Analysis of tropospheric ozone profiles over Johannesburg based on MOZAIC (Measurement of Ozone aboard Airbus In-service Aircraft) data has revealed a number of distinct patterns which are distinguished on the basis of the height and magnitude of ozone peaks. A multivariate cluster analysis was used to classify the profiles. The focus of this paper is on a summer pattern in which a single mid-tropospheric ozone peak is detected. Back trajectory analysis revealed that the high ozone could be ascribed to a continental source region further north over central Africa. A case study of a high ozone event in this region showed that the most likely source of elevated ozone was localised biomass burning followed by convective uplift and subsequent long range transport in the anticyclonic gyre over southern Africa. The relative importance of this pattern in determining the characteristics of summer ozone over Johannesburg are discussed.