AERONET, airborne HSRL, and CALIPSO aerosol retrievals compared and combined: A case study

On 4 August 2007 a unique opportunity for the intercomparison of aerosol retrievals occurred as part of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and Twilight Zone (CATZ) campaign in the Washington, D. C., urban complex. During the course of the experiment, several Aerosol Robotic Network (AERONET) Cimel Sun photometers were deployed along the CALIPSO track, together with NASA Langley Research Center's airborne High Spectral Resolution Lidar (HSRL) instrument flying overhead. A series of daytime coincident measurements was made by the various instruments, permitting a number of important opportunities for the intercomparison of the various instrumental measurements of aerosols as well as evaluation of the Constrained Ratio Aerosol Model-fit (CRAM) technique for aerosol retrievals from elastic backscatter lidar. The results from the intercomparison are discussed as an illustrative case study in sensor combination and aerosol retrieval methodology.