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The The International International AMDAR AMDAR Program Program
Improving Weather Forecasts With AMDAR data are used operationally to support a wide range of meteorological applications and are considered by the World Meteorological Organization to be an essential source of basic upper air information. Since the beginning of flight, weather observations taken from aircraft have made an important contribution towards understanding the current state of the atmosphere so that better weather forecasts can be made. Today, the Aircraft Meteorological Data Relay (AMDAR) system facilitates the fully automated collection and transmission of weather observations from commercial aircraft as well as some military and private aircraft. The AMDAR program has grown rapidly over the past few years with about 2800 aircraft worldwide contributing approximately 250,000 observations per day. AMDAR data are used operationally to support a wide range of meteorological applications and are considered by the World Meteorological Organization to be an essential source of basic upper air information. Onboard sensors, computers and communications systems collect, process, format and transmit the data to ground stations via satellite, VHF or HF radio links. The transition management is performed via ACARS (Aircraft Communications Addressing and Reporting System) or other reporting system. Once on the ground, the data is relayed to the global network of national meteorological services and other authorized users as shown in Figure 1 below. The primary data set from each aircraft participating in the AMDAR program includes position in time and space, wind speed and direction, and ambient temperature. Some aircraft also provide information on moisture, turbulence and ice accretion. They have similar accuracy to radiosonde data and can be used in the same manner. Perhaps one of the most important attributes of the AMDAR data is its cost: a vertical sounding of temperature and wind derived from an aircraft on ascent or descent produces a profile that is typically less than 1% of the cost of a radiosonde sounding. In addition, in some areas of the world, AMDAR soundings provide the only information available on the detailed vertical structure of the atmosphere. AMDAR data from en-route aircraft are a vital component of the global observing network over oceanic areas normally devoid of in-situ observations. They provide high resolution information that help define certain critical atmospheric phenomena that are not well-resolved by satellite data. Work is proceeding to improve temporal and spatial coverage globally and research will enable additional reported elements to be included in the future. Water vapour content in the atmos-
phere is one of the most variable and important energy elements needed for forecasting but it is also the least measured and most poorly defined element. Development of an operational water vapour sensor suitable for aircraft use is due to be completed 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 program. The AMDAR community is developing collaborative arrangments with the aircraft industry with the aim of standardizing the AMDAR on-board software and the water vapour sensor as customer selectable components for all aircraft types.
h Observations From Aircraft Two new alternative AMDAR systems have been developed that offer flexibility and independence from conventional aviation systems and have their own internal and external data processing and monitoring capabilities. TAMDAR (Tropospheric Meteorological Data Reporting) contains a complete sensor package (position, time, wind, temperature, humidity, turbulence, icing) and communications system. AFIRS (Automated Flight Information Reporting System) transmits data from either existing or specially installed sensors to the airline and national meteorological service using another independent communications system. Both systems are suitable for smaller aircraft
Figure 1
that normally do not have ACARS but can also be installed on almost any aircraft. Operational evaluation trials in the USA and Canada indicate that the good quality observations have significant positive impact on NWP and operational forecasting. These systems are ideally suited to areas not normally serviced by the larger ACARS-equipped aircraft.
Data Quality AMDAR data quality is high and suitable for use in all operational meteorological applications that use radiosonde soundings. AMDAR data quality is high and suitable for use in all operational meteorological applications including the climate record that use radiosonde soundings. The quality of observations obtained from each reporting aircraft is routinely monitored by a number of national, regional and global centres and the information is fed back to airlines that benefit directly by using it to help
maintain the high standard of aircraft performance. The NOAA National Centers for Environmental Prediction (NCEP, USA) is the WMO designated lead centre for monitoring aircraft observations. Experience has shown that although there are significant exceptions, the quality of data derived from most large jet transports is high while the quality of similar data derived from many smaller regional and commuter aircraft is often not suitable for meteorological use. Figure 2 shows a typical representation of high quality monthly mean temperature biases during all phases of flight for Canada’s CRJ aircraft while Figure 3 shows the monthly mean temperature bias of all European aircraft that reported in September 2006.
