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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

UFS council awards honorary doctorates
2007-03-22

The Council of the University of the Free State (UFS) has decided to confer honorary doctorates on architect Prof. Barend Johannes Britz and author Mr Khotso Pieter David Maphalla.

Prof. Bannie Britz is being honoured for his contribution to architecture and Mr Maphalla for his contribution to the development of the Sesotho language and culture.
Prof. Britz worked as an architectural assistant abroad as well as in South Africa between 1961 and 1964, before establishing his own practice in 1968. He obtained a master’s degree in Urban Design in 1991 and was awarded the Prize of the City of Johannesburg for the best urban design dissertation.

He was appointed as Professor and Head of the Department of Architecture at the UFS in 1992. Prof. Britz is a member of several professional associations and has received 17 merit awards as well as a gold medal of excellence from the Institute of SA Architects.

Mr Maphalla is a prolific Sesotho author and has contributed significantly to the development of the Sesotho language and culture through his poetry, novels, dramas and short stories.

Most of his books have been prescribed for secondary schools throughout the country. His collected works are still used as reference works for literary studies by African Languages Departments at most South African universities.

Mr Maphalla played a significant role in the establishment of the South African National Sesotho Authors’ Association and has been the recipient of numerous awards for his sterling work. These include the M-net Book Prize in 1996 and a Lifetime Achiever Award in 2005 from the National Department of Arts and Culture, the first and only Sesotho author to have received this award thus far.

Media release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt.stg@mail.ufs.ac.za
19 March 2007
 

 
Prof. Bannie Britz

 
Mr. Khotso Pieter David Maphalla

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