LiDAR Network Growing in KZN with UKZN Support

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An article in Business Day recently detailed the launch of a laser spotlight installed at the University of Zululand (UNIZULU) to glean data about the quality of air above the uMhlathuze region and Richards Bay, one of the country’s largest industrial cities characterised by its deep-water harbour, coal terminal and industries processing minerals, paper, fertilisers, aluminium and more.

Researchers at UNIZULU will use the apparatus, built by the Council of Scientific and Industrial Research (CSIR) National Laser Centre (NLC) as part of its efforts to lend equipment and technical support to local universities, to gather new data on aerosol particles, chemicals, water vapour and ice crystals in the clouds. The Department of Science and Technology-funded CSIR NLC also supports postgraduate research projects.

UNIZULU’s Dr Nkanyiso Mbatha, a UKZN alumnus, and the School of Chemistry and Physics’ (SCP) Professor Sivakumar Venkataraman, will lead this work.

The mobile R2.5m atmospheric Light Detection and Ranging (LiDAR) system is utilised to assess parameters related to air pollution, weather and the potential for human-induced climatic change. LiDAR ranges vary, but the present system can extend up to 25 kilometres into the atmosphere. It emits thousands of laser pulses per second to map cloud structure, moisture content and other almost invisible particles, and is similar to technology used by NASA astronomers and traffic police conducting speed trapping. Backscattered signals are then received by telescopes and data is acquired through the use of optical fibre combiners.

The UNIZULU-UKZN team hopes to assess the changes in air quality influenced by the high industrial activity in the region, which could in turn aid local government in monitoring air quality and establishing what environmental impacts these changes could have.

Studies of this nature are important, since South Africa is a large source of human-generated aerosols in the southern hemisphere, yet data is lacking concerning how these aerosols affect the region, particularly with regard to climate. Data in other parts of the world indicate that aerosol emissions influence climate change effects.

The CSIR NLC noted the importance of the addition of this ground-based LiDAR system in Richards Bay as part of an existing network of these systems, which includes fixed and portable LiDARs at UKZN. Based on discussions with Venkataraman, who experienced success with the LiDAR system while working at the CSIR-NLC before joining UKZN, it was decided to deploy the system at UNIZULU.

Its measurements will contribute to efforts of monitoring air pollutant levels in Richards Bay, where concerned residents have noted the negative effects of air pollution. Joint observations between UNIZULU and UKZN will also address the aerosol/pollution transport between their two regions.

UKZN’s LiDAR has been measuring vertical aerosol profiles from three to 25 kilometres in the atmosphere since 2015, having previously operated from 1999-2004 and provided aerosol profiles from three to 35 km, and temperature measurements from 30 to 80 km. The fixed LiDAR system at UKZN is one of three in South Africa, and conducts daily observations for understanding the aerosol and cloud structure over Durban. Aerosol measurements indicate atmospheric pollution levels.

Words: Christine Cuénod 

Photograph: Supplied by CSIR-NLC