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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

Dr Khotso Mokhele joins ranks of distinguished Chancellors

2010-11-21

Attending the inauguration ceremony are, from the left: Mr Pule Makgoe, MEC for Education in the Free State and member of the UFS Council; Judge Ian van der Merwe, Chairperson of the UFS Council; Dr Khotso Mokhele, newly inaugurated Chancellor of the UFS; and Prof. Jonathan Jansen, Vice-Chancellor and Rector of the UFS.
Photo: Dries Myburgh

Dr Khotso Mokhele joined the ranks of distinguished Chancellors of the University of the Free State (UFS) with his inauguration as the new Chancellor of the institution at a ceremony on Friday, 19 November 2010.

The lustrous ceremony took place on the Main Campus in Bloemfontein and was attended by hundreds of guests from all over South Africa.

Dr Mokhele said in his speech: “I am excited to have been invited by the UFS to join its community at the time when it is attempting to reinvent itself into an institution that will be counted amongst those that will shape the local, regional, national will, and by so doing, contribute to the shaping of an African will.”

Dr Mokhele follows in the footsteps of Dr Franklin Sonn, former Ambassador of South Africa in the United States of America and receiver of many awards, acknowledgements, and honorary doctorates, who retired earlier this year. Dr Sonn was preceded by Ms Winkie Direko, former premier of the Free State.

His acceptance of the role of Chancellor is a great honour for the UFS.

According to Prof. Jonathan Jansen, Vice-Chancellor and Rector of the UFS, it is a proud moment to welcome someone from the Province as the Chancellor of this university. With his strong academic values and deep sense of human compassion, Dr Mokhele is one of but a few uncompromising leaders. He is also an inspiring, determined pioneer and a role model to all our students.

Few have done as much to guide the development of science in South Africa since democracy in 1994 as Dr Mokhele. His vision and actions as a senior science manager have been guided by his deep conviction that for a truly democratic society to emerge in South Africa all people must be empowered to be its architects and must have unhindered access to those careers upon which our economy is built.

Dr Khotso Mokhele was born and raised in Bloemfontein. After matriculating from the Moroka High School he went on to study at Fort Hare, where he graduated with a B.Sc. in Agriculture, winning the Massey-Ferguson award for the best student in that field. As a recipient of the prestigious Fulbright-Hays Scholarship, he entered the University of California in Davis where he took a M.Sc. and a Ph.D. degree, both in Microbiology. He was awarded post-doctoral fellowships at the Johns Hopkins University School of Medicine in Baltimore, Maryland, and at the University of Pennsylvania, Philadelphia.

Dr Mokhele returned to South Africa in 1987, set on becoming a top-class academic and researcher. He held lecturing posts at the Universities of Fort Hare (1987-1989) and Cape Town (1990-1992). In 1992 he joined the Foundation for Research Development (FRD) as one of its Vice-Presidents. He succeeded to its presidency in 1996 and then from 1999 to 2006 became the first President of the National Research Foundation (NRF). He successfully merged the FRD and the Centre for Science Development of the Human Sciences Research Council. Under his visionary leadership the NRF has come to play a pivotal role in the development agenda of the country. He was also instrumental in the establishment of the South African Academy of Sciences serving as its founder president (1996-1998).

Dr Khotso Mokhele's contribution to science in South Africa has received wide recognition locally and abroad. He has received nine honorary doctorates. He was made a Chevalier of the Legion of Honour by the President of France in recognition of his personal efforts in strengthening scientific ties between France and South Africa, and was appointed a director of the Salzburg Seminar, an institution focused on global change, and subsequently a member of its Council of Senior Fellows.

He also serves on the boards of major companies such as Implats, Adcock Ingram and Afrox.

Complete speech (Pdf)

Media Release
Issued by: Lacea Loader
Director: Strategic Communication (actg)
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl@ufs.ac.za19 November 2010

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