Six-wavelength lidar observations of European and Asian aerosol plumes

As part of the Indian Ocean Experiment (INDOEX) anthropogenic aerosols advected from the Indian subcontinent to the Indian Ocean were observed with a unique six-wavelength aerosol lidar at Maldives International Airport in the spring of 1999. European aerosol plumes were observed during the Aerosol Characterization Experiment 2 (ACE 2) in Sagres, Portugal, in the summer of 1997, and during the Lindenberg Aerosol Characterization Experiment (LACE), in Lindenberg, Germany, in the summer of 1998. The eleven-channel aerosol lidar allows us to detect signals elastically backscattered by air molecules and particle and inelastically (Raman) scattered by nitrogen and water vapor. Profiles of the particle backscatter coefficient at the six wavelength between 355 and 1064 nm, of the volume extinction coefficient of the particles at 355 and 532 nm, as well as the vertical distribution of the water vapor mixing ratio are determined from the lidar data. A sophisticated inversion scheme is applied to determine the physical parameters of the particles from the spectrally resolved optical properties. The set of observational data is used to estimated the aerosol impact on climate.

Several pollution outbreaks from the European and the Indian continent could be observed. These highly polluted situations are compared with very clean cases. Typical measurements will be presented. Theses examples clearly show the need for vertically resolved aerosol observations and underline the importance of lidar in this context.