Rich Ferrare

Combined active-passive remote sensing of aerosol optical properties

Recent assessments of global climate change conclude that the radiative effect of aerosols is one of the largest uncertainties in our ability to predict future climate change. A myriad of new sensors and satellite missions are being designed to address this major question confronting credible prediction of climate change. The NASA Langley Airborne A-Band Spectrometer (LAABS) is a recently developed aircraft instrument that provides high spectral resolution (~0.03 nm) radiance measurements of reflected sunlight over the oxygen A-band spectral region centered near 765 nm. High resolution O2 A-band spectrometry of reflected sunlight is a promising new approach for remote sensing of aerosol and cloud optical properties. While the LAABS instrument provides valuable data on a stand-alone basis, greater scientific return may be realized by combining the A-band spectra with coincident lidar measurements that supply additional information on the vertical distribution of the aerosol. In particular, an instrument suite that combines LAABS with the new airborne High Spectral Resolution Lidar (HSRL) has the potential to provide a comprehensive suite of aerosol and cloud optical property measurements never before achieved. In this paper, we investigate the combined use of LAABS and HSRL measurements to infer aerosol single scatter albedo. We explore the information content of the O2 A-band reflectance spectra and, in particular, the advantages offered by high resolution A-band spectrometers such as LAABS. The approach for combined LAABS/HSRL retrievals is described and results from simulation studies are presented to illustrate their potential for retrieval of single scatter albedo.