The JPL Laser Hygrometer (JLH), PI Robert Herman, was flown on board the Northrop-Grumman Corporation (NGC) Beechcraft G-II aircraft on March 5, 2015, taking water vapor measurements in the upper troposphere over the NASA Armstrong Flight Research Center (AFRC) test range.  The aircraft took off at 11:00 am and landed around 2:30 pm, loosely coordinated with the landing of the AFRC Global Hawk (ATTREX/CAST), enabling the comparison of meteorological data between the two sensors.

Preliminary indications are that the JLH instrument performed well.  Near-real-time water vapor data was sent by Ethernet to the vehicle management computer onboard the aircraft.  A commercial humidity sensor was also flown, but it lacked the requisite sensitivity at high altitude, low humidity conditions.