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SA now experiencing half-year summers

12 October 2020 | Story Leonie Bolleurs | Photo Supplied

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 unanimously reappoints Dr Khotso Mokhele as Chancellor

2015-04-02

Dr Khotso Mokhele, Chancellor of the University of the Free State

The Council of the University of the Free State (UFS) unanimously reappointed Dr Khotso Mokhele as Chancellor during its quarterly meeting held on 13 March 2015. He was first appointed in this portfolio by the Council on 4 June 2010.

“It is an honour for the Council to reappoint someone of this stature as Chancellor of the UFS. With his solid academic background and high profile in the business world, Dr Mokhele has been a great asset to the UFS. On behalf of the Council and the university community, I extend a word of appreciation for the work he has done during his first term as Chancellor of the UFS. He is an exceptional leader, and the university community is looking forward to have him as Chancellor for a second term,” said Judge Ian van der Merwe, Chairperson of the UFS Council.

Dr Mokhele was awarded a BSc Agriculture from Fort Hare University, and continued his studies at the University of California Davis (USA) on the Fulbright-Hays Scholarship Programme, completing his MSc (Food Science) and PhD (Microbiology). He was subsequently a postdoctoral fellow at Johns Hopkins University School of Medicine (USA) and the University of Pennsylvania School of Medicine (USA). Dr Mokhele is the recipient of honorary doctorates from nine South African universities including the UFS, and from Rutgers University in the USA.

He was Chairman of the Rhodes Scholarship Selection Committee for Botswana, Malawi, Namibia, Lesotho and Swaziland (2007-2011), and served on the South Africa at Large Rhodes Scholarship Selection Committee for more than 10 years. As President and Chief Executive Officer (CEO) of the Foundation for Research Development (1996-1999) and the NRF from 1999 to 2006, Dr Mokhele played a central role in providing visionary and strategic direction to the South African science system. He was the Founder President of the Academy of Science of South Africa (ASSAf), Founder President and CEO of the National Research Foundation (NRF), Chairperson of the Economic Advisory Council to the Premier of the Free State (2001-2004), and a member of the Advisory Council on Innovation to the Minister of Science and Technology (2003-2007). His role in securing government and international support for the Southern African Large Telescope Project (SALT) is evidence of his dedication to science in South Africa. The success of this project laid the basis for South Africa being selected to host more than 70% of the Square Kilometre Array, an international mega telescope for radio astronomy.

In recognition of his contribution to the development of science, he was the recipient of the Technology Top 100 Lifetime Achievers Award in 2009 and the National Science and Technology Forum Award in 2005. His role in science is recognised internationally. He was an elected Vice-President: Scientific Planning and Review of the International Council for Science and Chairperson of its Committee for Scientific Planning and Review (2005-2008) as well as a member of the Committee on Developing and Transition Economy Countries of the International Social Science Council (2008-2010). He also represented South Africa on the executive board of UNESCO, and was awarded the Member Legion of Honour of the Republic of France for his work in strengthening scientific ties between South Africa and France.

Dr Mokhele currently serves as Special Advisor to the Minister of Science and Technology, the Honourable Naledi Pandor. His current corporate positions include: Non-Executive Chairman: Board of Directors, Impala Platinum Holdings Ltd (Implats); Lead Independent Non-Executive Director: African Oxygen Ltd (Afrox); Non-Executive Director of Zimbabwe Platinum Holdings Ltd (Zimplats); Hans Merensky Holdings Ltd; and Tiger Brands Ltd. He is the President of the Hans Merensky Foundation (South Africa) and a Trustee of SciDev.Net (a web-based scientific magazine based in London, UK) and Start International Inc (USA).

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