The InternationalAMDAR ProgramThe InternationalAMDAR ProgramThe InternationalAMDAR Program

Aircraft Meteorological DAta RelayAircraft Meteorological DAta RelayAircraft Meteorological DAta Relay

Since the beginning of flight, weather observations taken fromaircraft have made an important contribution towards under-standing the current state of the atmosphere so that betterweather forecasts can be made. Today, the Aircraft Meteoro-logical Data Relay (AMDAR) system facilitates the fully auto-mated collection and transmission of weather observationsfrom commercial aircraft as well as some military and privateaircraft. The AMDAR program has grown rapidly over the pastfew years with about 2800 aircraft worldwide contributingapproximately 250,000 observations per day. AMDAR data areused operationally to support a wide range of meteorologicalapplications and are considered by the World MeteorologicalOrganization to be an essential source of basic upper airinformation.

Onboard sensors, computers and communications systemscollect, process, format and transmit the data to ground stationsvia satellite, VHF or HF radio links. The transition managementis performed via ACARS (Aircraft Communications Addressingand Reporting System) or other reporting system. Once on theground, the data is relayed to the global network of nationalmeteorological services and other authorized users as shownin Figure 1 below.

The primary data set from each aircraft participating in theAMDAR program includes position in time and space, windspeed and direction, and ambient temperature. Some aircraftalso provide information on moisture, turbulence and iceaccretion. They have similar accuracy to radiosonde data andcan be used in the same manner. Perhaps one of the mostimportant attributes of the AMDAR data is its cost: a verticalsounding of temperature and wind derived from an aircraft onascent or descent produces a profile that is typically lessthan 1% of the cost of a radiosonde sounding. In addition, insome areas of the world, AMDAR soundings provide the onlyinformation available on the detailed vertical structure of theatmosphere. AMDAR data from en-route aircraft are a vitalcomponent of the global observing network over oceanic areasnormally devoid of in-situ observations. They provide highresolution information that help define certain critical atmo-spheric phenomena that are not well-resolved by satellite data.

Work is proceeding to improve temporal and spatial coverageglobally and research will enable additional reported elementsto be included in the future. Water vapour content in the atmos-

phere is one of the most variable and important energy elementsneeded for forecasting but it is also the least measured andmost poorly defined element. Development of an operationalwater vapour sensor suitable for aircraft use is due to be com-pleted by 2007. Following evaluation trials in the USA and Europe,sensors will be installed on aircraft in the USA, Europe, Australia,New Zealand and South Africa as part of a collaborative pro-gram. The AMDAR community is developing collaborativearrangments with the aircraft industry with the aim of standard-izing the AMDAR on-board software and the water vapour sen-sor as customer selectable components for all aircraft types.

Improving Weather Forecasts With

AMDAR data are used operationallyto support a wide range of meteoro-logical applications and are consi-dered by the World MeteorologicalOrganization to be an essential sour-ce of basic upper air information.

Two new alternative AMDAR systems have been developed thatoffer flexibility and independence from conventional aviationsystems and have their own internal and external data pro-cessing and monitoring capabilities. TAMDAR (TroposphericMeteorological Data Reporting) contains a complete sensorpackage (position, time, wind, temperature, humidity, turbu-lence, icing) and communications system. AFIRS (AutomatedFlight Information Reporting System) transmits data from eitherexisting or specially installed sensors to the airline and nationalmeteorological service using another independent communi-cations system. Both systems are suitable for smaller aircraft

that normally do not have ACARS but can also be installed onalmost any aircraft. Operational evaluation trials in the USAand Canada indicate that the good quality observations havesignificant positive impact on NWP and operational forecasting.These systems are ideally suited to areas not normally servicedby the larger ACARS-equipped aircraft.

