Optical radar measurements of aerosol scattering in the lower stratosphere compared with balloon-borne in-situ measurements of aerosol concentration

This paper will describe measurements of aerosol scattering in the lower stratosphere using a ground-based optical radar and nearly simltaneous balloon-borne in-situ measurements of aerosol concentrations. The experiments were conducted over Laramie, Wyoming, in late June 1972 as part of DOT\´s CIAP Program. Comparative measurements of this type are a necessary part in the analysis and interpretation of optical radar backscatter measurements. A review of the theory will be included, along with a detailed description of Langley\´s 48-inch diameter optical radar system. Emphasis will be placed on data acquisition and analysis, particularly that phase which includes separation of the molecular and aerosol scattering components. Data will be presented in terms of both aerosol scattering function and aerosol concentration using established aerosol distribution models. Aerosol profiles of this type will be shown indicating both a broad 7 km layer and aerosol fine structure layers extending over approximately 1 km in height. Optical radar data taken over a 3 hour period will be shown which clearly indicates variations of some fine structure layers. These time variations will be interpreted in terms of both advection and vertical mixing. A description of the balloon-borne in-situ counter will be given. Balloon measurements of the concentration of particles m diameter, along with ozone concentration and temperature with altitude, will be presented. Finally, a comparison of optical radar data and balloon-borne in-situ measurements will be discussed. Initial comparison indicates good quantitative agreement with respect to the broad aerosol layer.