History, Data Quality, Utility and Display Aircraft Weather Data History, Data Quality, Utility and Display

Aircraft Weather Data – Outline A short history of aircraft weather data Different sources of data from aircraft Water vapor measurements Resolution and accuracy Data utility Advantages and disadvantages versus other upper air data Display of data Future plans

Aircraft Weather Data – A Short History Aircraft have been used as a source of weather data since the dawn of aviation. In 1904, the United States government began using aircraft to conduct atmospheric research. Weather instruments on a Navy biplane

Aircraft Weather Data – A Short History In 1931, the Weather Bureau began regular aircraft observations at Chicago, Cleveland, Dallas and Omaha, at altitudes reaching 16,000 feet. This program replaced weather observations from "kite stations."

Aircraft Weather Data – A Short History In 1937, the first official Weather Bureau radiosonde sounding was made at Boston, Mass. Weather soundings from aircraft soon ended.

Aircraft Weather Data – A Short History The invention of aircraft data links in the 1970s created renewed interest in using aircraft as weather platforms. The first automated aircraft weather reports were made in 1979. ACARS display units in aircraft cockpit

Aircraft Weather Data – A Short History In the 1980's, the Earth Systems Research Laboratory received permission to use aircraft reports in experimental NWP models. In 1993 ESRL began regular assessment of aircraft data quality. A web based display was developed. Earth Systems Research Lab

Aircraft Weather Data – A Short History March 20, 1996 the airlines agreed to allow direct access to their data by NWS WFO meteorologists. Other users now include the FAA, DOD, and universities. NWS office in Green Bay, Wisconsin

Aircraft Weather Data – Different Sources You may have heard aircraft data referred to as ACARS, MDCRS, AMDAR or TAMDAR. ACARS (Aircraft Communications, Addressing, and Reporting System) is the name of a datalink service provided by Aeronautical Radio Inc. that sends information between aircraft and ground stations. MDCRS (Meteorological Data, Collection and Reporting System) is the weather portion of the ACARS data stream. Aircraft Meteorological DAta Report (AMDAR) is the preferred term by the WMO and NWS. TAMDAR (Tropospheric AMDAR) is provided by a private company, AIRDAT, using a regional air carrier.

Aircraft Weather Data – Different Sources Eight U.S. Airlines share AMDAR American Delta FEDEX Mesaba Northwest Southwest United UPS The airlines share the cost of down linking the data with the NWS and FAA

Aircraft Weather Data – Different Sources 14 Countries now share AMDAR from 2,300 aircraft Australia, New Zealand, China, Hong Kong China, Saudi Arabia, South Africa, United States, Canada, Netherlands, United Kingdom, France, Sweden, Hungary, Germany 5 Countries developing AMDAR systems Chile, Finland, Argentina, Republic of Korea, and United Arab Emirates

Aircraft Weather Data – Different Sources The number of observations has increased greatly, and is now over a quarter million per day from around the world!

Aircraft Weather Data – Measured Quantities Nearly all participating AMDAR aircraft report temperature and wind data. Temperature is determined by the Total Air Temperature sensor, while ground relative winds are computed using an Inertial Navigation System or GPS. As of 2006, fewer than 10 percent of AMDAR aircraft measured water vapor, turbulence and icing.

Aircraft Weather Data – Water Vapor Measuring water vapor in the upper atmosphere is a difficult task for any sensor. NWS radiosondes use thin film capacitors to measure relative humidity. The sensors are relatively inexpensive, but sometimes are prone to errors at very high and very low relative humidity.

Aircraft Weather Data – Water Vapor Studies in the early 1990s showed that relative humidity measurements from commercial aircraft were feasible. A sensor called the “Water Vapor Sensing System” (WVSS) using a thin film capacitor was installed on six UPS aircraft between 1997 and 1999. Water Vapor Sensing System Unit

Aircraft Weather Data – Water Vapor While the WVSS data compared favorably with radiosondes, the sensors needed to be replaced too frequently to be used on commercial aircraft.

Aircraft Weather Data – Water Vapor A new sensor (WVSS-II) employs a diode laser to measure water vapor mixing ratio. WVSS-II was installed on 25 UPS aircraft between 2004 and 2005. WVSS-II laser diode shown next to a penny, for size comparison purposes.

Aircraft Weather Data – Water Vapor Field studies were conducted at the Louisville airport (June 2005, November 2006) to compare WVSS-II with precision radiosondes. A mobile sounding unit from the University of Wisconsin launched radiosondes every three hours during the evening and overnight hours. This was supplemented by interferometer data. WVSS-II and radiosonde data within an hour and 50km of each other were compared. Mixing ratio was measured by WVSS-II and relative humidity by the radiosonde.

Aircraft Weather Data – Water Vapor Results from the WVSS-II and radiosonde comparison showed an average relative humidity bias near zero in the lowest 200hPa and about 5% above. Standard deviations are about 5% below 800hPa and 10% above. The accuracy satisfies WMO requirements for regional forecast applications.

Aircraft Weather Data – Resolution And Accuracy Much as ASOS, AWOS, DOT and mesonet observations have differences in reporting frequency, accuracy and reliability, so too do reports from aircraft. Most AMDAR from foreign airlines conform to a WMO reporting standard called ARINC 620. U.S. AMDAR observations generally do not.

Aircraft Weather Data – Resolution And Accuracy ARINC 620 standard provides a data point every 300 feet up to around 850 hPa, then every 1000 feet to cruise altitude. Most U.S. AMDAR report data at set 1,000-2,000 foot intervals through ascent and descent. The NWS and WMO are urging U.S. airlines to adopt ARINC 620 standard.