h Observations From Aircraft

Figure 1

AMDAR data quality is high and suitable for use in all operationalmeteorological applications including the climate record thatuse radiosonde soundings. The quality of observations obtainedfrom each reporting aircraft is routinely monitored by a numberof national, regional and global centres and the information isfed back to airlines that benefit directly by using it to help

maintain the high standard of aircraft performance. The NOAANational Centers for Environmental Prediction (NCEP, USA) isthe WMO designated lead centre for monitoring aircraftobservations. Experience has shown that although there aresignificant exceptions, the quality of data derived from mostlarge jet transports is high while the quality of similar dataderived from many smaller regional and commuter aircraft isoften not suitable for meteorological use. Figure 2 shows atypical representation of high quality monthly mean temperaturebiases during all phases of flight for Canada’s CRJ aircraft whileFigure 3 shows the monthly mean temperature bias of allEuropean aircraft that reported in September 2006.

Data Quality

AMDAR data quality is high andsuitable for use in all operationalmeteorological applications that use radiosonde soundings.

Cost of a verticalAMDAR profile oftemperature andwind data is lessthan 1% of the cost of a radiosonde sounding

Figure 2 - Data quality from CRJpassenger aircraft (bias based onNumerical Model output). Courtesy:Meteorological Service of Canada

Figure 3 - Data Quality of EuropeanAircraft – Courtesy: E-AMDARProgramme (bias based onNumerical Model output)

Studies show conclusive positive impact of AMDAR data inweather forecast operations. Real time use of high qualityvertical profiles of AMDAR temperature and wind in Australia,the USA, Canada and Hong Kong China has proven to contributesignificantly to the improvement in short to medium-termforecasting applications. However, they are particularly usefulfor now-casting situations where conditions are changingrapidly and are therefore of special use to the aviation industry.Such applications include:

Surface and upper air forecasts of wind and temperature(including severe wind, onset of sea breeze and local topo-graphical weather); Thunderstorm genesis, location and severity;Differentiation between rain, snow and freezing rain;Wind-shear location and intensity e.g. dangerous low-leveljets (Figure 4). Low cloud formation, location and duration;Fog formation, location and duration;Turbulence location and intensity;Jetstream location and intensity;Environmental control information (trapping inversions etc)

NCEP has shown that AMDAR data significantly improvednumerical weather prediction (NWP) wind forecasts. Forexample, 3-hour wind forecast error was reduced by 40% withan overall improvement of 11%. 12-hour wind forecasts ofwinds improved by 5% (see Figure 5). One of several significantimpacts of these improved wind forecasts is better en-routeand terminal management of aircraft with subsequent financialsavings gained by the airlines. Improved information pertainingto the location and strength of jet stream cores has also ledto improved forecasts of major storm events.

The WMO Commission for Basic Systems requested the Euro-pean Center for Medium Range Weather Forecast to study theimpact of AMDAR data taken during ascent and descent. Thestudy showed a significant positive impact on the accuracy ofmedium range NWP. This positive impact allows for improvedforecasts by meteorologists supporting a wide range of appli-cations and services to both the public and private sectors.

Data Impact

Studies show conclusive positiveimpact of AMDAR data on weatherforecast operations around the world.

Figure 5

Figure 4

The average daily volume of AMDAR data exchanged on theWMO Telecommunications System (GTS) has increased steadilyfrom 3,000 observations since the program’s inception in 1986 tomore than 200,000 in 2006 (Figure 10). A further 50,000 obser-vations some of which are derived from proprietary systems,are currently not exchanged on the GTS. There has also beena significant improvement in the global coverage of wind andtemperature observation profiles that provide the data most

needed for operational forecasting. Figure 6 is a typicalrepresentation of the daily global coverage of en-route andvertical profiles in October 2006 while Figures 7 and 8 showmore clearly the global profile sites and the average numberof observations collected daily at each site. Of special interesthas been the increase over recent years in the number of sitesin Africa and East Asia but much more needs to be done. Thefigures show that there are still substantial data sparse areasof the world where very few in situ profiles are generated andthe AMDAR Panel is working with a number of countries andairlines to improve the situation. These areas include Siberia,the Caribbean and South America, the Middle East, Centraland South East Asia, South West Pacific and Polar regions.

