Airborne High Spectral Resolution Lidar and Research Scanning Polarimeter Measurements During RACORO

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) and the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP) were deployed on the NASA B200 King Air aircraft which participated in the RACORO mission during June, 2009. The HSRL measured profiles of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm). The RSP instrument measured total and linearly polarized radiance in nine spectral bands that were used to retrieve column aerosol optical thickness, size distribution, and refractive index, as well as cloud optical thickness and cloud droplet effective radius. The HSRL and RSP collected data during 19 science flights during June 2009; of these 15 flights were coordinated with the CIRPAS Twin Otter, and 16 flights included overpasses of the SGP Central Facility. The HSRL profiles have been used to determine the vertical context for the Twin Otter measurements, characterize the boundary layer and distribution of aerosols within the boundary layer, examine the impact of relative humidity on aerosol parameters, and examine the variability of aerosols near clouds. Aerosol intensive parameters derived from HSRL data are used to infer specific aerosol types and mixtures of those types. An aerosol type associated with urban pollution was found to provide the largest contribution to aerosol optical thickness measured on the campaign. The RSP measurements are being used to derive cloud drop effective radius and width of cloud drop size distribution as well as to derive aerosol properties. Cloud drop effective radius derived from RSP on June 18 was found to be between 5-7.5 μm and in excellent agreement with cloud drop effective radius derived from coincident forward scattering spectrometer probe (FSSP) measurements of cloud drop size distribution near cloud top. RSP retrievals of aerosol properties and coincident ground-based Raman lidar aerosol profiles will also be presented.