Lidar validation of SAGE II aerosol measurements after the 1991 Mount Pinatubo eruption

After the Mount Pinatubo volcanic eruption on 15 June 1991 the Stratospheric Aerosol and Gas Experiment (SAGE) II instrument made extensive aerosol extinction retrievals using the limb-viewing technique. In regions of high-aerosol loading, SAGE II was not able to make measurements, resulting in large information gaps both in latitudinal and in longitudinal coverage as well as in the vertical. Here we examine the possibility of filling the vertical gaps using lidar data. We compare every coincident backscattering measurement (at a wavelength of 0.694 μm) from two lidars, at Mauna Loa, Hawaii (19.5°N, 155.6°W), and at Hampton Virginia (37.1°N, 76.3°W), for the 2-year period after the Pinatubo eruption with the SAGE II version 6.0 extinctions at 0.525 and 1.02 μm wavelengths. This is the most comprehensive comparison ever of lidar data with satellite data for the Pinatubo period. We convert backscattering to extinction at the above wavelengths. At altitudes and times with coincident coverage, the SAGE II extinction measurements agree well with the lidar data but less so during the first six months after the eruption, due to the heterogeneity of the aerosol cloud. This shows that lidar data can be combined with satellite data to give an improved stratospheric aerosol data set.