Tebatso Moloto, Council for Scientific and Industrial Research (CSIR), Southern Ocean carbon-Climate Observatory (SOCCO), Cape Town, South Africa, Marie Smith, Council for Scientific and Industrial Research, Earth Observation Research Group, Cape Town, South Africa, Thomas George Bell, Plymouth Marine Laboratory, Plymouth, United Kingdom, Stuart Piketh, North-West University, Unit for Environmental Science and Management, Potchefstroom, South Africa and Sandy Jane Thomalla, Council for Scientific and Industrial Research (CSIR), Southern Ocean Carbon and Climate Observatory (SOCCO), Cape Town, South Africa