Substantial differences in summertime surface UV irradiance between New Zealand and Europe have been reported previously. The main contributors to these differences are differences in total column ozone, differences in Sun-Earth separation between the Southern Hemisphere summer (December/January) and the Northern Hemisphere summer (June/July), and differences in tropospheric pollution. Differences due to higher Northern Hemisphere aerosol extinction have been well documented. Here we present a climatology of ozone profiles measured by balloon-borne sensors launched from Lauder, New Zealand, and from Hohenpeissenberg, Germany, to show that there are also substantial differences in the shapes of ozone profiles, especially during the summer months. A radiative transfer model is then used to investigate the extent to which these profile shape differences contribute to observed UV differences. It is found that the differences in the vertical distribution of ozone amplify existing Northern and Southern Hemisphere differences in UV. Effects can be significant in the UV-B region, but the sign of the effect depends on the solar zenith angle. Consequently, the effect on daily doses of biologically harmful UV radiation is suppressed somewhat, and the differences are responsible for differences in erythemally weighted UV of only a percent or two, which is small compared with other effects. While these effects are relatively small, differences in the vertical profile of ozone can affect the accuracy of satellite retrievals of total column ozone. This analysis shows that the lower tropospheric ozone amounts at Lauder may lead to underestimations of summertime UV from satellite by ~4% at that site.