Aircraft-Based Observations programme
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Introduction
Aircraft-based observations have made a significant contribution to upper-air monitoring of the atmosphere for many decades. Initially, this contribution was limited to PIlot REPorts (PIREP), consisting of little more than radio communications from pilots back to the ground regarding weather phenomena and conditions encountered during flight. Later, with the advent of more sophisticated onboard equipment and avionics, such reports would be standardised and eventually automated into AIRcraft REPorts (AIREPS) of measured weather variables including air temperature and wind speed and direction, provided with positional information. These reports are still made, received and utilised within meteorological applications, through reporting regulations and data exchange arrangements with the International Civil Aviation Organization (ICAO).
In recent decades, the use of the aircraft platform for the automated collection of meteorological data has been considerably enhanced and expanded so as to provide more accurate, more timely and, most importantly a much greater volume of upper-air data in support of data users and meteorological applications, including support for weather-related forecasting and monitoring for the Aviation Industry. The chief source of aircraft-based observations supporting the Global Observing Systemand the World Weather Watch Programme are derived from the Aircraft Meteorological DAta Relay (AMDAR) system.
Detailed information and guidance for WMO members on aircraft-based observations is available in WMO-No. 1200, Guide to Aircraft-Based Observations.
AMDAR Observations
Aircraft Meteorological DAta Relay (AMDAR) Observations are obtained from the WMO global AMDAR observing system, which is comprised of those aircraft-based observing systems, which derive meteorological data from an aircraft platform according to WMO standards and specifications and make it available on the WMO Global Telecommunications System (GTS). The WMO AMDAR observing systems is comprised of the national and regional Member AMDAR systems, which are implemented and operated in collaboration with AMDAR partner commercial airlines.
The onboard component of the AMDAR system is essentially an avionics software application that utilises existing onboard sensors and navigation, communications and computer systems to automatically collect and compile meteorological data and then transmit it to the ground in real-time as the aircraft flies.
The WMO global AMDAR system now produces over 700,000 high-quality observations per day of air temperature and wind speed and direction, together with the required positional and temporal information and with an increasing number of humidity and turbulence measurements being made.
WMO urges Members to continue to develop and expand the AMDAR observing system in line with the Actions of CBS Implementation Plan for the Evolution of the Global Observing System.
From 1998 until 2012, the development and implementation of the AMDAR system was the responsibility of the WMO AMDAR Panel, however, at its 15th Session, the AMDAR Panel formally handed over this responsibility to WMO and its Technical Commissions.
Other Aircraft-based Observations
While the WMO AMDAR Observing System is the chief source of aircraft-based observations on the GTS, other aircraft-based observations are derived from several sources including:
- Under regulations and cooperative arrangements with ICAO, data from PIlot REPorts (PIREP), AIRcraft REPorts (AIREP) and Automatic Dependent Surveillance Contract (ADS-C) is available on the GTS for utilisation by data users.
- AMDAR-like data can also be derived from commercially operated observing systems, such as the FLYHT TAMDAR system, and may be available on the GTS, depending on the arrangements between the contracting NMHS and the vendor for the purchase of the data.
More information on these aircraft-based observations data sources is available from WMO-No. 1200, Guide to Aircraft-Based Observations and from this website under the Data area.
WMO Teams on Aircraft-based Observations
Under the CBS and CIMO Technical Commissions, work teams have been established in order to continue the previous work of the AMDAR Panel in maintaining and developing the aircraft-based observations programme and the AMDAR Observing System, supported by the AMDAR Trust Fund and WMO Members.