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1092:) units are mostly operated, maintained and controlled by state or local governments and other non-federal entities and are certified under the FAA non-federal AWOS Program. The FAA completed an upgrade of the 230 FAA owned AWOS and former automated weather sensor systems (AWSS) systems to the AWOS-C configuration in 2017. The AWOS-C is the most up-to-date FAA owned AWOS facility and can generate METAR/SPECI formatted aviation weather reports. The AWOS-C is functionally equivalent to the ASOS. FAA owned AWOS-C units in Alaska are typically classified as AWOS-C IIIP units while all other AWOS-C units are typically classified as AWOS III P/T units.
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1691:. The sensor is based on a solid state capacitive relative humidity element that incorporates a small heater so that the sensing element is always above the ambient temperature, eliminating the formation of dew or frost. The sensor reports directly in dew point through a calculation based on measured relative humidity and the measured temperature of the heated capacitive element.
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to measure wind speed and direction. This system is simple in design: the wind spins three horizontally turned cups around the base of the wind vane, providing an estimation of the wind's speed, while the vane on top turns so that the face of the vane offers the least resistance to the wind, causing
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the station (TS). Lightning strikes more than 5 miles (8.0 km) but less than 10 miles (16 km) from the station result in a report of a thunderstorm in the vicinity of the station (VCTS). Lightning more than 10 miles (16 km) but less than 30 miles (48 km) from the station results
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To report freezing rain, the system combines the sensor output from the freezing rain sensor with data from the LEDWI. The LEDWI must provide a positive indication of unknown precipitation or rain before the system can transmit a report of freezing rain. If the LEDWI reports either no precipitation
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In contrast, the dew point measurement is considerably more complex. The original dew point sensor deployed on ASOS systems utilized a chilled mirror that is cooled to the point where a fine film of condensation forms on the mirror's surface. The temperature of the mirror at this condition is equal
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is pointed upward, and the time required for reflected light to return to the station allows for the calculation of the height of the cloud base. Because of the limited coverage area (the laser can only detect clouds directly overhead), the system computer calculates a time-averaged cloud cover and
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Forward scatter sensors are more popular due to their lower price, smaller size and lower maintenance requirements. However, transmissometers are still used at some airports as they are more accurate at low visibilities and are fail-safe, i.e. in case of failure report visibility lower than actual.
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These systems generally report at hourly intervals, but also report special observations if weather conditions change rapidly and cross aviation operation thresholds. They generally report all the parameters of the AWOS-III, while also having the additional capabilities of reporting temperature and
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Automated stations can also suffer from mechanical breakdown, requiring repair or replacement. This can be either due to physical damage (either natural or human caused), mechanical wear, or severe icing during winter weather. During system outages, human observers are often required to supplement
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Because many of these can pose dangers to aircraft and all of these are of interest to the meteorological community, most of the busier airports also have part-time or full-time human observers who augment, or provide additional information to, the automated airport weather station's observations.
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However, some stations now have their own lightning sensor to actually measure lightning strikes at the site rather than requiring an external service. This thunderstorm sensor works by detecting both the flash of light and momentary change in the electric field produced by lightning. When both of
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to another, which varies depending on - among other factors - the wind speed. The transit time is measured in both directions for several (usually two or three) pairs of the transducer heads. Based on those results, the sensor computes wind speed and direction. Compared to mechanical sensors, the
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are mounted so they measure a high degree of reflected light when the mirror is clear (direct) and scattered light when the mirror is clouded with visible condensation (indirect). With the formation of condensation on the mirror, the degree of cloudiness of the mirror surface increases with the
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Most aviation weather stations use two (required for an AWOS) or three independent pressure transducers. The transducers may or may not share their associated tubing and external ports (designed to minimize effect of wind/wind gusts). Should the reported pressures differ by more than a preset
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that operates much like a thermocouple in reverse, producing a heating or cooling effect. When the sensor is first activated, the mirror is clear. As the mirror surface temperature is cooled to the dew point temperature, condensations forms on the mirror. The electronics continuously tries to
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Also, custom configurations such as AWOS AV (AWOS A parameters plus visibility) are possible. Non-certified sensors may be attached to AWOS systems, but weather data derived from those sensors must be clearly identified as "advisory" in any voice messages and may not be included in any METAR
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stabilize the signal levels to the power amplifier to maintain the mirror temperature at the dew point. If the dew point of the air changes or if the circuit is disturbed by noise, the loop makes the necessary corrections to restabilize at the dew point and maintaining continuous operation.
