Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 5 2004 10.5194/acpd-4-5831-2004 http://www.atmos-chem-phys-discuss.net/4/5831/2004/ http://www.atmos-chem-phys-discuss.net/4/5831/2004/acpd-4-5831-2004.html http://www.atmos-chem-phys-discuss.net/4/5831/2004/acpd-4-5831-2004.pdf 5831 5854 2004-09-28 Fluorescence from atmospheric aerosol detected by a lidar indicates biogenic particles in the stratosphere F. Immler fimmler@awi-bremerhaven.de D. Engelbart O. Schrems Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany German Weather Service, Meteorological Observatory Lindenberg, Am Observatorium 12, 15848 Lindenberg, Germany With a lidar system that was installed in Lindenberg/Germany, we observed in June 2003, an extended aerosol layer at 13 km altitude in the lowermost stratosphere. This layer created an inelastic backscatter signal which we interpret as laser induced fluorescence from aerosol particles. Also, we find evidence for inelastic scattering in a smoke plume from a forest fire that we observed in the troposphere. Fluorescence from ambient aerosol had not yet been considered detectable by lidar. However, organic compounds such as polycyclic aromatic hydrocarbons sticking to the aerosol particles, or bioaerosol such as bacteria, spores or pollen fluoresce when excited with UV-radiation in a way that is detectable by our lidar system. Therefore, we conclude that fluorescence from organic material released by biomass burning creates the inelastic backscatter signal that we measured with our instrument and thus demonstrate a new and powerful way to characterize aerosols by a remote sensing technique. The stratospheric aerosol layer that we have observed in Lindenberg for three consecutive days is likely to be a remnant from Siberian forest fire plumes lifted across the tropopause and transported around the globe.