Approximate separation of volcanic and 11‐year signals in the SBUV‐SBUV/2 total ozone record over the 1979‐1995 Period

Abstract

The combined Nimbus 7 SBUV, NOAA 11, and preliminary NOAA 9 SBUV/2 monthly zonal mean total ozone data set, extending from January 1979 to December 1995, is analyzed with a multiple regression statistical model that includes a term to describe the direct effect of volcanic aerosols on total ozone. Outside of polar regions, which are not included in this analysis, the volcanic regression coefficients in the northern hemisphere are negative (consistent with heterogeneous chemical losses of ozone on volcanic sulfate aerosols) and reach their maximum values between 40°N–60°N latitude. Although inclusion of the aerosol term in the statistical model introduces some additional uncertainty to the derived solar response, statistically significant values of the solar coefficients are found in northern and southern subtropical regions throughout the year, with maximum amplitudes of ∼2.5% at 30° latitude in both hemispheres during winter. We conclude that the 11‐year signal in the SBUV‐SBUV/2 total ozone record is approximately separable from volcanic aerosol effects.