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lightning strikes. Data from the detection grid is fed into ALDARS, which in turn sends messages to each automated airport station informing it of the proximity of any lightning strikes. Lightning strikes within 5 miles (8.0 km) of the station result in a report of a
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In steps of 50 m when the visibility is less than 800 m; in steps of 100 m when it is 800 m or more, but less than 5 km; in kilometer steps when the visibility is 5 km or more but less than 10 km; and 10 km when visibility is 10 km or
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is reported, depending on the exact visibility. Fog is reported when visibility is 1/2 mile or less; mist is reported for visibilities greater than 0.5 miles (0.80 km) but less than 7 miles (11 km). If the temperature is below
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these are detected within a few milliseconds of each other, the station registers a possible lightning strike. When a second possible lightning strike is detected within 15 minutes of the first, the station records a thunderstorm.
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The forward scatter sensor uses a beam of infrared light which is sent from one end of the sensor toward the receiver, but offset from a direct line to the receiver by a certain angle. The amount of light scattered by
1557:. If precipitation is determined to be falling, but the pattern is not conclusively identified as either rain or snow, unknown precipitation is reported. Automated airport weather stations are not yet able to report
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1321:) units are operated and controlled cooperatively in the United States by the NWS, FAA, and DOD. After many years of research and development, the deployment of ASOS units began in 1991 and was completed in 2004.
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In the United States, the AWOS/ASOS data acquisition system (ADAS), a computer system run by the FAA, polls the systems remotely, accessing the observations and disseminating them worldwide electronically in
1631:, which is reported to external users. To compensate for the danger of rapidly changing sky cover, the averaging is weighted toward the first 10 minutes of the 30-minute averaging period. The range of the
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missing or non-representative observations from the automated station. Research is also ongoing to produce more robust systems which are less vulnerable to natural damage, mechanical wear and icing.
1577:, the system uses the reported temperature and dew point to determine an obscuration to vision. If relative humidity is low (i.e., there is a large difference between the temperature and dew point),
1758:. The upper portion of this device consists of a 1-foot (0.30 m) diameter collector with an open top. The collector, which is heated to melt any frozen precipitation such as snow or
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where precipitation continuously accumulates within the collector, and as the weight increases, precipitation is recorded. Only select NWS ASOS units have been equipped with the AWPAG.
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to the dew point temperature. The hygrometer measures the dew point by directing a light beam from a small infrared diode to the surface of the mirror at an angle of 45 degrees. Two
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Current sensors are capable of reporting visibility in a wide range. For aviation purposes, the reported values are rounded down to the nearest step in one of the following scales:
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In a transmissometer, a beam of visible light is transmitted from its transmitter to receiver head. The extinction coefficient is derived from the amount of light lost in the air.
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direct transistor receiving less light and the indirect transistor more light. The output from these photo transistors controls the mirror cooling module which is an electronic
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Unlike all other measurements, which are made between 3 and 9 feet (0.91 and 2.74 meters) above the ground, wind speed and direction are measured at 30 feet (9.1 meters).
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Older AWOS systems used a lithium chloride dew point sensor. Current AWOS systems use capacitive relative humidity sensors, from which dew point is calculated.
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into one compartment of the bucket until 0.01-inch (0.25 mm) of water (18.5 grams) is accumulated. That amount of weight causes the bucket to tip on its
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Automated airport weather stations do not have a separate sensor for detecting specific obscurations to vision. Instead, when visibility is reduced below 7
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beam (approximately 50 millimeters in diameter) and determines from a pattern analysis of the particle size and fall velocity whether the precipitation is
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or snow, the system will ignore the input from the freezing rain sensor. The sensor is designed to detect and report icing from all weather conditions.
