The stratospheric aerosol layer is regularly monitored since 1979 by satellite experiments as Stratospheric Aerosol Measurement (SAM II) and Stratospheric Aerosol and Gas Experiment (SAGE I and II). The satellite spectral measurements of transmission permit one to obtain the spectral variations of extinction from which the aerosol size distribution may be derived. Several correlative measurements with a balloon-borne polarimeter, Radiom¿tre Ballon (Radibal), were conducted during the post-El Chichon period to validate the satellite measurements. The radiance and polarization diagrams of the sunlight scattered by the aerosols, measured from the balloon, were analyzed within the primary scattering approximation, and the retrieved aerosol size distribution was compared with the satellite results. Following the eruption of Mount Pinatubo (June 15, 1991), two flights of Radibal were planned to allow a validation in case of large aerosol amount. Because of the importance of the multiple scatterings the usual inversion of the Radibal measurements was no more valid. We propose here an improved scheme to evaluate the coherence of both SAGE II and Radibal that gives excellent results. ¿ American Geophysical Union 1996