Aircraft-based Observations Data
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AMDAR Data
AMDAR data is currently transmitted on the WMO Global Telecommunication System (GTS) in both text (FM42, see Manual on Codes, Volume I.1 Alphanumeric Codes) and binary (FM94, see Manual on Codes, Volume I.2 Binary Codes) formats.
A new AMDAR BUFR template has recently been developed and approved as notified in the Amendments to the Manual on Codes by the fast-track, Implemented on 2 May 2012. and WMO recommends that AMDAR programmes follow procedures for the implementation or migration to this format.
The general requirements for transmission of data on the GTS are described in the WMO Manual on Codes, WMO-No. 306.
Specific information and procedures for pre-processing of AMDAR data for transmission of on the WMO Information System and the GTS is available in WMO-No.1200, Guide to Aircraft-Based Observations (see in particular Appendices A and C).
Vertical profiles of AMDAR data are derived as the aircraft is on ascent or descent and en-routed data is derived as the aircraft flies at cruise altitudes of around 35,000 feet (10,500 metres).
From the AMDAR Observing System, the following meteorological parameters are measured or derived:
- Air temperature (static air temperature)
- Wind speed and direction
- Pressure altitude (barometric pressure)
- Turbulence (Eddy Dissipation Rate or Derived Equivalent Vertical Gust)
Additional non-meteorological parameters that can be reported, measured or derived include:
- Latitude position
- Longitude
- Time
- Icing indication (accreting or not accreting)
- Departure and destination airport
- Aircraft roll angle
- Flight number
AMDAR data is processed, compiled and transmitted by the Onboard AMDAR System according to the sampling algorithms and frequencies defined in the AMDAR Onboard Software standards.
Water Vapour Measurement with AMDAR
A water vapour (humidity) measurement from the aircraft platform can also be derived through the deployment and avionics integration of a water vapour sensor. Currently there is a single laser-diode sensor that delivers the required data quality and performance for operational deployment, namely the Water Vapour Sensing System 2nd Generation, WVSS-II, which has been deployed operationally in the USA (around 140 aircraft on UPS and Southwest Airlines) and in the EUMETNET/E-AMDAR Programme (9 Lufthansa aircraft).
More detailed information is available from:
- WMO-No.1200 Guide to Aircraft-Based Observations, section 2.1.2.6
- WMO Guide to Meteorological Instruments and Methods of Observations, WMO-No. 8, Volume III, Chapter 3
Water Vapour Measurement Development
For information about water vapour measurement development under the ABO Programme, see Water Vapour Measurement on this site.
AMDAR Data Quality
For information on AMDAR data quality, see the section on Data Quality in the page on the AMDAR Observing System.
Aircraft-based Observations Data Forum
WMO maintains the Aircraft Observations Data Monitoring email list, which provides WMO Members with information on aircraft-based and AMDAR data quality monitoring. The forum is used for posting of monthly data quality monitoring reports and ad hoc discussion on data quality issues.
The forum is available to AMDAR Focal Points and GTS users and managers of aircraft-based observational data. AMDAR Focal Points area automatically made members of this group.
Subscription
Member experts can apply to be added to the WMO Groups email list by request at the WMO Groups page here. Selecting the group: wmo-aircraft-observations-data-monitoring