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The measurement of temperature is simple compared to the dew point. Operating under the principle that electrical resistance varies with temperature, a
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In the United States, there are several varieties of automated weather stations that have somewhat subtle but important differences. These include the
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and received by the receiver determines the extinction coefficient. This is then converted to visibility using either Allard's or
Koschmieder's law.
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in the vicinity of an airport. The message is updated at least once per minute, and this is the only mandatory form of weather reporting for an AWOS.
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measures the ambient air temperature. The current ASOS thermometer is designated the HO-1088, though some older systems still utilize the HO-83.
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1951:(ATIS). Most automated weather stations also have discrete phone numbers to retrieve real-time observations over the phone or through a modem.
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1721:. To ensure safe separation from terrain and other obstructions, high degree of accuracy and reliability is required from a pressure sensor.
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is up to 25,000 feet (7,600 m) depending on the model. Clouds above that height are not detectable by automated stations at present.
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format, and typical reporting frequencies are once every 20 minutes. This option is only available for AWOS III or IV systems (see below).
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The new generation of sensors use sound waves to measure wind speed and direction. The measurement is based on the time it takes for an
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2553:"AUTOMATED SURFACE OBSERVING SYSTEM (ASOS) RELEASE NOTE SOFTWARE VERSION - 2.7B All Weather Precipitation Accumulation Gauge (AWPAG)"
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network of climate stations. Because of this, not every ASOS is located at an airport; for example, one of these units is located at
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Altimeter setting is calculated based on barometric pressure, site elevation, sensor elevation and - optionally - air temperature.
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2119:"AC 150/5220-16E - Automated Weather Observing Systems (AWOS) for Non-Federal Applications - with Change 1 – Document Information"
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Due to problems with the chilled mirror sensor, NWS ASOS sites now use
Vaisala's DTS1 sensor, which measures humidity only via
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55:
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offer several advantages such as no moving parts, advanced self-diagnostic capabilities and reduced maintenance requirements.
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At present, automated airport weather stations are unable to report a variety of meteorological conditions. These include:
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2497:"A NEW LOW MAINTENANCE DEW POINT SENSOR FOR THE NATIONAL WEATHER SERVICE (NWS) AUTOMATED SURFACE OBSERVING SYSTEM (ASOS)"
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Because of problems the heated tipping bucket has with properly measuring frozen precipitation (particularly snow), the
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The original precipitation accumulation measuring device used for automated airport weather stations was the heated
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M1/4 (less than 1/4 mile), 1/4, 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4, 5, 7, 10 and 10+ (greater than 10 miles)
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NWS and FAA ASOS stations and most of new AWOS installations are currently equipped with ultrasonic wind sensors.
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maximum, the pressure values are discarded and altimeter setting is not reported or is reported as "missing."
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1778:, dumping the collected water and moving the other chamber under the funnel. The tipping motion activates a
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There also are sensors that, to a certain degree combine a transmissometer with a forward scatter sensor.
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AWOS III P/T: all AWOS III parameters, plus precipitation type identification and thunderstorm detection.
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1655:) designed for continuous operation which normally remains on at all times, except during maintenance.
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of a vibrating rod. The resonant frequency decreases with increasing accretion (additional mass) of
1408:
Automated airport weather stations use a variety of sophisticated equipment to observe the weather.
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AWOS IV Z/R: all AWOS III P/T parameters, plus freezing rain detection and runway surface condition.
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As of May 22, 2022, the following manufacturers provide FAA-certified, non-federal AWOS systems:
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and are becoming increasingly more prevalent worldwide due to their efficiency and cost-savings.
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precipitation that is not in the form of rain or snow, such as hail, ice pellets and snow grains
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detection via a freezing rain sensor (Note: this configuration used to be called AWOS III PTZ).
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it to point in the direction the wind is coming from and thus providing the wind direction.
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1541:) to determine if and what type of precipitation is falling. The LEDWI sensor measures the
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Optionally (but frequently done), AWOS messages may be transmitted to the FAA for national
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ASOS acquisition control unit, including the three pressure transducers towards the bottom
8:
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Research Moored Array for
African-Asian-Australian Monsoon Analysis and Prediction (RAMA)
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To determine visibility, automated airport weather stations use one of two sensor types:
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Research is on-going to allow the automated stations to detect many of these phenomena.
