NASA Science Aircraft Monitoring Hurricane Earl on Sept. 2
visible image of Hurricane Earl This visible image of Hurricane Earl heading for North Carolina's coast was captured by the GOES-13 satellite, operated by NOAA. The image was captured at 1732 UTC (1:32 p.m. EDT). Credit: NASA GOES Project/NOAA
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All three of NASA's environmental science aircraft involved in the aerospace agency's Genesis and Rapid Intensification Processes, or GRIP, hurricane research campaign are tracking the path and intensity of Hurricane Earl off the east coast of the United States.

After being downgraded to a Category 3 hurricane Wednesday, Earl was upgraded again to a Category 4 early Thursday morning, with top sustained winds of more than 140 mph. It is considered a threat to the Carolinas and the eastern seaboard as far north as Massachusetts.

NASA's remotely operated Global Hawk and its DC-8 flying laboratory were both in the air Thursday over the hurricane to monitor the storm's intensity and progression.

The high-altitude Global Hawk departed NASA's Dryden Flight Research Center at Edwards, Calif., about 9 p.m. PDT Wednesday evening for a 24-hour mission over Hurricane Earl. The cross-country transit took seven hours, followed by repeated patterns over the hurricane for up to 10 hours while its suite of instruments monitored the storm's characteristics.

Eleven hours into the mission, Global Hawk mission controllers reported the flight was proceeding very well with all payload instruments gathering data and all Satcom links connected. The unmanned aircraft was making repeated passes over the eye of Earl at altitudes in the 60,000-foot range.

The Global Hawk is being controlled by pilots and mission scientists from a control center at NASA Dryden, and was due to return to Edwards at about 9 p.m. PDT Thursday evening.

Meanwhile, the DC-8 flying laboratory, based at the Dryden Aircraft Operations Facility in Palmdale, Calif., went aloft from its field deployment site at Ft. Lauderdale, Fla., at noon EDT Thursday to overfly the hurricane again. As they had done during a mission the preceding day, scientists aboard the converted jetliner worked with a variety of instruments to characterize the powerful storm system as the DC-8's flight path took it directly over the eye of the hurricane several times. In-flight reports indicated that all of the specialized instruments were functioning properly during the flight.

Bjorn Lambrigsten of NASA's Jet Propulsion Laboratory, Pasadena, Calif . is the principal investigator for the HAMSR instrument on the Global Hawk aircraft. The HAMSR is the High Altitude monolithic microwave integrated Circuit (MMIC) Sounding Radiometer and is a microwave atmospheric sounder.

This morning, September 2, Lambrigsten said, "We are indeed flying [over Hurricane Earl]. It turned out that Earl is a well behaved storm, with cloud tops generally well below flight altitude. As a result, we have been able to make multiple passes straight across the eye, with several bulls-eyes."

"We are processing and displaying HAMSR data in real time -- looks great. The Global Hawk took off from NASA Dryden at 9 p.m. PDT Wednesday night (0400 UT) and emerged off the Florida coast seven hours later. We will turn back after 10 hours over the storm and land at Dryden seven hours after that (i.e. at 9 p.m. PDT Thursday, about 24 hours after takeoff)."

"This has been a very good sortie so far, and the pilots are gaining experience and confidence with flying over a storm like this. During the last portion over the storm we are planning to co-fly with the DC-8, which took off from Ft. Lauderdale," Lambrigsten said.

NASA's modified WB-57 weather reconnaissance aircraft, based at the Johnson Space Center's Ellington Field near Houston, is currently deployed to Tampa, Fla., and was also scheduled to overfly Hurricane Earl this week.

The flights by the NASA science aircraft are in close support of operations being flown by four aircraft operated by the National Oceanic and Atmospheric Administration and the National Science Foundation that are also involved in the six-week GRIP campaign. For more information on GRIP, visit: www.nasa.gov/grip/.
Rob Gutro
NASA's Goddard Space Flight Center