Global Hawk observes the Saharan Air Layer through the Cloud Physics Lidar (CPL) during Hurricane Nadine

NASA's Hurricane and Severe Storm Sentinel mission(HS3) is a mission that brings together several NASA centers with federal and university partners to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin. Among those factors, HS3 will address the controversial role of the hot, dry and dusty Saharan Air Layer(SAL) in tropical storm formation and intensification and the extent to which deep convection in the inner-core region of storms is a key driver of intensity change.

One instrument used to investigate the SAL is the cloud physics lidar(CPL). CPL uses a laser to measure vertical profiles of dust; a dropsonde system that releases small instrumented packages from the aircraft that fall to the surface while measuring profiles of temperature, humidity, and winds; and an infrared sounder that measures temperature and humidity in clear-sky regions.The CPL is an airborne lidar system designed specifically for studying clouds and aerosols. CPL will study cloud- and dust-layer boundaries and will provide optical depth or thickness of aerosols and clouds

On Sept. 11 and 12, during the 2012 HS3 mission, the NASA Global Hawk aircraft covered more than one million square kilometers (386,100 square miles) going back and forth over the storm in a gridded fashion in what's called a "lawnmower pattern."

Dropsonde data from HS3's flights show temperature and humidity conditions in the storm. In this movie, the dropsondes are colored with the relative humidity data where blue represents dry air and red represents moist air.

For more information about NASA's HS3 mission, visit:

http://www.nasa.gov/hs3