The National Center for Atmospheric Research eye-safe high spectral resolution lidar: a facility for airborne and ground based measurements of the optical properties of atmospheric aerosols and clouds

The National Center for Atmospheric Research (NCAR) has a high spectral resolution lidar (HSRL) developed by the University of Wisconsin. This lidar can be deployed on the National Science Foundations (NSF) Gulfstream V (GV) aircraft or a custom intermodal shipping container (6.058m x 2.438m x 2.591m (LWH). The HSRL has been successfully deployed on the NSF GV aircraft for the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC project (TORERO) in January-February 2012. TORERO operations were base out of Antofagasta, Chile and San Jose, Costa Rica and were investigating remote regions of the Pacific ocean. The HSRL was used to characterize the optical properties of the marine boundary layer aerosols and clouds: back scatter cross section, extinction coefficient, depolarization ratio and integrated optical depth. Mid-level tropospheric and stratospheric aerosols were also observed with the HSRL and their optical properties characterized. The HSRL is capable of making either zenith or nadir pointing measurements from the NSF GV aircraft. The transition between zenith and nadir pointing can be accomplished in a few seconds. This ability to make calibrated measurements of the optical properties of atmospheric aerosols and clouds either above or below the aircraft is unique to this instrument and extremely useful. The real-time display information can be used to direct the aircraft to interesting regions of the atmosphere, either clean regions or aerosol layers, where in-situ instruments can be used to gather more data.

The system has also been operated from the ground based intermodal shipping container located at the Foothills campus of NCAR. The HSRL occupies about half of the container and the other half of the container is configured to contain a dual wavelength, W and Ka band, and dual polarization cloud radar. The information from both the lidar and radar will then be combined to increase the knowledge of the atmospheric processes that are occurring. The radar is under development at this time and results of preliminary test will be presented. The HSRL has also been modified to identify and characterize oriented scatterers by measuring the full backscatter phase matrix. Developments are currently underway for particle identification using the optical properties measured by the lidar and the radar. Results of the TORERO field program, measurements of oriented scatterers and particle identification will be shown.