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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

UV vestig hom afgelope eeu as leier op verskeie terreine
2004-05-11

Michelle O'Connor - Volksblad - 11 Mei 2004

Ondank terugslae nou 'n 'gesonde volwassene'

HOEWEL die Universiteit van die Vrystaat (UV) vanjaar sy eeufees vier en met 23 000 studente die grootste universiteit in die sentrale deel van die land is, was dié instelling se geboorte glad nie maklik nie. MICHELÉ O'CONNOR het met prof. Frederick Fourie, rektor, oor die nederige begin van dié instelling gesels.

DIE behoefte aan 'n eie universiteit in die Vrystaat het reeds in 1855, kort ná die stigting van Grey-kollege, kop uitgesteek.

Grey se manne het hulleself teen 1890 begin voorberei om die intermediêre B.A.-eksamens af te lê. Dié eksamen het hulle toegang gegee tot die tweede jaar van 'n B.A.-graad aan die destydse University of the Cape Good Hope, nou die Universiteit van Kaapstad.

"Presidente F.W. Reitz en M.T. Steyn het destyds albei die stigting van 'n universiteit hier bepleit. Die grootste rede was sodat die seuns van die Vrystaat nie weggestuur word nie.

"Dié twee se droom is op 28 Januarie 1904 bewaarheid toe ses studente hulle onder dr. Johannes Bril, as hoof/rektor van Grey-kollege, vir die graad B.A. ingeskryf het. Dié graad is aanvanklik deur die Kaapse universiteit toegeken.

"Net die klassieke tale soos Latyns en Grieks, die moderne tale, Nederlands, Duits en Engels, filosofie, geskiedenis, wiskunde, fisika, chemie, plant- en dierkunde is aanvanklik aangebied.

"Die UV se geboue het gegroei van 'n klein tweevertrek-geboutjie wat nou naby Huis Abraham Fischer staan, en verblyf in die Grey-kollege se seunskoshuis," sê Fourie.

Volgens hom is die universiteit se eerste raad en senaat tussen 1904 en 1920 saamgestel. Die eerste dosente is aangestel en die eerste geboue opgerig. "Dié tyd was egter baie moeilik.

"Die instelling het teen 1920 net 100 studente gehad en was geldelik in die knyp. Daar was geen vaste rektor nie en geen vooruitgang nie. Vrystaatse kinders is steeds na ander universiteite gestuur.

"Ds. J.D. Kestell, rektor van 1920 tot 1927, het egter dié instelling finaal gevestig.

"Hy het self studente van oor die hele Vrystaat gewerf en geld by onder meer kerke en banke ingesamel. Kestell het selfs Engelse ouers oortuig om hul kinders na die Greyuniversiteitskollege (GUK) te stuur en teen 1927 het dié instelling met 400 studente gespog.

"In die tydperk tussen 1927 en 1950 het die GUK weer verskeie terugslae beleef.

"In dié tyd was dit onder meer die Groot Depressie en die Tweede Wêreldoorlog. Die armblanke-vraagstuk het regstreeks op studente en dosente ingewerk en die politieke onderstrominge van dié tyd het die instelling ontwrig.

"Die GUK het egter oorleef en die Universiteitskollege van die Oranje-Vrystaat (UKOVS) is in 1935 gebore," sê Fourie.

Hy sê in dié tyd is verskeie fakulteite gevestig en teen 1950 het die UKOVS met 1 000 studente gespog.

Teen 1950 het dit 'n onafhanklike universiteit geword en die naam is verander na die Universiteit van die OranjeVrystaat (UOVS).

Dié tydperk is gekenmerk deur Afrikaner- en blanke selfvertroue en heerskappy. Studentegetalle het tot 7 000 in 1975 gegroei en heelwat vooruitgang het in dié tyd plaasgevind.

"Tussen 1976 en 1989 sukkel dieuniversiteit weer met onder meer ekonomiese krisisse, die land se politieke onstabiliteit en word die UOVS geï soleer.

"Een ligpunt in dié tyd is die toelating van die eerste swart studente, die nuwe Sasol-biblioteek en die fakulteit teologie wat die lig sien.

"Tussen 1990 en vanjaar het die UOVS verskeie op- en afdraandes beleef. Die universiteit doen nie net die eerste stappe van transformasie nie, maar begin ook aan 'n beleid van multikulturaliteit werk.

"Die UOVS se naam verander in 1996 na die Universiteit van die Vrystaat/University of the Free State en in 2001 word die Sotho-vertaling bygevoeg.

"Geldelike druk en probleme neem drasties toe en personeel word gerasionaliseer.

"Teen 2000 begin die UV met 'n draaistrategie en studentegetalle neem tot meer as 23 000 toe," sê Fourie.

Hy sê die UV het die afgelope eeu nie net verskeie terugslae oorleef nie, maar homself ook op verskeie gebiede as 'n leier gevestig.

Die universiteit behaal sy eie geldelike mikpunte, neem 'n nuwe taalbeleid van veeltaligheid aan en herbelê in personeel.

Die instelling inkorporeer die kampusse van die Vista- en Qwaqwa-universiteit en groei internasionaal.

Die UV vestig ook fondamente van 'n institusionele kultuur van verdraagsaamheid, geregtigheid en diversiteit.

"Die baba het in die afgelope eeu 'n gesonde volwassene geword."

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