atmosphere in near real time. The systems provide 1-minute, 5- minute, hourly, and special observations 24 hours a day. A set of data is collected over time to provide a "representative" observation, and the system then applies mathematical logic, called algorithms, to the collected data to extrapolate the weather over a wider area.
- wind speed
- wind direction
- precipitation amount
- precipitation type
At present, automated weather stations are unable to report a variety of meteorological conditions. ASOS equipment is limited in that it can only detect weather that is directly over head, and hence, weather that has not encountered the sensors will not be measured. Some meteorological conditions
ASOS equipment can not measure include:
- shallow or patchy fog
- precipitation that is not in the form of rain or snow, such as hail and ice pellets
- multiple forms of precipitation falling at the same time
- in-cloud and cloud-to-cloud lightning
- clouds that are not directly above the station
- clouds that are more than 12,000 ft above ground level
- cloud type
Research is on-going to allow the automated stations to detect many of these weather conditions. All of these conditions are of interest to the meteorological community (and many of these can pose dangers to aircraft), and thus, most of the busier airports have part-time or full-time human observers which provide additional information to the automated weather stations' observations. ASOS equipment can also suffer mechanical breakdown, requiring repair or replacement. During system outages, human observers are also often required to supplement missing or non-representative observations. Researchers are working to produce more robust systems which are less vulnerable to natural damage, mechanical wear and icing.
With the largest and most advances weather sensors, ASOS machines have significantly expanded the information available to weather forecasters (especially with regards to observations at night). The ASOS program has also more than doubled the number of full-time surface weather observing locations. Getting more information on the atmosphere, more frequently, and from more locations is key to helping the NWS increase the accuracy of its forecasts and warnings.
The ASOS - Main Components
1. A sensor group, consisting of individual weather sensors and a Data Collection Package (DCP). The DCP continuously gathers and processes the raw data from the sensors and prepares it to be transferred to the ACU. This component is found at every ASOS site.
2. The Acquisition Control Unit (ACU), which is the Central Processing Unit for the ASOS site. It performs the final processing, formatting, quality control, and storage of the data, and makes it available to its users. The ACU is located inside a temperature controlled room near the sensor groups. This component is found at every ASOS site.
3. The Operator Interface Device (OID), which allows an observer to enter backup or augmented observations directly into the ACU. This component is found only at airports that offer backup support.
The ASOS sensor group is composed of the following
Wind Speed & Direction - A wind vane (for wind direction) and rotating anemometer cups (for wind speed). Wind gusts are measured by looking for winds that are stronger than the current wind and are sustained over a period of time.
Altimeter (Barometric pressure) - Two or three pressure transducers measure barometric pressure. The transducers must be within a certain range of each other for the pressure to be reported. The barometers are located in the bottom tray of the ACU.
Relative Humidity/Dew Point - A hygrothermometer is used to measure dewpoint. The process involves using a fan to draw ambient air into the housing and over a mirror that has been electronically cooled to a lower temperature. The cooling process continues until the dewpoint temperature is reached, at which time a layer of dew forms on the mirror. A laser beam and detector are used to detect dew formation. At that time, the mirror temperature is read and recorded as the dewpoint temperature.
Air Temperature - This measurement is made by a thermistor, a type of electronic thermometer. Readings are generally very accurate. It is located in the same place.
Precipitation Type & Amount- This is determined by a light-emitting-diode weather identifier, or LEDWI. This device measures the passage of particles through a sensor beam. Much of this instrument’s logic is tied into calculations, relating to fall velocity patterns. Snow falls slowly and makes one type of pattern, while rain falls at a faster rate, creating another signature. The LEDWI was designed only to report the occurrence of rain or snow at precipitation fall rates of .01 inch per hour or greater.
Visibility- This is determined by a scatter meter, which is a device that measures the amount of radiation scattered from a beam of light by particles in the air such as fog, rain, snow, or other airborne particulates. This yields a measurement of air clarity. The measurement is processed through algorithms designed to correlate the readings with familiar visibility values.
Cloud Height & Density- A laser beam ceilometer is used to measure cloud height, vertical visibility, and sky cover. A laser beam is pointed directly up in the sky; when clouds are overhead it reflects back to the sensor and is converted into a height measurement.
Lightning Detection- This sensor can detect cloud to ground and cloud to cloud lightning strikes. All strikes are counted, but only cloud to ground strikes are used to estimate the distance from the sensor. The strikes are then placed into either the 0 to 5 mile category, 5 to 10 mile category, or the 10 to 30 mile category.
