"The AC&C/SPARC ozone database covers the period 1850 to 2100 and can be used as forcing in climate models that do not include interactive chemistry. The historical part of the AC&C/SPARC ozone database spans the period 1850 to 2009 and consists of separate stratospheric and tropospheric data sources: (1) A multiple linear regression analysis of SAGE I+II satellite observations and polar ozonesonde measurements is used for the stratospheric dataset during the well-observed period from 1979 to 2005. The regression includes terms representing equivalent effective stratospheric chlorine (EESC) and the 11-year solar cycle variability. The EESC regression coefficients are used to extrapolate that data back in time, and form a stratospheric ozone time series backward to cover the entire historical time period 1850-2006. (2) Tropospheric data are derived from the chemistry-climate models Community Atmosphere Model (CAM) version 3.5 and the NASA-GISS PUCCINI model. Both models simulate tropospheric and stratospheric chemistry with feedback to the radiation and were driven by the recently available historical (1850-2000) emissions succinctly described in Lamarque et al. (ACP, 2010)."