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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

Thakaneng bridge: Valentines Promotions

2009-02-13

Thakaneng bridge: Valentines Promotions

Thakaneng bridge: Valentines Promotions - 13 February. Special discount! Prizes to be won!

TRÄUMEREI

Enige twee ontbyte kry `n glasie sap en koffie gratis.
Enige middagete kry `n trammazini of glas huiswyn gratis.

Any two breakfasts get a free juice and coffee.
A free glass of wine or a trammazini with any lunch.

VARSITY INFORMATION & TECHNOLOGY

Spend R1000.00 or more and stand a chance to win an Ipod Shuffle.
More specials in store.

Spandeer R1000.00 of meer en staan `n kans om `n Ipod Shuffle te wen.
Daar sal ook ander spesiale aanbiedinge in die winkel wees.

VETKOEK FACTORY

Heart shaped vetkoek with delicious fillings and get a free heart shaped chocolate with every vetkoek.

Kom geniet `n hartvormige vetkoek met `n smaaklike vulsel en kry `n gratis hartvormige sjokolade.

VARSITY HAIR STUDIO

Make Friday the 13th your lucky day at VARSITY HAIR STUDIO.
Amazing discounts will be given away!

Maak Vrydag die 13de jou gelukkige dag by VARSITY HAIR STUDIO.
Groot afslag op byna alles.

KOVSIE PRIVAAT AKKOMMODASIE

Alle bestaande klante kom neem deel aan `n gelukstrekking en staan `n kans om `n etebewys ter waarde van R400.00 te wen.

All existing clients can enter into a lucky draw and stand a chance to win a free meal worth R400.00.

XEROX

Kom neem deel aan `n “lucky draw” en wen een van verskeie geskenke.
Enter the lucky draw and win one of many prizes.

MELLIN

LEVI, POLO en LUXION-KUKA promosies. Gratis geskenke wannneer `n raam gekoop word.
LEVI, POLO and LUXION-KUKA promotions. A free gift with any frame bought.

8. FRIENDLY SEVEN ELEVEN
Lots of in-store give-aways.
Vele weggee geskenke in die winkel. Besoek ons gerus.

9. RUSH HOUR
Kom prik `n ballon en wen een van vele pryse, waaronder T-hemde, `n koek, teddiebeer of dalk ‘n mini- make over.
Ons maak ook `n plan vir lekker musiek op die brug!

Win a cake, T-shirt ,a teddy bear or a mini make over in our burst a balloon competition.

10.MAMA`S KITCHEN
Kom neem deel aan `n gelukstrekking en wen `n piekniekmandjie vir twee.
`n Gratis geskenkie vir die eerste 100 klante.

Enter the lucky draw and stand a chance to win a picnic hamper for two.
The first 100 clients will receive a gift.

11. ROASTERS
Kom koop een chip twister en kry een gratis.
Buy ` chip twister and get one for free.

12 DIE DELI

Koop een groot ontbyt en kry `n damesontbyt gratis.
Kry skyfies gratis saam met enige burger.

Buy a breakfast and get a ladies breakfast free.
Free chips with any burger.

NASHUA MOBILE

Buy airtime for R10.00 or more and stand a chance to win airtime worth R55.00
Koop lugtyd van R10.00 of meer en staan `n kans om lugtyd ter waarde van R55.00 te wen.

VAN SCHAIK BOEKHANDEL

Alle aankope op 13 Februarie kwalifiseer vir `n gelukstrekking op die 14de Februarie en staan `n kans om `n geskenk te wen waaronder wetenskaplike sakrekenaars, memory sticks en penstelle.

All clients who buy something on 13 February 2009 may enter a lucky draw and may win gifts like pen sets, scientific calculator or a memory stick on 14 February 2009.

ROCKSTARS

Kom koop `n T-hemp en staan `n kans om `n geskenk te wen.

Buy a T-shirt and stand a chance to win a prize

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