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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

A Kovsie friend in need is a Kovsie friend indeed
2015-09-23


Several student organisations have recently started
initiatives to lessen the burden on needy students,
and on the broader community. It is because of
these initiatives that donations of food, commodities
and clothes reached the No Student Hungry (NSH)
Bursary Programme at the University of the Free State.

Photo: René-Jean van der Berg

Kovsie students have often showed that a friend in need is a friend indeed. Several student organisations have recently started initiatives to lessen the burden on needy students, and on the broader community.

It is because of these initiatives that donations of food, commodities and clothes reached the No Student Hungry (NSH) Bursary Programme at the University of the Free State.

The Rag Community Service and NSH offices are extremely grateful to students and staff for their selfless donations, also in respect of the difference these initiatives are making to Kovsies’ chances of having a better future.

The food and commodities will be distributed to the community, while the clothing donations are used for regular clothing sales in order to raise funds.

The food donations included a substantial donation from the support organisation, Gift of the Givers. The organisation heard about the NSH Bursary Programme and, due to the scope of the student-hunger problem, decided to become involved.

“This is an excellent initiative, and the passion with which it is driven motivated us to make a donation,” said Ms Emily Thomas, representative from Gift of the Givers.

Ms Karen Scheepers, Assistant-Director: Student Life responsible for Rag Community Service, said the recent donations and initiatives are proof that the Kovsie community really cares for each other.

“I found it amazing how willing students were to help and to give. From the moment we asked for help, students arrived at our offices with loads of stuff.”

 

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