Cost of a vertical AMDAR profile of temperature and wind data is less than 1% of the cost of a radiosonde sounding
Figure 2 - Data quality from CRJ passenger aircraft (bias based on Numerical Model output). Courtesy: Meteorological Service of Canada
Figure 3 - Data Quality of European Aircraft – Courtesy: E-AMDAR Programme (bias based on Numerical Model output)
Data Impact Studies show conclusive positive impact of AMDAR data in weather forecast operations. Real time use of high quality vertical profiles of AMDAR temperature and wind in Australia, the USA, Canada and Hong Kong China has proven to contribute significantly to the improvement in short to medium-term forecasting applications. However, they are particularly useful for now-casting situations where conditions are changing rapidly 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 topographical weather); Thunderstorm genesis, location and severity; Differentiation between rain, snow and freezing rain; Wind-shear location and intensity e.g. dangerous low-level jets (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)
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Studies show conclusive positive impact of AMDAR data on weather forecast operations around the world. NCEP has shown that AMDAR data significantly improved numerical weather prediction (NWP) wind forecasts. For example, 3-hour wind forecast error was reduced by 40% with an overall improvement of 11%. 12-hour wind forecasts of winds improved by 5% (see Figure 5). One of several significant impacts of these improved wind forecasts is better en-route and terminal management of aircraft with subsequent financial savings gained by the airlines. Improved information pertaining to the location and strength of jet stream cores has also led to improved forecasts of major storm events. The WMO Commission for Basic Systems requested the European Center for Medium Range Weather Forecast to study the impact of AMDAR data taken during ascent and descent. The study showed a significant positive impact on the accuracy of medium range NWP. This positive impact allows for improved forecasts by meteorologists supporting a wide range of applications and services to both the public and private sectors.
Figure 4
Data Coverage There are still substantial data sparse areas of the world with very few or no in situ wind and temperature data. The average daily volume of AMDAR data exchanged on the WMO Telecommunications System (GTS) has increased steadily from 3,000 observations since the program’s inception in 1986 to more than 200,000 in 2006 (Figure 10). A further 50,000 observations some of which are derived from proprietary systems, are currently not exchanged on the GTS. There has also been a significant improvement in the global coverage of wind and temperature observation profiles that provide the data most
needed for operational forecasting. Figure 6 is a typical representation of the daily global coverage of en-route and vertical profiles in October 2006 while Figures 7 and 8 show more clearly the global profile sites and the average number of observations collected daily at each site. Of special interest has been the increase over recent years in the number of sites in Africa and East Asia but much more needs to be done. The figures show that there are still substantial data sparse areas of the world where very few in situ profiles are generated and the AMDAR Panel is working with a number of countries and airlines to improve the situation. These areas include Siberia, the Caribbean and South America, the Middle East, Central and South East Asia, South West Pacific and Polar regions.
Figure 8 - Average daily profile observations – Courtesy: Meteorological Service of Canada
Targeted Data AMDAR has the capability to target the collection of upper air observations in most parts of the world. In most parts of the world, AMDAR has the capability of being able to target the collection of upper air observations. This provides a significant opportunity for special collaborative programs to be developed between countries operating long haul flights into countries in data sparse regions that are unable
to develop local programs of their own. For example, the European AMDAR program has commenced providing AMDAR data for the “Agence pour la Sécurite de la Navigation Aérienne en Afrique et à Madagascar” (ASECNA) group of countries in Central and West Africa using long haul aircraft operating from Europe. Optimisation systems are also being developed that will provide targeted data to better define the atmosphere in areas of special meteorological interest. These systems will be used operationally to provide improved leadtime and quality of forecasts of major weather events.
Figure 6 - Typical 24 hour global coverage – Courtesy of NOAA ESRLGSD
Figure 7 - Typical 24-hour profile sites showing large data sparse areas – Courtesy: NOAA ESRL GSD
Figure 9 - AMDAR Panel – United States of America – September 2006
AMDAR “Who We Are” AMDAR is an internationally coordinated program with the core aim of collecting and distributing globally high quality meteorological/environmental data obtained automatically from appropriately equipped aircraft.
AMDAR is an internationally coordinated program with the core aim of collecting and globally distributing high quality meteorological/environmental data obtained automatically from appropriately equipped aircraft. Stakeholders include aircraft operators, national meteorological services, research institutions and other national and international agencies. In recognition of its importance and value as a reliable source of high quality upper air data, AMDAR is being integrated into the World Weather Watch Global Observing System under the World Meteorological Organization. AMDAR will also form an important component of the Earth Observation Summit (Global Earth Observing System of Systems (GEOSS)) that will be supported by WMO and countries committed to providing and using AMDAR data. The AMDAR Panel was formed in 1998 and consists of representatives from WMO Member countries that participate directly in the AMDAR program and provide the funding for its
activities. Panel meetings and workshops are coordinated by the AMDAR Panel and organizations and groups actively involved in the use, development, and participation. Observers currently include international agencies representing airline operators and providers of air traffic control and safety. Other bodies with direct interest include providers of airline communications, aircraft avionics and sensors and research institutes. The AMDAR Panel is the executive manager for the International AMDAR program. At its inauguration, the AMDAR Panel identified 4 high priority projects 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; and 4. Development of Pilot Project for the Middle East. The Panel also has 2 sub-groups that assist its work in 2 highly specialised areas: 1. The Science Sub-group investigates matters relating to the scientific basis and treatment of AMDAR observations; and 2. The Training Sub-group assists Panel members, WMO Regional Associations, the WMO Commission for Basic Systems, and data users with training on AMDAR technology and accessing and using AMDAR data.
