Since 1976 the stratospheric aerosol layer has been continually monitored at IMK-IFU by lidar measurements [Jäger, 2005] (see figure below), since 1991 as a contribution to the NDACC. The principal sources of stratospheric aerosol are major volcanic eruptions, in particular those of El Chichon (1983, Mexico) and Mt. Pinatubo (1991, Philippines). After these two eruptions the aerosol loading of the stratosphere was so high that heterogeneous ozone depletion and a lowering of the temperature could be observed. Air traffic has been speculated on to yield another, growing contribution to the stratospheric aerosol layer. The low backscatter coefficients during the current extended background period do not support this idea. We currently investigate the influence of strong wild fires on the background aerosol in the stratosphere.
Aerosol backscatter coefficients integrated from 1 km above the tropopause to the layer top; the vertical arrows mark major volcanic eruptions.
Jäger, H.: Long-term record of lidar observations of the stratospheric aerosol layer at Garmisch-Partenkirchen, J. Geophys. Res., 110, D08106, doi:10.1029/2004JD005506, 2005.