ATM-9500186 Rosen This project involves concurrent balloon soundings from a mid-latitude site in the northern hemisphere (Laramie, Wyoming, 41(N), and a mid-latitude site in the southern hemisphere (Lauder, New Zealand, 45(S). Newly developed balloon borne instrumentation will be employed to obtain high resolution profiles of aerosol backscatter at two wavelengths, ozone, relative humidity, air temperature and pressure throughout the troposphere and stratosphere. The results will contribute to the present established record of atmospheric measurements at both sites as well as create new knowledge. Specifically, the final decay of the Mt. Pinatubo eruption of 1991 will be documented and a new value for the magnitude of stratospheric aerosol background determined. The tropospheric measurements over Lauder will help address the general lack of high vertical resolution data that is available relating to tropospheric aerosols in the remote southern hemisphere. A direct comparison of aerosols at the northern and southern mid-latitude sites should provide uniquely contrasting data for the identification of atmospheric processes and the assessment of anthropogenic components.