AEROSOL EFFECT ON UMKEHR OZONE PROFILES USING STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II MEASUREMENTS

This study examines 1211 cases of coincident ozone profiles derived fr om 1164 Umkehrs and 928 Stratospheric Aerosol and Gas Experiment II (S AGE II) profiles within 1000 km and 12 hours between October 1984 and April 1989 to study the stratospheric-aeroso1 effect on Umkehr ozone p rofiles. Because of the close correspondence of stratospheric aerosol optical depth at the SAGE II-measured 0.525-mu m wavelength and the ex trapolated 0.32 Umkehr wavelength determined in this study, we use the 0.525-mu m data to determine the aerosol effect on Umkehr profiles. A t the 95% confidence level, we find the following errors to the Umkehr ozone amounts: in Umkehr layer 9 (-2.9+/-2.1), layer 8 (-2.3+/-1.1), layer 7 (0.1+/-1.1), layer 6 (2.2+/-1.0), layer 5 (-1.5+/-0.8), and la yer 4 (-2.4+/-1.7) in percent ozone amount per 0.01 stratospheric aero sol optical depth. These results agree with previous theoretical and e mpirical studies within their respective error bounds in layers 9, 8, and 7. The results in layers 6, 5, and 4 differ significantly from tho se in previous works. Using only those eight stations with more than 4 7 coincidences results in mean aerosol effects that are not significan tly different from the 14-station results. Because SAGE II and Umkehr produce different ozone retrievals in layer 9 and because the intralay er correlation of SAGE II ozone and aerosol in layer 9 is nonzero, one must exercise some caution in attributing the entire SAGE II-Umkehr d ifference in this layer to an aerosol effect.