SAGE II aerosol correlative observations: Profile measurements

Abstract

Profiles of Stratospheric Aerosol and Gas Experiment (SAGE) II aerosol extinction measurements are compared with dustsonde‐ and lidar‐derived aerosol extinction profiles during five correlative experiments between November 1984 and July 1986. Six‐channel dustsonde measurements of particle concentration are used to construct a size distribution, then converted to extinction using Mie theory. The two‐wavelength lidar backscatter data are converted to extinction, using model extinction to backscatter values constrained by the standard dustsonde two‐channel ratio. A set of wavelength‐dependent refractive indices is calculated and used in the conversion of both the dustsonde and lidar data to extinction. The November 30, 1984, intercomparison period provided near‐ideal conditions for SAGE II validation. A six‐channel dustsonde and two‐wavelength aircraft lidar system were nearly coincident with the SAGE II measurement. All four profiles of aerosol extinction at 1.02 μm agree very well from the tropopause to 28 km. Selected altitudes were also compared at all four SAGE II aerosol wavelengths: 1.02, 0.525, 0.453, and 0.385 μm. The remaining four intercomparisons vary in quality, but they are very good, considering the time and space gradients and other problems involved. Therefore the SAGE II lower stratospheric aerosol extinction measurements are consistent with dustsonde and lidar measurements for the conditions present during November 1984 to July 1986.