Putting the Parts Together
Now that each part of the ASOS has been introduced, the full picture of the sensor suite can be seen below in Figure 8. The sensors relay the raw data to the DCP, which then transmits it to the ACU where the data is processed and formatted to be sent out.
|While not a perfect imitator of humans, ASOS is a valuable tool used by meteorologists and aviators alike. The constant monitoring that ASOS provides allows for around the clock information to aid in air travel safety. Forecasters and aviation employees must remember that even with all of ASOS’s strengths, it sees only a portion of the current atmosphere and effort should be taken to determine the full picture of the atmosphere from other sources.
What role does the Automated Surface Observing Systems (ASOS) play in weather forecasting? It is the nation’s primary weather-observing network. Which tool enhances weather forecasts by enabling monitoring, which is necessary for predicting global weather and environmental events?
What role does ASOS play in weather forecasting?
What role does the Automated Surface Observing Systems (ASOS) play in weather forecasting? It is a system of radar sensors used to track storms. It is the nation’s primary weather-observing network. It provides weather reports much like the National Weather Service.
What role does the Automated Surface observing System ASOS?
in-cloud and cloud-to-cloud lightning. clouds that are not directly above the station. clouds that are more than 12,000 ft above ground level. cloud type.
What is ASOS meteorology?
The Automated Surface Observing System (ASOS) program is a joint effort between the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD). The ASOS system serves as the nation’s primary surface weather observing network.
What is an ASOS system?
These automated systems collect observations on a continual basis, 24 hours a day. ASOS data are archived in the Global Surface Hourly database. Automated Weather Observing System (AWOS) units are operated and controlled by the Federal Aviation Administration.
What role does the Automated Surface Observing Systems (ASOS) play in weather forecasting?
It is the nation’s primary weather-observing network. Which tool enhances weather forecasts by enabling monitoring, which is necessary for predicting global weather and environmental events?
What is the Automated Surface observing Systems?
Automated Surface Observing System (ASOS) units are automated sensors provide local weather information to an air charter operator before and during their flight. In the United States, there are more than 900 ASOS units at various airports and other locations.
What do weather maps display weather stations?
A weather map is used to show weather facts about a specific place at a given time. It can show temperature, cloud coverage, rain or snow, wind, air pressure, humidity, and the direction a weather system is moving or expected to move.
What are the common components that make up the Automated Surface observing System ASOS and the Automated weather observing System AWOS )?
Automated Surface Observing System (ASOS)* These systems generate weather observations containing the following:
- Wind speed, direction, and gust information.
- Dew point.
- Altimeter setting.
- Cloud height and amount.
- Present weather.
- Precipitation accumulation.
What ASOS stands for?
ASOS stands for As Seen On Screen, with the original tagline saying ‘Buy what you see on film and TV’. That’s because when ASOS first launched more than two decades ago, it was a celebrity-linked clothing website.
What type of rain gauge is used in automated surface observation stations ASOS )?
The original precipitation accumulation measuring device used for automated airport weather stations was the heated tipping bucket rain gauge. The upper portion of this device consists of a 1-foot (0.30 m) diameter collector with an open top.
Why would you place an ASOS system in an open field?
The potential applications of the ASOS data go beyond that of providing basic weather information for aviation and forecasting; ASOS also will provide enhanced support to vital national programs such as public safety, hydrology, climatology, agriculture, and environmental protection, just to name a few.
How are computers used in producing weather forecasts?
How are computers used in producing weather forecasts? They compile data from multiple instruments. They collect air temperature and air pressure data. They eliminate the need for human meteorologists.
How does ASOS measure visibility?
The ASOS system shines a laser ceilometer into the sky to observe cloud layers. It takes a measurement every 30 seconds over a 30-minute period, then double-weighs measurements during the last 10 minutes so the computer can decide if the cloud layers are scattered, broken or overcast.
When was the Automated Surface Observing Systems invented?
Overview. The Automated Surface Observing System (ASOS) program was a joint effort between the Federal Aviation Administration (FAA) and the National Weather Service (NWS) to deploy a network of high-grade weather monitoring stations across the United States. In 1991, Systems Management Inc. (now All Weather Inc.)
What are radiosondes used for?
Radiosondes measure atmospheric pressure, air temperature, water vapor (humidity) and winds (speed and direction). Modern radiosondes contain a GPS receiver to calculate wind speed and direction, and a radio transmitter to send the data back to the ground.