We have updated our merged ozone data ( MOD ) set using the TOMS data from the new version 8 algorithm . We then analyzed these data for contributions from solar cycle , volcanoes , QBO , and halogens using a standard statistical time series model . We have recently completed a hindcast run of our 3D chemical - transport model for the same years . This model uses off - line winds from the finite - volume GCM , a full stratospheric photochemistry package , and time - varying forcing due to halogens , solar uv , and volcanic aerosols . We will report on a parallel analysis of these model results using the same statistical time series technique as used for the MOD data .