TWP Darwin Raman Lidar and NSA HSRL Profile Measurements

Description

Aerosol profiles derived from data acquired by two ground-based lidar systems are presented. TWP Darwin Raman lidar data are used to characterize the distribution of aerosols and water vapor over Darwin, Australia. This lidar system, which is very similar to the DOE SGP Raman lidar that has operated extensively for nearly 17 years, began autonomously acquiring aerosol and water vapor profiles in December 2010. Average aerosol extinction, extinction/backscatter, and water vapor profiles are computed as functions of synoptic state, season, aerosol optical thickness, and precipitable water vapor amount. These profiles show that the variability in water vapor and aerosol extinction profiles is smallest during the wet season (Austral summer) and largest during the dry season (Austral winter). Average aerosol extinction/backscatter “lidar ratio” profiles increase with altitude in several cases indicating that the aerosol type often varies with altitude. This variation may be associated with the presence of sea salt aerosol near the surface and biomass burning smoke aloft. The Raman lidar aerosol and water vapor measurements are also examined in the context of columnar aerosol properties derived from coincident Sun photometer measurements. The ground-based High Spectral Resolution Lidar (HSRL) deployed at the NSA autonomously provides calibrated profiles of particulate (i.e. aerosol and cloud) backscatter cross section, optical thickness and circular depolarization at 532 nm. Aerosol extinction profiles derived from the HSRL measurements reveal the presence of elevated aerosol layers. The properties of these aerosol layers are investigated using the HSRL and Sun photometer measurements.