These are daylight (top) and low-light camera vies of Eduoard's eye. The daylight image came from the first crossing and low-light during the third eye crossing.Image Credit: D. Fratello, NASA AFRC

NASA's Hurricane Severe Storms Sentinel or HS3 mission flew the unmanned Global Hawk aircraft on two missions between Sept. 11 and 15 into Hurricane Edouard and scored a bullseye by gathering information in the eye of the strengthening storm. Scientists saw how upper-level wind shear was affecting Edouard on the HS3's Global Hawk flight of the 2014 campaign over Sept. 11 and 12, and saw the hurricane strengthen during the sixth flight on Sept. 15 and 16.

NASA's HS3 mission returned to NASA's Wallops Flight Facility, in Wallops Island Virginia for the third year to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin.

NASA's Global Hawk aircraft are unmanned and autonomously operated. That means that pilots located in a control room on the ground continuously monitor the flights. The flight plans are pre-programmed into the Global Hawk's flight control computer from takeoff to landing. However, with guidance from HS3s mission scientists, the pilots often make changes or adjustments to the flight pattern to target particular areas of the storms.

Two of the instruments aboard the Global Hawk that gathered data are the S-HIS and CPL. The S-HIS or Scanning High-resolution Interferometer Sounder gathered a continuous sampling of temperature and relative humidity in the clear-air environment, while the CPL or Cloud Physics Lidar analyzed the vertical structure of aerosols (tiny particles) and the vertical structure of the cloud layers of the hurricane. In addition to the S-HIS and CPL, the Advanced Vertical Atmospheric Profiling System (AVAPS) launched into the hurricane dropsondes that measured profiles of temperature, humidity and full tropospheric wind (winds in every level of the troposphere from top to bottom as the sonde falls).

The Fifth Science Mission Provides a Look at Newly Formed Tropical Storm Edouard's Layers

During the Sept. 11-12 flights over Tropical Storm Edouard, "At 800 millibars (about 2 km or 1.2 miles above the surface) the wind field showed a well-organized cyclonic circulation with winds of at least 35 knots (40.2 mph/64.8 kph) on the eastern side of the storm," said Dr. Scott Braun, HS3 Mission Principal Investigator from NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"The air was generally moist at most dropsonde points except for a few places at large distance from the center and right near the center. The point near the center showed evidence of substantial subsidence (sinking motions) and warming, a relatively weaker wind speed, and a surface pressure of 999 millibars, reminiscent of potentially indicating conditions in a forming eye."

Data from higher levels in the atmosphere, at 400 millibars, also proved interesting. The data showed that Edouard's center of circulation was located northeastward of the lower center at 800 millibars. That means that there was westerly to southwesterly vertical wind shear pushing the higher-level of circulation away from the lower level one. "Secondly," Braun said, "very dry air was being swept into the southern portion of the storm by moderate-strength westerly winds. The combination of shear and dry air aloft likely kept Edouard a weak tropical storm."

Originally posted here:

NASA HS3 Mission Global Hawk's Bullseye in Hurricane Edouard