Source region plume characterisation of the interior of South Africa as observed at Welgegund - Beukes, J.P; Vakkari, V; van Zyl, P.G; Venter, A.D; Josipovic, M; Jaars, K; Tiitta, P; Kulmala, M; Worsnop, D; Pienaar, J.J; Virkkula, A; Laakso, L (Clean Air Journal, 2013)