Data Coverage

There are still substantial data spar-se areas of the world with very fewor no in situ wind and temperaturedata.

Figure 8 - Average daily profile observations – Courtesy:Meteorological Service of Canada

Figure 6 - Typical 24 hour global coverage – Courtesy of NOAA ESRLGSD

In most parts of the world, AMDAR has the capability of beingable to target the collection of upper air observations. Thisprovides a significant opportunity for special collaborativeprograms to be developed between countries operating longhaul flights into countries in data sparse regions that are unable

to develop local programs of their own. For example, theEuropean AMDAR program has commenced providing AMDARdata for the “Agence pour la Sécurite de la NavigationAérienne en Afrique et à Madagascar” (ASECNA) group ofcountries in Central and West Africa using long haul aircraftoperating from Europe. Optimisation systems are also beingdeveloped that will provide targeted data to better define theatmosphere in areas of special meteorological interest. Thesesystems will be used operationally to provide improved lead-time and quality of forecasts of major weather events.

Targeted Data

AMDAR has the capability to targetthe collection of upper air observati-ons in most parts of the world.

Figure 7 - Typical 24-hour profile sites showing largedata sparse areas – Courtesy:NOAA ESRL GSD

AMDAR is an internationally coordinated program with the coreaim of collecting and globally distributing high quality meteorolo-gical/environmental data obtained automatically from appro-priately equipped aircraft. Stakeholders include aircraft ope-rators, national meteorological services, research institutionsand other national and international agencies. In recognitionof its importance and value as a reliable source of high qualityupper air data, AMDAR is being integrated into the WorldWeather Watch Global Observing System under the World Mete-orological Organization. AMDAR will also form an importantcomponent of the Earth Observation Summit (Global EarthObserving System of Systems (GEOSS)) that will be supported byWMO and countries committed to providing and using AMDARdata.

The AMDAR Panel was formed in 1998 and consists of repre-sentatives from WMO Member countries that participatedirectly in the AMDAR program and provide the funding for its

activities. Panel meetings and workshops are coordinated bythe AMDAR Panel and organizations and groups actively involvedin the use, development, and participation. Observers currentlyinclude international agencies representing airline operatorsand providers of air traffic control and safety. Other bodieswith direct interest include providers of airline communications,aircraft avionics and sensors and research institutes. TheAMDAR Panel is the executive manager for the InternationalAMDAR program.

At its inauguration, the AMDAR Panel identified 4 high priorityprojects to help focus activities:1. Coordination of National and Regional Programs;2. Improvement in Data Exchange and Quality Control;3. Development of Pilot Project for Southern Africa; and4. Development of Pilot Project for the Middle East.

The Panel also has 2 sub-groups that assist its work in 2 highlyspecialised areas:1. The Science Sub-group investigates matters relating to the

scientific basis and treatment of AMDAR observations; and2. The Training Sub-group assists Panel members, WMO

Regional Associations, the WMO Commission for BasicSystems, and data users with training on AMDAR technologyand accessing and using AMDAR data.

AMDAR “Who We Are”

AMDAR is an internationally coordinatedprogram with the core aim of collectingand distributing globally high quality mete-orological/environmental data obtainedautomatically from appropriately equippedaircraft.

Figure 9 - AMDAR Panel – United States of America – September 2006

The AMDAR Panel is willing and able to assist all countrieswishing to gain access and use AMDAR data.

An operational AMDAR system requires several major com-ponents including:

An airline willing to participate in a cooperative agreement;Aircraft with compatible communications, avionics andmeteorological sensors;Ground and/or satellite links for the National MeteorologicalService (NMS) to obtain the data from the airline;Ground-based processing system and connection to the GTS;A system for monitoring the performance of the programand for interacting with the airline to maintain data quality;A system for real-time control of the volume and location ofthe data to manage cost.

