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12 October 2020 | Story Leonie Bolleurs | Photo Supplied
Adriaan van der Walt
Although several international studies have used temperature metrics to statistically classify their seasonal divisions, a study in which Adriaan van der Walt was involved, would be the first known publication in a South African context using temperature as classification metric.

Gone are the days when we as South Africans would experience a three-month spring season, easing into summer, and then cooling off for three months before we hit winter.

Adriaan van der Walt, Lecturer in the Department of Geography at the University of the Free State (UFS), focuses his research on biometeorology (a specialist discipline exploring the role and climate change in physical and human environments) as well as climatology and geographic information systems.

He recently published an article: ‘Statistical classification of South African seasonal divisions on the basis of daily temperature data’ in the South African Journal of Science.

In this study, which Van der Walt undertook with Jennifer Fitchett, a colleague from the University of the Witwatersrand, data on daily maximum and minimum temperatures was collected from 35 meteorological stations of the South African Weather Service, covering the period between 1980 and 2015.

They went to great lengths to ensure that they had a complete set of data before presenting it to demonstrate seasonal brackets.

First for South Africa

Their statistical seasonal brackets indicate that South Africans now experience longer summers (from October to March), autumn in April and May, winter from June to August, and spring in September.

Although considerable work has been done using rainfall to determine seasonality in Southern Africa, Van der Walt believes that these methods did not work well as there are too many inconsistencies in this approach, as identified by Roffe et al. (2019, South African Geographical Journal). To make matters more complicated – as a semi-arid region, and with desert conditions along the west coast – some regions do not have enough rainfall to use as a classifier.

Temperature, on the other hand, worked well in this study. “Temperature, by contrast, is a continuous variable, and in Southern Africa has sufficient seasonal variation to allow for successful classification,” says Van der Walt.

He continues: “Although several international studies used temperature metrics to statistically classify their seasonal divisions, this study would be the first known publication in a South African context using temperature as classification metric.”

Van der Walt says what we understand as seasons largely relates to phenology – the appearance of blossoms in spring, the colouration and fall of leaves in autumn, and the migration of birds as a few examples. “These phenological shifts are more sensitive to temperature than other climatic variables.”

Seasonal brackets

According to Van der Walt, they believe that a clearly defined and communicated method should be used in defining seasons, rather than just assigning months to seasons.

“One of the most important arguments of our work is that one needs to critically consider breaks in seasons, rather than arbitrarily placing months into seasons, and so we welcome any alternate approaches,” he says.

A number of sectors apply the temperature-based division to their benefit. “For example, in the tourism sector it is becoming increasingly important to align advertising with the season most climatically suitable for tourism,” says Van der Walt.

Temperature-based division is also used to develop adaptive strategies to monitor seasonal changes in temperature under climate change. However, Van der Walt points out that each sector will have its own way of defining seasons. “Seasonal boundaries should nevertheless be clearly communicated with the logic behind them,” he says.

News Archive

Kovsie students selected for prestigious study travel programme
2013-05-15

 

Golden Key International Honour Society members, Michael van Niekerk, Siobhan Canavan, Mpoi Makhetha and Cebolenkosi Sokhela, will travel to the USA and China, meeting the best in their career fields.
Photo: Hannes Pieterse
15 May 2013


They are amongst the top 15 percent of academic achievers at the university, and have been afforded the opportunity to travel abroad and meet with leading people in their fields of study.

Kovsie students Michael van Niekerk, Siobhan Canavan, Mpoi Makhetha and Cebolenkosi Sokhela, all members of the Golden Key International Honour Society, will travel to the USA and China. This trip is part of the International Scholar Laureate Program (ISLP) to learn how their career fields are practiced in another part of the world. The students are part of a select group of outstanding university students from across the world who will be given access to people, places and global perspectives in fields such as business, engineering, medicine, nursing, diplomacy and international relations.

Michael, a fourth-year MBChB student and SRC member of our Bloemfontein Campus, and Cebolenkosi, a third-year BSc Microbiology student will visit Washington, Philadelphia and New York in the USA. As part of the medicine delegation of the programme, they will visit clinics and hospitals to see how their study fields are practiced. Michael’s trip includes a visit to Johns Hopkins University in Baltimore, where he will meet representatives of the National Institute of Health, the largest source of funding for medical research in the world. He will also visit Harvard University in Massachusetts.

Mpoi, a third-year BSc Human Molecular Biology student, also forms part of the medicine delegation but will travel to China. "We will be exploring the ancient ways of healing versus the modern medical practices, exploring the medical systems of the country and meeting doctors and professors, visiting the rural areas, and of course, touring the best parts of China,” she said.

Siobhan, a third-year Media Studies and Journalism student, is part of the diplomacy and international relations delegation who will visit Beijing, Xi'an and Shanghai in China. "To me it's such an honour to be part of this programme,” she said. “It will give me the platform to not only represent who I am, but also my university and the values that the university has instilled in me. It allows me to be a part of something great that will benefit me in the end."

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