Raman-shifted Eye-safe Aerosol Lidar (REAL) observations during the Canopy Horizontal Array Turbulence Study (CHATS)

The Raman-shifted Eye-safe Aerosol Lidar (REAL, www.lidar.ucar.edu) was deployed during the Canopy Horizontal Array Turbulence Study (CHATS) field experiment from 15 March through 11 June 2007 in Dixon, California. It was the first field deployment of the instrument in which it operated continuously and unattended for the majority of the experiment. The REAL, an eye-safe, ground-based, scanning, elastic-backscatter aerosol lidar, was located 1.6 km north of the NCAR ISFF 30-m tall tower. Almost-horizontal scans (PPI scans) intersected the tower just a few meters above the canopy. Vertical scans (RHI scans) were directed at an azimuth angle just a few meters adjacent to the tower. During approximately half of the experiment, PPI and RHI scans were collected in an interleaved fashion to provide time-lapse animations in both dimensions simultaneously. At other times, PPI or RHI scans were collected for approximately 10-minute durations to obtain high-resolution time-lapse visualizations. Overall, the data set is a remarkable, almost-continuous, visualization of the boundary layer structure and motion. Within it, several very interesting phenomena are especially worthy of showcasing. For example, during weakly stable conditions, gravity wave activity and bursts of intermittent turbulence are observed in the surface layer. On several occasions, dramatic sea-breeze fronts pass over the site. This presentation will highlight the most interesting features in the data set, mainly in the form of time-lapse animations.