What can the AMDAR Panel do for you? The AMDAR Panel is willing and able to assist all countries wishing to gain access and use AMDAR data. An operational AMDAR system requires several major components including: An airline willing to participate in a cooperative agreement; Aircraft with compatible communications, avionics and meteorological sensors; Ground and/or satellite links for the National Meteorological Service (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 program and for interacting with the airline to maintain data quality; A system for real-time control of the volume and location of the data to manage cost.
The AMDAR Panel can help you organise a regional or national program.
The AMDAR Panel can help you organize a regional or national program by: Working with the NMSs and the airlines to evaluate the potential for developing a national AMDAR program; Assisting with technical support and training; Providing technical material and manuals needed to establish a national or regional AMDAR program; Working with the NMS and the airline to create the necessary documents and infrastructure agreements.
A Bright Future for AMDAR AMDAR coverage will continue to improve dramatically as countries with established programs extend coverage and improve efficiencies and many additional countries develop and plan AMDAR programs with active support from the WMO AMDAR Panel. Growth of the AMDAR program has been significant over the past two decades as indicated by Figure 10 showing the average daily number of observations exchanged on the WMO Global Telecommunications System since the commencement of operational AMDAR. AMDAR coverage will continue to improve dramatically as countries with established programs extend coverage and improve efficiencies and many additional countries develop and plan AMDAR programs with active support from the WMO AMDAR Panel.
Utility of Data. The increased spatial and temporal distribution of AMDAR data will make a very important contribution to finer resolution NWP models that are being introduced. It has already been demonstrated in some countries that high resolution AMDAR data improves both broadscale and mesoscale forecasts. It is therefore anticipated that as coverage extends to other regions, this low cost data will similarly provide more accurate forecasts. At the same time, a global optimisation scheme will help ensure the lowest cost possible for the collection of this data.
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Development Plans Finland and several other Western and Eastern European countries in collaboration with the EAMDAR Program, are exploring the possibility of developing new programs to improve coverage as part of the European Composite Observing System (EUCOS). The Russian Federation has indicated it intends to establish a program that will extend into Siberia. The USA, Canada, Australia and Europe are expanding activities in Polar Regions as a contribution for the next International Polar Year 2007-2008. Japan, China and Hong Kong China have initiated new programmes in collaboration with their national and international airlines to improve coverage over East Asia and the North Pacific. This regional group will be assisted by the Republic of Korea as it continues to develop a pilot program. Malaysia, India and Pakistan are proposing to significantly improve coverage over data sparse areas of southern and central Asia. In South America, Chile is well underway towards developing AMDAR capability and Argentina and Brazil intend to develop new programmes. Saudi Arabia has an operational program and the United Arab Emirates, Oman and Egypt have proposed developing new programmes that will expand coverage over the Middle East, North Africa and Asia. South Africa has successfully implemented a regional program that covers southern and East Africa, and Mauritius has commenced planning a program that will provide valuable data over a range of data sparse areas. The ASECNA group of countries in West and Central Africa are working in collaboration with E-AMDAR to develop a substantial programme of targeted observations and Kenya is also contemplating a targeted program. Australia, New Zealand and France are planning to assist development of a regional program in South East Asia and the South West Pacific.
With its projected growth, new technology and low costs, it is clear that AMDAR will become an even more critical component of the strategy to build a complete global observing system for the atmosphere. New Technology and New Information. Work continues to expand the number of additional weather elements to be reported in the next couple of years. A small number of operational aircraft in the USA have begun to report water vapour/humidity, but several countries have plans to install sensors over the next few years. It is anticipated that such information will significantly improve all forecast operations. Specific to aviation, turbulence information is used operationally at some forecasting centres and, together with icing information, new capabilities are being tested and evaluated.
Cost Effectiveness. An AMDAR vertical profile is approximately 1% of the cost of a typical radiosonde profile. With the addition of water vapour information, the potential exists to not only expand the global observational network of soundings, but to use these in place of some existing radiosondes where stratospheric data is not required.
For More Information:
Funded by Deutscher Wetterdienst
In support of the
1.500 - 02/07
www.wmo.int/web/aom/amprog/amprog.html/
