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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

Eye tracker device a first in Africa

2013-07-31

31 July 2013

Keeping an eye on empowerment

"If we can see what you see, we can think what you think."

Eye-tracking used to be one of those fabulous science-fiction inventions, along with Superman-like bionic ability. Could you really use the movement of your eyes to read people's minds? Or drive your car? Or transfix your enemy with a laser-beam?

Well, actually, yes, you can (apart, perhaps, from the laser beam… ). An eye tracker is not something from science fiction; it actually exists, and is widely used around the world for a number of purposes.

Simply put, an eye tracker is a device for measuring eye positions and eye movement. Its most obvious use is in marketing, to find out what people are looking at (when they see an advertisement, for instance, or when they are wandering along a supermarket aisle). The eye tracker measures where people look first, what attracts their attention, and what they look at the longest. It is used extensively in developed countries to predict consumer behaviour, based on what – literally – catches the eye.

On a more serious level, psychologists, therapists and educators can also use this device for a number of applications, such as analysis and education. And – most excitingly – eye tracking can be used by disabled people to use a computer and thereby operate a number of devices and machines. Impaired or disabled people can use eye tracking to get a whole new lease on life.

In South Africa and other developing countries, however, eye tracking is not widely used. Even though off-the-shelf webcams and open-source software can be obtained extremely cheaply, they are complex to use and the quality cannot be guaranteed. Specialist high-quality eye-tracking devices have to be imported, and they are extremely expensive – or rather – they used to be. Not anymore.

The Department of Computer Science and Informatics (CSI) at the University of the Free State has succeeded in developing a high-quality eye tracker at a fraction of the cost of the imported devices. Along with the hardware, the department has also developed specialised software for a number of applications. These would be useful for graphic designers, marketers, analysts, cognitive psychologists, language specialists, ophthalmologists, radiographers, occupational and speech therapists, and people with disabilities. In the not-too-distant future, even fleet owners and drivers would be able to use this technology.

"The research team at CSI has many years of eye-tracking experience," says team leader Prof Pieter Blignaut, "both with the technical aspect as well as the practical aspect. We also provide a multi-dimensional service to clients that includes the equipment, training and support. We even provide feedback to users.

"We have a basic desktop model available that can be used for research, and can be adapted so that people can interact with a computer. It will be possible in future to design a device that would be able to operate a wheelchair. We are working on a model incorporated into a pair of glasses which will provide gaze analysis for people in their natural surroundings, for instance when driving a vehicle.

"Up till now, the imported models have been too expensive," he continues. "But with our system, the technology is now within reach for anyone who needs it. This could lead to economic expansion and job creation."

The University of the Free State is the first manufacturer of eye-tracking devices in Africa, and Blignaut hopes that the project will contribute to nation-building and empowerment.

"The biggest advantage is that we now have a local manufacturer providing a quality product with local training and support."

In an eye-tracking device, a tiny infra-red light shines on the eye and causes a reflection which is picked up by a high-resolution camera. Every eye movement causes a change in the reflection, which is then mapped. Infra-red light is not harmful to the eye and is not even noticed. Eye movement is then completely natural.

Based on eye movements, a researcher can study cognitive patterns, driver behaviour, attention spans, even thinking patterns. A disabled person could use their eye-movements to interact with a computer, with future technology (still in development) that would enable that computer to control a wheelchair or operate machinery.

The UFS recently initiated the foundation of an eye-tracking interest group for South Africa (ETSA) and sponsor a biennial-eye tracking conference. Their website can be found at www.eyetrackingsa.co.za.

“Eye tracking is an amazing tool for empowerment and development in Africa, “ says Blignaut, “but it is not used as much as it should be, because it is seen as too expensive. We are trying to bring this technology within the reach of anyone and everyone who needs it.”

Issued by: Lacea Loader
Director: Strategic Communication

Telephone: +27 (0) 51 401 2584
Cell: +27 (0) 83 645 2454
E-mail: news@ufs.ac.za
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