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In 1956, the US Weather Bureau, reacting to the devastation of three consecutive hurricane strikes along the east coast of the United States, received Congressional funding to establish the National Hurricane Research Project to conduct research on tropical cyclones that would advance our scientific understanding of these storms and provide the means to improve the accuracy of future hurricane forecasts.
During this process, the NHRP began to ponder the horizontal thermal and vertical wind structures in the upper Troposphere / lower Stratosphere region of tropical cyclones. At the time, there were no high-altitude aircraft adequate to probe these upper regions over the tops of tropical cyclones, except the U-2.
Beginning in early 1960, the AFCRL made available a U-2 to the Weather Bureau's hurricane research project (NHRP) and its component Project Stormfury (an experimental hurricane modification project) providing high-altitude photographs and gathering meteorological data in the Troposphere region over the hurricanes.
Storms flown by the AFCRL U-2 included Hurricanes Donna (60), Carla (61), Esther (61), Flora (63), Beulah (63), Ginny (64), Isbell (64), Betsy (65) and Beulah (67) to name just a few.
Although these U-2 hurricane flights were flown in direct support to hurricane research, there were a number of hurricanes flown by these U-2 in association with other research projects not directly related to hurricane research.
Between 1962-66, AFCRL research U-2 aircraft were utilized in a high-altitude Ozone Research Project to sample and measure Ozone concentrations in the upper atmosphere. As part of this project, a specially equipped U-2 aircraft probed the eye of Hurricane Ginny to take the first ever Ozone measurements in a tropical cyclone.
On 22 October 1963, the AFCRL "Ozone" U-2 flew up and over the top of Hurricane Ginny and down into its eye to make Ozone measurements. The aircraft also captured horizontal thermal (temperature) structure measurements and 180-degree panoramic cloud photographs for the Weather Bureau.
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A similar Ozone sampling, thermal measuring and cloud photo reconnaissance mission was flown about a year later, into Hurricane Isbell. The AFCRL U-2 penetrated into the upper region of Hurricane Isbell at approximately 55,000 feet - as the storm was off the coast of Florida, near Key West.
The flight plan included a vertical probe of Isbell's eye, similar to Ginny, but was terminated early before a deeper probe of the eye was made, due to a thick layer of dense Cirrus-like clouds in the eye's center and increasing turbulence at various flight levels around the storm.
Another U-2 Hurricane flight was conducted during Hurricane Beulah in September 1967. This research flight was conducted in association with the Flight Dynamics Laboratory, of the Air Force's Systems Command.
The High-altitude Clear Air Turbulence (HICAT) Project (1964-68) was established to provide fine scale, true (wind) gust, velocity measurements in continuous wave length "clear air turbulence" at altitudes between 45,000 and 70,000 feet - as correlated with meteorological and geophysical conditions.
This project introduced the U-2 aircraft into another existing Air Force "Clear Air Turbulence" (or CAT) program to scan various areas of the world for clear air turbulence.
Operating from US Air Force and allied air bases around the world, the HICAT U-2 flew missions from the US, Eastern Canada, Alaska, Hawaii, Australia, New Zealand, Puerto Rico (the Caribbean), Panama, the UK and France.
One of the Edwards AFB, Flight Test Center's upgraded U-2Ds (aircraft #56-6722) was modified with a specialized nose - mounted, fixed vane, gust probe and a Rosemont Lozezal temperature sensor, connected to a digital pulse code modulation recording system.
Of the 285 clear air turbulence flights flown between 1962-1968, the U-2 flew 232 flights at HICAT Altitudes above 65,000 feet.
On 22 September 1967, this HICAT U-2 flew a hurricane surveillance mission into Hurricane Beulah to record the stratospheric conditions around and over the storm - including any clear air turbulence within the surrounding environment.
As the hurricane made landfall in southern Texas, the HICAT U-2 made several counter-clockwise descending loops around the top of Hurricane Beulah's eye, from 65,000 feet down through 55,000 to 45,000 feet or to the tops of the hurricane's eye wall clouds. The U-2 took detailed temperature, wind and air motion measurements throughout the flight.
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