Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols

Abstract. Spatio-temporal distributions of stratospheric aerosols, measured by the ORA instrument from August 1992 until May 1993, are presented in the latitude range (40° S–40° N). Particle total number density, mode radius and distribution width are derived and interpreted. The respective roles of advection, sedimentation and coagulation are discussed. We also identify clear transport/sedimentation patterns and we show the enhancement of coagulation in stagnation regions. Efficient transport of aerosol particles up to 50 km is suggested.

Key words. Atmospheric composition and structure (aerosols and particles; middle atmosphere-composition and chemistry; volcanic effects)