Solar Cycle Variability in Tropical Column Ozone Yung, Liang, Li, Jiang and Camp Using an empirical orthogonal function (EOF) method (Camp et al. 2003), we analyzed the Merged Ozone Data (MOD) set from late 1978 to the present. The decadal variability of column ozone in the tropics follows that of the sun over three solar cycles. The peakto-peak amplitude is about 10 DU (Dobson Units), consistent with the conclusion of Camp et al. (2003), who analyzed the MOD data up to and including 2000. Previous attempts to model the amplitude of the observed solar cycle in ozone were unsuccessful, as models tended to underestimate the solar cycle effect. Using the WACCM (Whole Atmosphere Community Climate Model) in combination with the latest satellite measurements of solar variability in the UV (McClintock et al. 2005; Harder et al. 2009), we report results that simulate the observations correctly for the first time. The implications for solar forcing on middle atmosphere chemistry are discussed.