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is high (i.e., there is a small difference between the temperature and the dew point),
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A majority of older automated airport weather stations are equipped with a mechanical
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Optionally, a computer-generated voice message, available over a telephone dial-up
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1396:) units to AWOS III P/T units. There are no AWSS systems remaining in the US
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Binary
Universal Form for the Representation of meteorological data (BUFR)
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Many automated airport weather stations within the United States use the
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Automated airport weather stations use a temperature/dew point sensor (
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The following AWOS configurations are defined below in terms of what
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pulse for each 0.01-inch (0.25 mm) of precipitation collected.
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2225:"8260.19H - Flight Procedures and Airspace – Document Information"
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This article incorporates text from this source, which is in the
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clouds that are more than twelve thousand feet above ground level
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AWOS III P: all AWOS III parameters, plus precipitation type (
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Prediction and
Research Moored Array in the Atlantic (PIRATA)
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Fog and
Boundary Layer Clouds: Fog Visibility and Forecasting
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1980:
1956:
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1735:(in steps of 0.01 inHg) or whole hectopascals, rounded down.
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Data from a barometric pressure sensor are used to calculate
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Tropospheric
Airborne Meteorological Data Reporting (TAMDAR)
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AWOS systems disseminate weather data in a variety of ways:
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10.1175/1520-0426(2003)020<0820:AMATDD>2.0.CO;2
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Automated airport weather stations use an upward-pointing
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pattern of the precipitation falling through the sensor's
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2172:"SUBJ: Receipt and Dissemination of Weather Observations"
1947:
the automated weather observation. This is often via the
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ASOS all-weather precipitation accumulation gauge (AWPAG)
1711:
1590:
1565:, and various other intermediate forms of precipitation.
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Besides serving aviation needs, ASOS serves as a primary
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DBT Transportation
Services LLC (An ADB SAFEGATE Company)
1118:
service. The message is updated at least once per minute.
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deal primarily with North America and do not represent a
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multiple forms of precipitation falling at the same time
310:
2414:. Springer Science & Business Media. p. 1127.
1598:, humidity is high and visibility is 1/2 mile or less,
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Deep-ocean Assessment and Reporting of Tsunamis (DART)
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observing network in the United States, making up the
2325:"A Multisensor Approach to Detecting Drizzle on ASOS"
2077:"Chapter 7. Safety of Flight. Section 1. Meteorology"
2618:
ASOS LIGHTNING ASSESSMENT - National Weather Service
2250:"Buying, Operating, and Maintaining AWOS – Airports"
2688:Earth-based meteorological observation systems and
164:. Unsourced material may be challenged and removed.
2200:"Surface Weather Observation Stations – ASOS/AWOS"
2147:"Surface Weather Observation Stations – ASOS/AWOS"
1887:automatic lightning detection and reporting system
2913:
1766:into a two-chamber, pivoting container called a
2369:"Freezing Fog: Definition, Causes, and Dangers"
1622:to detect the amount and height of clouds. The
2842:Tropical Atmosphere Ocean project (TAO/TRITON)
2407:
2375:. Archived from the original on 22 August 2016
2013:clouds that are not directly above the station
1813:) was developed. This sensor is essentially a
1719:rely on this value to determine their altitude
1125:via computer. These messages are currently in
2673:
2654:from "NOAA Socioeconomics" website initiative
2329:Journal of Atmospheric and Oceanic Technology
1749:
1613:
1276:AWOS IV R: all AWOS III P/T parameters, plus
1269:AWOS IV Z: all AWOS III P/T parameters, plus
84:The examples and perspective in this article
2937:Meteorological instrumentation and equipment
1872:
1807:all-weather precipitation accumulation gauge