Aircraft Weather Data – Resolution And Accuracy Many studies have been conducted to compare AMDAR to radiosondes, profilers and other upper air data. They generally show that AMDAR temperatures and winds are slightly superior to those from radiosondes.

Aircraft Weather Data – Resolution and Accuracy A 2001 study by Erik Andersson, Carla Cardinali and Antonio Garcia-Mendez of the ECMWF showed the addition of AMDAR resulted in significant model forecast improvements, all the way out to 7 days.

Aircraft Weather Data – Resolution and Accuracy

Aircraft Weather Data – Resolution and Accuracy A study conducted by Ralph Petersen, Geoff Manikin and Dennis Keyser showed that AMDAR contributes significantly to the RUC at all run times. In fact, the RUC provides little value at asynoptic times without AMDAR – the RUC accuracy declined 20% in the days following September 11, 2001 when air traffic was grounded.

Aircraft Weather Data – Forecast Applications AMDAR data have proven extremely useful in a wide variety of forecast situations, including: Aviation Low level wind shear Ceilings and visibilities Icing and turbulence Winter Storms Precipitation type Lake effect snow Thunderstorms Convective initiation Calculation of stability indices Fire Weather Mixing heights Haines indices Relative humidity forecasts Marine Forecasts Small craft and Gale Warnings Hazardous Materials Support AMDAR can be used to support HAZMAT teams Can be input into local dispersion models

Advantages and Disadvantages Like any system, AMDAR has advantages and disadvantages.

Disadvantages Volume of data may be reduced during large storms. Most aircraft do not measure water vapor. AMDAR soundings usually end at 500hPa for regional aircraft, and 250hPa for most others.

Advantages Soundings are not limited to 00UTC and 12UTC. This is important especially during convective season. Many airports have 10 or more soundings per day (Some large airports have over 100). AMDAR does not have limiting angles problems like radiosondes. Inexpensive (AMDAR sounding less than $1 vs. $200 for radiosonde)

Aircraft Weather Data – Display Options AMDAR are available in real-time to the NWS, FAA, and DOD via the ESRL aircraft data web at http://amdar.noaa.gov. AMDAR may also be displayed on AWIPS, via the volume browser.

ESRL Aircraft Data http://amdar.noaa.gov has links to AMDAR data, FAQs, research papers, training materials and more. Web site has archive of about 3 years of data, allowing for easy retrieval for case studies. Data can be found at http://amdar.noaa.gov/java.

AMDAR Display Options– Web ESRL web page should allow access to data at all NOAA installations. Contact Bill Moninger at ESRL regarding access issues. (303) 497-6435 William.R.Moninger@noaa.gov Data may not be redistributed in real time.

Web Display Resources Additional training on the use of the web page can be found at http://amdar.noaa.gov/videos/.

Future Plans - NWS Support existing AMDAR data network Expand number of participating regional airlines Reduce redundant AMDAR soundings at hubs (optimization) Increase number of water vapor sensors Let contract for management of water vapor sensing program this year Deploy 110 units annually through 2010 Reach ~1600 units deployed by 2020

Future Plans - WMO Support expansion of AMDAR network - Assist emerging national AMDAR programs Provide recommendations for data formats Provide training and outreach

References – History of Aircraft Data Hughes, P., 1970: A Century of Weather Service, Gordon and Breech, 212 p.p. Hughes and Gedzelman, 1995: The New Meteorology. Weatherwise. 48, 26-36 Moninger, W. R., R. D. Mamrosh, and P. M. Pauley: Automated Meteorological Reports from Commercial Aircraft. Bull. Amer. Meteor. Soc., 84, 203-216

References – Different Sources Cunning, J., 2000: Commercial Aircraft Provided Weather Data, Preprints, Fourth Symposium on Integrated Observing Systems, Long Beach, CA, Amer. Meteor. Soc., 45-48 Moninger, W. R. and P. A. Miller, 1994: ACARS Quality Control, Monitoring, and Correction. 10th Conference on Numerical Weather Prediction, Portland, OR, Amer. Meteor. Soc. 1-3

References – Resolution and Accuracy Benjamin, S.G., B.E. Schwartz, and R.E. Cole, 1999: Accuracy of ACARS wind and temperature observations determined by collocation. Wea. Forecasting, 14, 1032-1038. Jamison, Brian and William R. Moninger, 2002: An Analysis of the Temporal and Spatial Distribution of ACARS data in support of the TAMDAR program. 10th Conf. on Aviation, Range, and Aerospace Meteorology, Portland, OR, Amer. Meteor. Soc. Lord, R.J., W.P. Menzel, and L.E. Pecht, 1984: ACARS wind measurements: An inter-comparison with radiosonde, cloud motion, and VAS thermally derived winds. J. Atmos. Oceanic Technol., 1, 131-137. Morone, L.L., 1986: The observational error of automated wind reports from aircraft. Bull. Amer. Meteor. Soc., 67, 177-185. Schwartz, B. E., and S. C. Benjamin, 1995: A Comparison of Temperature and Wind Measurements from ACARS-Equipped Aircraft and Rawinsondes. Wea. Forecasting, 10, 528-544.

Supplemental Slides

Aircraft Weather Data – Resolution And Accuracy

Aircraft Weather Data – Resolution and Accuracy

Aircraft Weather Data – Resolution and Accuracy

Aircraft Weather Data – Resolution and Accuracy