The Georgia Tech Research Institute (GTRI) has developed a new type of LIDAR system for monitoring profiles of atmospheric refractive turbulence. The system makes real-time measurements by projecting a laser beam to form a laser beacon at several successive altitudes. The beacon is observed with a multiple-aperture telescope and the motion of the beacon images from each altitude is characterized as the differential image motion variance. An inversion algorithm has been developed to retrieve the turbulence profile. GTRI built a brassboard version of the LIDAR instrument and tested it in October and December 2007, with truth data from scintillometers and from balloon-borne microthermal probes. The tests resulted in the first time-height diagram of the strength of turbulence ever recorded by a LIDAR.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.