Juan C. Antuña¹, Alan Robock² and Georgiy L. Stenchikov²

¹Camagüey Lidar Station, Camagüey Meteorological Center, Camagüey 70100, Cuba
2Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA

When comparing vertical extinction profiles of stratospheric aerosols from different instruments, and for using this information in data assimilation, it is important to characterize the variability of the observations. For the largest eruption of the 20th century, the June 15, 1991 Mount Pinatubo eruption in the Philippines, we made use of both SAGE II measured and lidar-derived aerosol extinction profiles to quantify the magnitude of such variability. We used SAGE II sunset and sunrise measurements that were coincident in space and time, as well as lidar measurements taken in consecutive days and two days apart. We found that aerosol variability plays a major role in the differences between space and time coincident stratospheric aerosol extinction profiles measured by SAGE II and derived by lidars. We can characterize the magnitudes of the variability into two main periods after the eruption. The first one, covering the period June 1991 to January 1992, had higher differences resulting from the higher variability in the inhomogeneous stratospheric aerosol cloud. The second one, from around February 1992 on, shows lower differences between both instruments because of the comparatively lower variability of the more homogeneous cloud. During the first period, for time lapses of 12 to 48 hours, the aerosol extinction had 50-150% absolute differences at the core of the cloud. The geometrical and temporal structure of the SAGE II sampling is not capable of resolving the space and time scales at which this variability takes place. This variability should be taken into account when designing future satellite instruments and experimental campaigns. Future aerosol data assimilation should consider the magnitude of the aerosol variability for each period individually for quality control purposes.