1. Department of Geography and Environmental Studies, University of Limpopo, Sovenga 0727, South Africa
2. Risk and Vulnerability Science Center, University of Limpopo, Sovenga 0727, South Africa
3. Physics Department, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
4. Department of Math and Statistics, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
5. Program in Atmospheric Sciences, Howard University, Beltsville, MD 20705, USA