The AMDAR Panel can help you organize a regional ornational program by:

Working with the NMSs and the airlines to evaluate thepotential for developing a national AMDAR program;Assisting with technical support and training;Providing technical material and manuals needed to establisha national or regional AMDAR program;Working with the NMS and the airline to create the neces-sary documents and infrastructure agreements.

What can the AMDAR Panel do for you?

The AMDAR Panel can help you organisea regional or national program.

Growth of the AMDAR program has been significant over thepast two decades as indicated by Figure 10 showing the ave-rage daily number of observations exchanged on the WMOGlobal Telecommunications System since the commencementof operational AMDAR. AMDAR coverage will continue toimprove dramatically as countries with established programsextend coverage and improve efficiencies and many additionalcountries develop and plan AMDAR programs with activesupport from the WMO AMDAR Panel.

Utility of Data. The increased spatial and temporal distributionof AMDAR data will make a very important contribution to finerresolution NWP models that are being introduced. It has alreadybeen demonstrated in some countries that high resolutionAMDAR data improves both broadscale and mesoscale fore-casts. It is therefore anticipated that as coverage extends toother regions, this low cost data will similarly provide moreaccurate forecasts. At the same time, a global optimisationscheme will help ensure the lowest cost possible for the col-lection of this data.

A Bright Future for AMDAR

AMDAR coverage will continue to improve dramati-cally as countries with established programs extendcoverage and improve efficiencies and many addi-tional countries develop and plan AMDAR programswith active support from the WMO AMDAR Panel.

Development PlansFinland and several other Western and EasternEuropean countries in collaboration with the E-AMDAR Program, are exploring the possibility ofdeveloping new programs to improve coverage as partof the European Composite Observing System (EUCOS).

The Russian Federation has indicated it intends to establisha program that will extend into Siberia.

The USA, Canada, Australia and Europe are expanding activities in PolarRegions as a contribution for the next International Polar Year 2007-2008.

Japan, China and Hong Kong China have initiated new programmes in collaboration withtheir national and international airlines to improve coverage over East Asia and theNorth Pacific. This regional group will be assisted by the Republic of Korea as it continu-es to develop a pilot program.

Malaysia, India and Pakistan are proposing to significantly improve coverage over datasparse areas of southern and central Asia.

In South America, Chile is well underway towards developing AMDAR capability andArgentina and Brazil intend to develop new programmes.

Saudi Arabia has an operational program and the United Arab Emirates, Oman and Egypt haveproposed developing new programmes that will expand coverage over the Middle East, NorthAfrica and Asia.

South Africa has successfully implemented a regional program that covers southern and EastAfrica, and Mauritius has commenced planning a program that will provide valuable data overa range of data sparse areas.

The ASECNA group of countries in West and Central Africa are working in collaboration withE-AMDAR to develop a substantial programme of targeted observations and Kenya is alsocontemplating a targeted program.

Australia, New Zealand and France are planning to assist development of a regional program inSouth East Asia and the South West Pacific.

Figure 10

New Technology and New Information. Work continues toexpand the number of additional weather elements to bereported in the next couple of years. A small number of ope-rational aircraft in the USA have begun to report watervapour/humidity, but several countries have plans to installsensors over the next few years. It is anticipated that suchinformation will significantly improve all forecast operations.Specific to aviation, turbulence information is used operatio-nally at some forecasting centres and, together with icinginformation, new capabilities are being tested and evaluated.

Cost Effectiveness. An AMDAR vertical profile is approxima-tely 1% of the cost of a typical radiosonde profile. With theaddition of water vapour information, the potential exists tonot only expand the global observational network of soun-dings, but to use these in place of some existing radiosondeswhere stratospheric data is not required.

With its projected growth, new technology and lowcosts, it is clear that AMDAR will become an evenmore critical component of the strategy to build acomplete global observing system for the atmosphere.

Deutscher WetterdienstFunded by In support of the 1.50

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