Mineral dust observed with AERONET Sun photometer, Raman lidar,and in situ instruments during SAMUM 2006: Shape-independentparticle properties

摘要

Aerosol Robotic Network (AERONET) Sun photometer observations were carried outat Ouarzazate, Morocco, during the Saharan Mineral Dust Experiment (SAMUM) 2006.Data from one measurement day, 19 May 2006, are used to derive particle optical andmicrophysical parameters with AERONET's latest version of light-scattering model fornon-spherical particle geometry. In our analysis we also make use of a novel measurementchannel at 1638 nm wavelength. We compare the results to data products obtained byairborne high-spectral-resolution lidar, several ground-based Raman lidar, and airborneand ground-based in situ measurement platforms. We chose that specific measurement daybecause the dust plume was vertically well mixed. Extinction coefficients fromAERONET Sun photometer and lidar observations and in situ measurements agree well.Angstrom exponents from Sun photometer and lidar are in close agreement, too. Airbornein situ measurements of dust particle size distributions show larger effective radii thaninferred from the AERONET data. Complex refractive indices that are derived with theAERONET algorithm differ from the values obtained with different independent techniques employed in our study. The single-scattering albedo was derived from theairborne observations of particle size distributions and complex refractive indices. Single-scattering albedo differs to the value inferred from the AERONET data. The differencesmay be attributed to the different effective radii that we obtained from the varioustechniques. The differences between the data products from the various measurementplatforms, however, cannot be generalized, as we could only test data for onemeasurement day. An analysis of additional measurements is under way.