1646:
2401:
1419:
64:Learn how and when to remove these messages
2797:Aircraft Meteorological Data Relay (AMDAR)
2680:
2666:
2460:
2266:
1833:Automated airport weather stations report
1660:platinum wire resistive temperature device
1295:All Weather Inc. (An ADB SAFEGATE Company)
1255:AWOS III T: all AWOS III parameters, plus
2827:Global Sea Level Observing System (GLOSS)
2352:
2141:
2139:
1706:Barometric pressure and altimeter setting
1568:
1533:Automated airport weather stations use a
1325:dew point in degrees Fahrenheit, present
1309:Automated surface observing system (ASOS)
1072:Automated weather observing system (AWOS)
242:Learn how and when to remove this message
224:Learn how and when to remove this message
122:Learn how and when to remove this message
2868:Coastal-Marine Automated Network (C-MAN)
1963:Limitations requiring human augmentation
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2883:Remote Automated Weather Station (RAWS)
2863:Citizen Weather Observer Program (CWOP)
2747:Meteorological Aerodrome Report (METAR)
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1535:light emitting diode weather identifier
1523:Present weather (falling precipitation)
1213:AWOS III: all AWOS II parameters, plus
14:
2914:
2888:Road Weather Information System (RWIS)
2652:Social & Economic Benefits of ASOS
2603:: CS1 maint: archived copy as title (
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2038:Automatic terminal information service
1949:automatic terminal information service
1403:
1384:Automated weather sensor system (AWSS)
335:Summary of Weather Observing Programs
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2010:in-cloud and cloud-to-cloud lightning
1926:Data dissemination is usually via an
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1202:AWOS II: all AWOS I parameters, plus
311:System types within the United States
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1879:National Lightning Detection Network
295:have become part of the backbone of
162:adding citations to reliable sources
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269:suites which are designed to serve
173:"Automated airport weather station"
24:
2641:Automated Surface Observing System
1770:. Precipitation flows through the
1744:tipping bucket precipitation gauge
1315:automated surface observing system
1086:automated weather observing system
325:automated surface observing system
317:automated weather observing system
25:
2948:
2717:Automated airport weather station
2634:
2408:Ismail Gultepe (2 January 2008).
1731:Altimeter setting is reported in
1259:detection (via a cloud-to-ground
45:This article has multiple issues.
2932:Meteorological data and networks
2847:Voluntary observing ship program
2468:"Vaisala CT25K Laser Ceilometer"
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258:An ASOS data collection platform
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2722:Automatic weather station (AWS)
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2337:American Meteorological Society
2087:Federal Aviation Administration
2082:Aeronautical Information Manual
1390:automated weather sensor system
1103:message which is broadcast via
149:needs additional citations for
53:or discuss these issues on the
2323:Wade, Charles G. (June 2003).
2242:
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2111:
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1885:) to detect lightning via the
13:
1:
2822:Global Atmosphere Watch (GAW)
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1368:; another is located at the
1301:Mesotech International, Inc.
1206:and variable visibility (in
361:Precipitation Identification
7:
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2048:Surface weather observation
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1939:(108-137 MHz) at each
1669:ASOS DTS-1 dew point sensor
1518:ASOS present weather sensor
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966:
959:
952:
945:
938:
931:
924:
917:
895:
888:
881:
874:
867:
860:
853:
846:
824:
815:
808:
801:
794:
787:
780:
756:
749:
742:
735:
728:
721:
714:
688:
681:
674:
667:
660:
653:
625:
618:
611:
604:
597:
569:
562:
555:
546:
516:
507:
475:
457:
450:
441:
430:
423:
416:
409:
402:
395:
388:
349:Temperature & Dew Point
98:, discuss the issue on the
10:
2953:
1750:Precipitation accumulation
1614:Cloud coverage and ceiling
1526:
1388:The FAA has converted all
2855:
2817:FluxNet Project (FluxNet)
2784:
2780:
2769:
2707:
2696:
2393:: CS1 maint: unfit URL (
1873:Lightning (thunderstorms)
1849:, freezing fog, freezing
1824:ASOS freezing rain sensor
1756:tipping bucket rain gauge
1647:Temperature and dew point
1440:pulse to travel from one
1415:ASOS ice-free wind sensor
2052:surface weather analysis
1868:ASOS thunderstorm sensor
1642:ASOS HO-1088 thermometer
1420:Wind speed and direction
1398:National Airspace System
1101:computer-generated voice
376:Freezing Rain Occurrence
373:Runway Surface Condition
367:Precipitation Occurrence
364:Thunderstorm / Lightning
263:Airport weather stations
2878:Snow Telemetry (SNOTEL)
2712:Aircraft report (AIREP)
2647:Canada AWOS frequencies
2525:"Corel Office Document"
1475:forward scatter sensors
1304:Optical Scientific Inc.
