Aircraft Weather Data

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Aircraft Weather Data

• History, Data Quality, Utility and Display

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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

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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
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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."

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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.

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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
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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
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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
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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.

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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
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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

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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!

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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.

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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.

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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
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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.
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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.
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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.
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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.
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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.

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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.

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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.

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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.

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Aircraft Weather Data Resolution and Accuracy
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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.

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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

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Advantages and Disadvantages

• Like any system, AMDAR has advantages and
  disadvantages.

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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.

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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)

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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.

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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.

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AMDAR Display Options Web

• ESRL web page should allow access to data at all
  NOAA installations.
• Contact Bill Moninger at ESRL regarding access
  issues. [phone]
• William.R.Moninger_at_noaa.gov
• Data may not be redistributed in real time.

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Web Display Resources

• Additional training on the use of the web page
  can be found at http//amdar.noaa.gov/videos/.

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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

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Future Plans - WMO

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

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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
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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
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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.
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Supplemental Slides
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Aircraft Weather Data Resolution And Accuracy
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Aircraft Weather Data Resolution and Accuracy
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Aircraft Weather Data Resolution and Accuracy
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Aircraft Weather Data Resolution and Accuracy
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