About the AMDAR Observing System

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Introductory Information About the AMDAR Observing System

The global Aircraft Meteorological Data Relay (AMDAR) programme was initiated by the World Meteorological Organization (WMO) and its Members, in cooperation with aviation partners and has led to the development of the AMDAR observing system. The AMDAR observing system is a sub-system of the WMO Integrated Global Observing System and the Global Observing System, which is defined and maintained under the WMO World Weather Watch Programme.

The AMDAR system utilises predominantly existing aircraft onboard sensors, computers and communications systems to collect, process, format and transmit meteorological data to ground stations via satellite or radio links. Once on the ground, the data is relayed to National Meteorological and Hydrological Services, where it is processed, quality controlled and transmitted on the WMO Information System (WIS).

The WMO global AMDAR system now (May 2017) 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.

The data collected is used for a range of meteorological applications, including, public weather forecasting, climate monitoring and prediction, early warning systems for weather hazards and, importantly, weather monitoring and prediction in support of the aviation industry.

The global AMDAR observing system is comprised of the operational AMDAR observing systems maintained by National & Regional AMDAR Programmes in collaboration with their partner airlines.

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.

WMO maintains the international regulatory material and standards for operation of the AMDAR observing system and, through it's Technical Commissions, oversees the maintenance and development of the AMDAR observing system and the work program on aircraft-based observations through the coordination of Technical Commission expert teams.

WMO urges Members to continue to develop and expand the AMDAR observing system in line with the Actions of the Commission for Basic Systems (CBS) Implementation Plan for the Evolution of the Global Observing System.

Resource material related to national and regional AMDAR programme development can be found in the AMDAR Resources/AMDAR Programme Development area.

AMDAR History

AMDAR was proposed for the First Global Atmospheric Research Programme (GARP) Global Experiment (FGGE) in the 1970s. Two systems were developed, one using communications facilities available on the meteorological geo-synchronous satellites - the geostationary operational environmental satellite (GOES), Meteosat and geostationary meteorological satellite (GMS); and one using a standard aircraft VHF communication system (ACARS) developed in the United States and rapidly gaining worldwide acceptance.

The satellite system, Aircraft to Satellite Data Relay (ASDAR) was sponsored by a consortium of WMO Members and was developed into an operational system by 1991. ACARS-based systems require no additional specialized equipment to be fitted to the aircraft, whereas ASDAR uses a dedicated data processor and satellite transmitter. Experience with both systems has led to the conclusion that ACARS-based AMDAR systems are preferred, based on ease of implementation, worldwide applicability and overall cost. ASDAR operations reached a peak in the late 1990s but no further ASDAR developments are envisaged now.

Several new AMDAR systems are being developed using alternative methods for sensing and communications. New purpose-designed sensor modules are being developed and communications techniques are being built based on non-ACARS VHF communications and low Earth orbit (LEO) satellites. Global cooperation on AMDAR is facilitated by the WMO AMDAR Panel established in 1998 by a number of WMO Members operating or intending to operate AMDAR programmes.

Following on from the successful ASDAR programme, the AMDAR Panel was formally established in March 1998. At the inaugural meeting the goal, terms of reference, membership and operating procedures were agreed upon. The goal of the AMDAR Panel is to enhance the upper-air component of the Composite Observing System of the WWW. This is to be achieved through cooperation among Members in the acquisition, exchange and quality control of meteorological observations from aircraft using automated reporting systems. The Panel recognized a fundamental principle of WMO to broaden and enhance the free and unrestricted international exchange of data, and noted the increasing availability of aircraft platforms with suitable sensors, avionics and communications systems.

The Panel was established to take advantage of the opportunity to use these new cost-effective global data sources to better respond to the needs of WMO and WMO-sponsored programmes such as the WWW, World Climate Research Programme (WCRP), Global Climate Observing System (GCOS) and Global Ocean Observing System (GOOS), and to bring potential benefits to end-users in aviation and other communities. The Panel is considered necessary to ensure a coordinated approach to the development of AMDAR as an operational global programme with particular benefits in data-sparse areas of the world. To help facilitate the work of the Panel, a Technical Coordinator (TC) was appointed in April 1999. An AMDAR Trust Fund was established to assist with the work of the Panel and is reliant on voluntary contributions from Panel members.