Global horizontal sounding technique
Encyclopedia
The Global horizontal sounding technique (GHOST) program was an atmospheric field research project for gathering weather data with balloon
s. Unlike radiosonde
balloons which collect vertical atmospheric sounding
data over the release point during a relatively short ascent lasting a few minutes, horizontal sounding balloons stay aloft for much longer periods lasting several weeks or months, floating at a predetermined altitude. The GHOST program studied the movement of upper-air currents and tested the feasibility of using horizontal sounding techniques to provide the necessary weather observations for very long-range global scale numerical weather prediction
. The GHOST project was part of the Global Atmospheric Measurements Program (GAMP). Eighty-eight GHOST balloons were launched in a 10-year period starting in March 1966.
The GHOST design used a superpressure balloon
with an aluminized 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 balloon
s float at a constant density altitude
, where the balloon displaces a mass of air equal to its own, and are not affected by solar heating and subsequent expansion of the lifting gas
as in a zero-pressure balloon. This makes them suitable for studying atmospheric motions at a constant pressure level above the 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.
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. 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 circumnavigation
s 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.
Vincent E. (Vin) 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. Winzen was a pioneer of modern ballooning, and this award recognizes outstanding contributions to the advancement of free-flight balloon systems or related technologies.
Balloon (aircraft)
A balloon is a type of aircraft that remains aloft due to its buoyancy. A balloon travels by moving with the wind. It is distinct from an airship, which is a buoyant aircraft that can be propelled through the air in a controlled manner....
s. Unlike radiosonde
Radiosonde
A radiosonde is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz and both types may be adjusted slightly higher or lower as required...
balloons which collect vertical atmospheric sounding
Atmospheric sounding
An atmospheric sounding is a measurement of vertical distribution of physical properties of the atmospheric column such as pressure, temperature, wind speed and wind direction , liquid water content, ozone concentration, pollution, and other properties...
data over the release point during a relatively short ascent lasting a few minutes, horizontal sounding balloons stay aloft for much longer periods lasting several weeks or months, floating at a predetermined altitude. The GHOST program studied the movement of upper-air currents and tested the feasibility of using horizontal sounding techniques to provide the necessary weather observations for very long-range global scale numerical weather prediction
Numerical weather prediction
Numerical weather prediction uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of computer simulation in the 1950s that numerical weather predictions produced realistic...
. The GHOST project was part of the Global Atmospheric Measurements Program (GAMP). Eighty-eight GHOST balloons were launched in a 10-year period starting in March 1966.
The GHOST design used a superpressure balloon
Superpressure balloon
A superpressure balloon is a style of aerostatic balloon where the volume of the balloon is kept relatively constant in the face of changes in the temperature of the contained lifting gas. This allows the balloon to keep a stable altitude for long periods...
with an aluminized PET film
PET film (biaxially oriented)
BoPET is a polyester film made from stretched polyethylene terephthalate and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation.A variety of companies manufacture boPET and other...
envelope holding the gas inside at a higher pressure than the surrounding atmosphere, allowing it to maintain a nearly constant altitude. These gas balloon
Gas balloon
A gas balloon is any balloon that stays aloft due to being filled with a gas less dense than air or lighter than air . A gas balloon may also be called a Charlière for its inventor, the Frenchman Jacques Charles. Today, familiar gas balloons include large blimps and small rubber party balloons...
s float at a constant density altitude
Density altitude
Density altitude is the altitude in the International Standard Atmosphere at which the air density would be equal to the actual air density at the place of observation, or, in other words, the height when measured in terms of the density of the air rather than the distance from the ground...
, where the balloon displaces a mass of air equal to its own, and are not affected by solar heating and subsequent expansion of the lifting gas
Lifting gas
Because of the Archimedes' principle, a lifting gas is required for aerostats to create buoyancy. Its density is lower than that of air . Only certain lighter than air gases are suitable as lifting gases.- Hot Air :...
as in a zero-pressure balloon. This makes them suitable for studying atmospheric motions at a constant pressure level above the surface.
The electronics payload was suspended below the balloon on a tether that also acted as a high frequency
High frequency
High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...
band radio antenna. The GHOST payload included a sun angle sensor that varied the repetition rate of its Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
radio signal to allow technicians on the ground to locate it using an HF receiver and a set of sun angle tables.
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. This record-breaking balloon, launched from Christchurch
Christchurch
Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of...
, New Zealand by the U.S. National Center for Atmospheric Research
National Center for Atmospheric Research
The National Center for Atmospheric Research has multiple facilities, including the I. M. Pei-designed Mesa Laboratory headquarters in Boulder, Colorado. NCAR is managed by the nonprofit University Corporation for Atmospheric Research and sponsored by the National Science Foundation...
(NCAR), continued to fly for an additional 76 days, completing 35 circumnavigation
Circumnavigation
Circumnavigation – literally, "navigation of a circumference" – refers to travelling all the way around an island, a continent, or the entire planet Earth.- Global circumnavigation :...
s 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
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
would not permit overflights at the time.
Vincent E. (Vin) Lally of NCAR received the Otto C. Winzen
Otto C. Winzen
Otto C. Winzen was a German - American aeronautics engineer who made significant advances in the materials and construction of balloons after World War II....
Lifetime Achievement Award from the American Institute of Aeronautics and Astronautics
American Institute of Aeronautics and Astronautics
The American Institute of Aeronautics and Astronautics is the professional society for the field of aerospace engineering. The AIAA was founded in 1963 from the merger of two earlier societies: the American Rocket Society , founded in 1930 as the American Interplanetary Society , and the Institute...
in 2003 for his pioneering work in the application and development of superpressure balloons for worldwide atmospheric measurements, including the GHOST program. Winzen was a pioneer of modern ballooning, and this award recognizes outstanding contributions to the advancement of free-flight balloon systems or related technologies.
External links
- MSN Encarta: Ballooning (Archived 2009-10-31)