Introduction

The following describe a set of sensor data that AWOS (Automated Weather Observing System) Sensors can produce, and reference data associated with AWOS sensors. 

The "Core concepts" below describes the relationship between the sensors, the airport/runways and measurements produced.

Table of content

Core concepts

ConceptDescription
AirportEverything is related to an airport, identified by name (AirportName) , ICAO code (AirportICAO) and position. All sensors are associated with one airport given by the AirportICAO code.
Runway(s)

An airport has one or more runways. The runways are (of course) static, but the logical (compass oriented) name can change.

RunwaySectionEach runway has 3 RunwaySections (A, B, C) that are static. A runway section is exactly one third of the runway length. The runway sections are named A, B and C. Section naming starts at the lowest runway name (number). 
Sensors

Sensors take measurements of different things, from wind to cloud cover. Each measurement consists of one value of a defined type. If one physical sensor takes measurements of different types it will be considered as if separate sensors were used. Each sensor has a separate (logical) name and can only measure one type of measurements.

Sensors have a placement related to the airport. All sensors have a physical location given by coordinates. Sensors might also have a location associated with for instance a runway section.

Sensor position

Sensors have a static placement, but some can measure things that are non-local (cloud cover).
Sensors can have the following placements:

  • "Close" to the airport
  • Airport
  • Runway section
    • A
    • B
    • C
  • All sensors have a location given by coordinates.
Sensor types

Sensor (measurement) types. A sensor (or a group of sensors at the same location) can take different types measurements, as listed below. 

  • Wind
  • RunwayVisualRange
  • Visibility
  • PresentWeather
  • Temperature
  • Dewpoint
  • Humidity
  • Pressure
  • CloudCover
  • Radiation
Sensor valuesThe sensor, or related software, can measure or calculate a set of values for the different measurement types. A temperature sensor can directly measure the temperature, and can calculate mean temperatures for different periods. Sensor values are of a defined type as given by the element description in the Airport Data Dictionary.
Sensor nameAll sensors have a name that is unique to the airport the sensor is associated with. The names is used to identify the sensor and relevant reference data.


Sensor Reference Data

TermDescription
SensorReferenceDataReference data for one sensor
The ICAO code for the airport this sensor is located at or close to.
Short name for the sensor. Unique for this airport.

The type of measurements this sensor can provide.

Short description of the sensor. 
Short text describing the placement of the sensor. For instance: "200 meters before runway 1".
Of the sensor.
Of the sensor.
Of the sensor
The physical runway, if any, this sensor is associated with. 
The runway section, if any, this sensor is associated with.
When the reference data was last updated.
Time the reference data is valid from.
Time the reference data is valid to.


Sensor Measurement

TermDescription
SensorMeasurementOne measurement, or set of related measurements and calculations from one or more sensors at one airport at one point in time.
AirportICAOThe airport the sensor is related to.
MeasurementTime

Approximate time for the measurements. MeasurementTime is of type TimestampUTC, which means that it can be very precise. For AWOS measurements it is sufficient with seconds. 

RunwayInUse 0..*The runway(s) in use when the measurements were taken. Convenience since the AWOS system should know this.


  • Wind 0..*
Wind measurements from one or more sensors. 
Name of a wind sensor as given in SensorReferenceData. 
The current status of the sensor. 
The wind speed and direction at the MeasurementTime.

    • WindMean2 0..1
Values for the last two minutes.






    • WindMean10 0..1
Values for the last 10 minutes









  • RunwayVisualRange 0..*

Runway visual range (RVR) measurements from one or more sensors. 

Runway Visual Range (RVR) is the range over which the pilot of an aircraft on the center line of a runway can see the runway surface markings or the lights delineating the runway or identifying its center line.

Name of the sensor as given in SensorReferenceData. 

A value of 2001 indicates a range better than 2000 meters, but unspecified.
    • RVRMean10 0..1






  • Visibility 0..*

Visibility measurements from one or more sensors. 

Visibility is a measure of the distance at which an object or light can be clearly discerned. Visibility may vary according to the direction and angle of view, and the height of the observer. Visibility is affected by the presence of fog, cloud, haze and precipitation.

Visibility for aeronautical purposes is the greater of:

  1. the greatest safe distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognised when observed against a bright background;
  2. the greatest distance at which lights in the vicinity of 1000 candelas can be seen and identified against an unlit black background.
Name of the as given in SensorReferenceData. 
The current status of the sensor. 