27:Automated sensor suites
2922:Airport infrastructure
1869:
1825:
1802:
1746:
1702:
1670:
1643:
1610:
1569:Obscurations to vision
1529:Present weather sensor
1519:
1463:
1462:ASOS visibility sensor
1416:
1149:setting (in inches of
1081:
259:
2624:July 6, 2008, at the
2089:. p. Table 7-1-5
2004:depth of new snowfall
1971:shallow or patchy fog
1893:). The NLDN uses 106
1867:
1829:Icing (freezing rain)
1823:
1800:
1741:
1700:
1668:
1641:
1620:laser beam ceilometer
1609:ASOS CT12K ceilometer
1608:
1517:
1461:
1414:
1370:Blue Hill Observatory
1079:
370:Rainfall Accumulation
257:
2927:Aviation meteorology
2752:Pilot report (PIREP)
1910:only in a remark of
1487:particles in the air
158:improve this article
104:create a new article
96:improve this article
2345:2003JAtOT..20..820W
1790:), which sends one
1404:Observing equipment
1163:and wind gusts (in
1143:barometric pressure
336:
279:weather forecasting
1989:volcanic eruptions
1922:Data dissemination
1870:
1839:resonant frequency
1826:
1803:
1747:
1703:
1671:
1644:
1611:
1520:
1464:
1447:ultrasonic sensors
1417:
1339:sea level pressure
1280:surface condition.
1082:
334:
260:
2909:
2908:
2905:
2904:
2901:
2900:
2765:
2764:
2737:Hurricane Hunters
2421:978-3-7643-8419-7
2278:Allweatherinc.com
1912:distant lightning
1733:inches of mercury
1715:altimeter setting
1676:photo transistors
1583:relative humidity
1252:) identification.
1233:accumulation (in
1193:altimeter setting
1080:A commercial AWOS
1069:
1068:
355:Density Altimeter
299:observing in the
252:
251:
244:
234:
233:
226:
208:
132:
131:
124:
106:, as appropriate.
68:
16:(Redirected from
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2782:
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2698:
2697:
2690:weather stations
2682:
2675:
2668:
2659:
2658:
2628:
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2609:
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2594:
2592:
2591:
2582:. Archived from
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2115:
2109:
2103:
2102:
2098:
2096:
2094:
2073:
2007:total snow depth
1653:hygrothermometer
1581:is reported. If
1479:transmissometers
1358:Belvedere Castle
1197:density altitude
1065:
1064:
1048:
1047:
1041:
1040:
1032:
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340:Element Reported
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293:weather stations
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2632:
2631:
2626:Wayback Machine
2620:, Archived at:
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2587:
2580:"Archived copy"
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2447:Meteocentre.com
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2100:
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2034:
1965:
1937:radio frequency
1924:
1875:
1857:, or wet snow.
1831:
1752:
1708:
1649:
1616:
1571:
1531:
1525:
1469:
1422:
1406:
1386:
1311:
1105:radio frequency
1074:
358:Cloud / Ceiling
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1897:nationwide to
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1788:mercury switch
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1527:Main article:
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1350:climatological
1345:accumulation.
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1299:
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1288:observations.
1285:
1284:
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1253:
1248:and sometimes
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1211:
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88:worldwide view
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2586:on 2012-10-19
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2560:News.noaa.gov
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2274:"All Weather"
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2106:public domain
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2873:NEXRAD radar
2757:Weather ship
2716:
2613:
2588:. Retrieved
2584:the original
2574:
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2303:Mesotech.com
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1966:
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1945:broadcasting
1925:
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1914:(LTG DSNT).
