Global horizontal sounding technique

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The Global horizontal sounding technique (GHOST) program was an atmospheric field research project in the late 1960s for investigating the technical ability to gather weather data using thousands of simultaneous long-duration balloons for very long-range global scale numerical weather prediction[1] in preparation for the Global Atmospheric Research Program (GARP).[2]


Unlike radiosonde balloons which collect vertical atmospheric sounding data over the release point during a relatively short ascent lasting a few hours, horizontal sounding balloons stay aloft for much longer periods lasting several weeks or months, floating at a constant-density altitude.

The GHOST design explored the performance a superpressure balloon with a spherical two-layer PET film envelope holding the gas inside at a higher pressure than the surrounding atmosphere, allowing it to maintain a nearly constant altitude. These gas balloons float at a constant density altitude,[3] where the balloon displaces a mass of air equal to its own mass. Expansion of the lifting gas due to solar heating, as in a zero-pressure balloon,[1] is avoided in a superpressure balloon. The inextensible PET film allows the pressure to rise as the gas is heated, rather than allow the volume to expand. This allows them to drift with, and track, horizontal atmospheric air currents at a constant air pressure level (a constant altitude) above the Earth's surface.

The electronics payload was suspended below the balloon on a tether that also acted as a high frequency band radio antenna. The GHOST payload included a sun angle sensor that varied the repetition rate of its Morse code radio signal to allow technicians on the ground to locate it using an HF receiver and a set of sun angle tables.[1]


Although 231 GHOST balloons were launched in a four-year period between March 1966 and December 1969[4][5][6] the flight lifetime at low altitudes (below 12 km) proved to be too short, despite many redesigns of the balloon system to improve the performance. Without both upper level and lower level long-duration balloons, the GHOST system idea was deemed infeasible for the GARP requirements. The GHOST program was superseded by research on the 'Carrier Balloon' system, also known as 'Mother GHOST'.[2]


On September 29, 1968 a 10-foot (3-meter) GHOST balloon at an altitude of approximately 52,000 feet (16,000 meters) completed a full 365 days in flight, becoming the first balloon to fly for a full year.[1] This record-breaking balloon, launched from Christchurch, New Zealand by the U.S. National Center for Atmospheric Research (NCAR), continued to fly for an additional 76 days, completing 35 circumnavigations of the Earth. The longest flight of the program was 744 days, or just over two years. The balloons could not be flown in the Northern Hemisphere because the Soviet Union would not permit overflights at the time.[7]

The Ghost Project based at Christchurch Airport New Zealand was still running in 1973. A Ghost project balloon was seen by a member of the public in 1985.[citation needed]

Vincent E. Lally of NCAR received the Otto C. Winzen Lifetime Achievement Award from the American Institute of Aeronautics and Astronautics in 2003 for his pioneering work in the application and development of superpressure balloons for worldwide atmospheric measurements, including the GHOST program.[8][9] Winzen was a pioneer of modern ballooning, and this award recognizes outstanding contributions to the advancement of free-flight balloon systems or related technologies.


  1. ^ a b c d "GHOST program". The Illustrated Encyclopedia of Aviation and Space. 6. Los Angeles: A.F.E. Press. 1971. pp. 978–979. LCCN 68014013. 
  2. ^ a b Frykman, Robert W; Vincent E Lally (1971). "A carrier balloon for tropical soundings". NCAR Tech Note. TN/EDD-63. 
  3. ^ Voss, Linda. "Ballooning and Meteorology in the Twentieth Century". U.S. Centennial of Flight Commission. Retrieved 2007-10-17. 
  4. ^ Lally, Vincent E (1970). "Superpressure Balloon Flights from Christchurch, New Zealand, July 1968 - December 1969". NCAR Tech Note. TN-48. 
  5. ^ Lally, Vincent E (1969). "Superpressure Balloon Flights from Christchurch, New Zealand August 1967 - June 1968". NCAR Tech Note. TN-38. 
  6. ^ Lally, Vincent E (1968). "Superpressure Balloons for Horizontal Soundings of the Atmosphere". NCAR Tech Note. TN-28. 
  7. ^ Hosanky, David (2004-04). "UCAR Staff Notes: Kaye Howe wins YWCA award". UCAR Communications, Staff Notes Monthly. University Corporation for Atmospheric Research. Retrieved 2007-10-17.  Check date values in: |date= (help)
  8. ^ "Winzen Award Recipient - 2003". American Institute of Aeronautics and Astronautics. Retrieved 2007-10-17. 
  9. ^ Hosansky, David (2003-03). "Vin Lally wins prestigious ballooning award". UCAR Communications, Staff Notes Monthly. University Corporation for Atmospheric Research. Retrieved 2007-10-17.  Check date values in: |date= (help)

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