Spring and summer time ozone and solar ultraviolet radiation variations over Cape Point, South Africa

Abstract

The correlation between solar ultraviolet radiation (UV) and atmospheric ozone is well understood. Decreased stratospheric ozone levels which led to increased solar UV radiation levels at the surface have been recorded. These increased levels of solar UV radiation have potential negative impacts on public health. This study was done to determine whether or not the break-up of the Antarctic ozone hole has an impact on stratospheric columnar ozone (SCO) concentrations and resulting ambient solar UV-B radiation levels at Cape Point, South Africa. At Cape Point, the strongest anti-correlation on clear-sky days was found at solar zenith angle 20° with exponential fit R2 values of 0.71 and 0.66 for total ozone column and SCO, respectively. An average radiation amplification factor of 0.92 was found and the largest decrease in ozone levels occurred during September months. The MIMIOSA-CHIM model showed that the polar vortex had a limited effect on ozone levels at 435 - 440 K for September and 600 K over Cape Point during November. Tropical air-masses more frequently affect the study site, and this requires further investigation.