1911:
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1904:thunderstorm
1890:
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1742:ASOS heated
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1600:freezing fog
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1257:thunderstorm
1187:(in degrees
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156:Please help
151:verification
148:
118:
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85:
61:
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48:
47:Please help
44:
2308:13 February
2283:13 February
2254:www.faa.gov
2093:16 February
1985:falling ash
1899:triangulate
1784:reed switch
1689:capacitance
1563:ice pellets
1354:first-order
1225:height (in
1181:temperature
283:climatology
2916:Categories
2590:2011-06-26
2565:2013-07-04
2504:Confex.com
2481:30 January
2373:Buzzle.com
2299:"Mesotech"
2259:2019-11-09
2063:References
2019:cloud type
1792:electrical
1782:(either a
1762:, funnels
1633:ceilometer
1467:Visibility
1442:transducer
1438:ultrasonic
1430:cup system
1263:detector).
1204:visibility
1135:parameters
346:Visibility
323:) and the
214:March 2008
184:newspapers
50:improve it
2785:Worldwide
2775:By region
2732:Dropsonde
2477:. Vaisala
2443:"MMmetar"
1994:tornadoes
1928:automated
1847:hoarfrost
1717:. Pilots
1681:heat pump
1426:wind vane
1335:lightning
1261:lightning
1185:dew point
1169:direction
1147:altimeter
842:AWOS-3P/T
352:Altimeter
287:Automated
100:talk page
56:talk page
2622:Archived
2599:cite web
2532:Noaa.gov
2475:Esrl.com
2452:6 August
2427:5 August
2389:cite web
2379:6 August
2032:See also
1974:blowing
1959:format.
1837:via the
1596:freezing
1547:infrared
1167:), wind
1156:AWOS I:
1141:AWOS A:
501:AWOS-A/V
379:Remarks
271:aviation
112:May 2019
94:You may
2742:Mesonet
2702:General
2537:15 June
2509:15 June
2341:Bibcode
2339:: 820.
2229:Faa.gov
2204:Faa.gov
2179:Faa.gov
2151:Faa.gov
2123:Faa.gov
2043:Mesonet
1941:airport
1934:airband
1895:sensors
1851:drizzle
1629:ceiling
1400:(NAS).
1327:weather
1250:drizzle
1189:Celsius
1177:compass
1175:of the
1173:degrees
1151:Mercury
776:AWOS-3T
710:AWOS-3P
297:weather
290:airport
198:scholar
2418:
2234:23 May
2209:23 May
2184:23 May
2156:23 May
2128:23 May
1891:ALDARS
1780:switch
1776:pivots
1772:funnel
1768:bucket
1374:Boston
1278:runway
1235:inches
1109:pilots
1004:Manual
913:AWOS-4
649:AWOS-3
593:AWOS-2
542:AWOS-1
465:AWOS-A
305:Canada
267:sensor
200:
193:
186:
179:
171:
2643:- NWS
2556:(PDF)
2528:(PDF)
2500:(PDF)
2471:(PDF)
2335:(6).
2175:(PDF)
2057:SYNOP
1981:smoke
1957:METAR
1811:AWPAG
1786:or a
1764:water
1624:laser
1539:LEDWI
1510:more.
1372:near
1331:icing
1219:oktas
1208:miles
1165:knots
1161:speed
1127:METAR
1116:modem
205:JSTOR
191:books
102:, or
2802:Argo
2605:link
2539:2017
2511:2017
2483:2015
2454:2016
2429:2016
2416:ISBN
2395:link
2381:2016
2310:2013
2285:2013
2236:2019
2211:2019
2186:2019
2158:2019
2130:2019
2095:2024
2050:and
1976:dust
1883:NLDN
1855:rime
1760:hail
1587:mist
1579:haze
1559:hail
1555:snow
1551:rain
1428:and
1394:AWSS
1341:and
1319:ASOS
1313:The
1246:snow
1242:rain
1227:feet
1217:(in
1195:and
1183:and
1158:wind
1145:and
1090:AWOS
1084:The
384:ASOS
343:Wind
329:ASOS
321:AWOS
303:and
281:and
273:and
177:news
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2349:doi
1931:VHF
1843:ice
1712:QNH
1591:fog
1589:or
1553:or
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