    • VisibilityMean10 0..1






  • PresentWeather 0..*
Present weather measurements from one or more sensors. See also Wikipedia - Present weather sensor
The purpose of a present weather detector is to detect precipitation and, in some cases, discriminate type and intensity.
Name of the sensor as given in SensorReferenceData. 
The current status of the sensor. 


See OLD - Present Weather Codes, WMO SYNOP 4680, WMO 4678 for WMO4678 codes.

Prevalent weather the last 15 minutes.


Prevalent weather the last 60 minutes.

The measurement here is for the last minute.

The number increases until 999, and then is cleared.
The number increases until 999, and then is cleared.


  • Temperature 0..*
Temperature measurements from one or more sensors. 
Name of the sensor as given in SensorReferenceData. 
The current status of the sensor. 
Temperature degrees Celsius? Mean value last for the minute.
    • TemperatureMean12Day 0..1
Day is 06:00 to 18:00. Yesterdays value until 18:00, then today's values.
Min, max, mean for the "day" period.


    • TemperatureMean12Night 0..1
18:00 - 06:00. Yesterdays value until 06:00, then today's values.
Min, max, mean for the "night" period.


    • TemperatureMean24 0..1
The last 24 hours, sliding window.
Min, max, mean for the last 24 hours.




  • Dewpoint 0..*
Dewpoint measurements from one or more sensors. 
Name of the sensor as given in SensorReferenceData. 




  • Humidity 0..*
Humidity measurements from one or more sensors. 
Name of the sensor as given in SensorReferenceData. 




  • Pressure 0..*
Pressure measurements from one or more sensors. 
Name of the sensor as given in SensorReferenceData. 
The current status of the sensor. 

The pressure set on the subscale of the altimeter so that the instrument indicates its height above the reference elevation being used. The reference elevation will typically be the highest point at the runway. The altimeter will then read '0' at the highest point at the runway.

The pressure set on the subscale of the altimeter so that the instrument indicates its height above sea level. The altimeter will read runway elevation when the aircraft is on the runway.

QFF is the current air pressure at the measuring site (for ex. aerodrome/airport), reduced to the sea level. It is used in the field of meteorology in order to compare the air pressures of different places at different heights.

Actual barometric pressure at the sensor position at the airport.


The change (absolute value) in pressure at the airport as compared to the value 3 hours ago. 

The tendency of the change in the last 3 hours.



  • Cloud 0..*
Cloud measurements from one or more sensors. 
Name of the sensor as given in SensorReferenceData. 
The current status of the sensor. 
    • CloudBase1 0..1

Cloud measurements are of the current situation directly above the sensor. Up to 3 layers of clouds can be measures. 1 represents the lowest of the clouds.

The current value for cloud base 1 (the lowest of up to 3 levels of clouds) measured in Foot above the airport.
Measurement of the thickness, in Foot, of the cloud.
NB! Was PenetrationDepth
    • CloudBase2 0..1



    • CloudBase3 0..1



    • CloudLayer1 0..1
Cloud layers are derived from the cloud measurements above. They are calculated based on 30 minutes of measurements. Up to 3 layers are supported. 1 represents the lowest of the layers.
The current value for cloud layer base 1 (the lowest of up to 3 levels of cloud layers) measured in Foot above the airport.

Indicates how much of the sky that is covered by the cloud layer. Measured in oktas, see Wikipedia: Okta

    • CloudLayer2 0..1



    • CloudLayer3 0..1






  • Radiation 0..*
Radiation measurements from one or more sensors. 
Name of the sensor as given in SensorReferenceData. 
The current status of the sensor. 
    • InstrumentThermistorTemperature
Celsius
    • DownwellingShortwaveFlux

RadiantIntensity   See: https://en.wikipedia.org/wiki/Radiant_intensity   
Unit: Watt per steradian.
XML-type: decimal

    • UpwellingShortwaveFlux
RadiantIntensity
    • DownwellingLongwaveFlux
RadiantIntensity
    • UpwellingLongwaveFlux
RadiantIntensity
    • DownwellingLongwaveFluxCor
RadiantIntensity
    • UpwellingLongwaveFluxCor
RadiantIntensity
    • NetDownwardShortwaveFlux
RadiantIntensity
    • NetDownwardLongwaveFlux
RadiantIntensity
    • NetDownwardRadiativeFlux
RadiantIntensity
    • Albedo
Dimensionless number between 0 and 1, inclusive. XML type: decimal.



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