Hints of ozone layer recovery, scientist says

Larry Twigg and Tom McGee (Nasa), Mike Kotkamp (Niwa, Lauder), Daan  Swart and Anne van Gijsel ...
Larry Twigg and Tom McGee (Nasa), Mike Kotkamp (Niwa, Lauder), Daan Swart and Anne van Gijsel (National Institute for Public Health and the Environment, the Netherlands) Hamish Chisholm (Niwa, Lauder) and Stuart McDermid (Nasa).
Lidar (light detection and ranging) equipment in action on a moonlit night at Lauder. Photos by...
Lidar (light detection and ranging) equipment in action on a moonlit night at Lauder. Photos by Lynda van Kempen and supplied.

There may be a "hint" of recovery in the ozone layer, according to one of the international scientists with equipment based at Lauder for global climate research.

Daan Swart, head of the air quality department at the National Institute for Public Health and the Environment in Holland, has been a regular visitor to the National Institute of Water and Atmospheric Research (Niwa) Lauder station since 1994.

His country built a Lidar (light detection and ranging) system at Lauder that year, as part of a national research programme.

The equipment - "probably worth about $2 million" - remains a valuable tool in climate research.

The Niwa station sits at a perfect spot for southern hemisphere atmospheric research.

"We have some of the cleanest air in the world," Niwa atmospheric processes group manager Paul Johnston said.

Mr Swart, who was one of five international scientists based at the Central Otago site in recent weeks, praised the quality of the data gathered at Lauder.

"It's kind of funny to think that Lauder is such a little township, with only a few people, yet it is famous in scientific circles because of the measurements that can be made here," he said.

Because of the clearness of its skies, it was the site where all the satellites around the world measuring ozone were calibrated, he said.

Measures introduced through the Montreal Protocol on substances that depleted the ozone layer were aimed at the recovery of the layer by 2050.

"The modelling we've done says it will happen and we hope it will - all going according to plan," Mr Swart said.

"There are, maybe, hints of its recovery, although we need to realise that this is a long-term thing."

Most of the measurements taken by Mr Swart and colleague Anne van Gijsel, and those of the US National Aeronautics and Space Administration (Nasa) team of three scientists, who have also been based at Lauder in recent weeks, are done at night.

Lidar equipment sends up laser "pulses" which record the amount of ozone at different heights in the atmosphere.

Sunlight interferes with the readings, so the measurements have to be taken at night.

The Nasa team of Stuart McDermid, Larry Twigg and Tom McGee transported a Lidar housed in a purpose-built trailer to Lauder.

The equipment had been carted all around the world, from the Arctic to Hawaii, France and Germany, Dr McGee said.

Data from the two Lidars was compared and calibrated to ensure they were recording the same measurements.

"There's stringent protocols for these types of things. That's why we have a referee [Dr McDermid]. We take measurements, and they do, and we give them to Stuart, " Dr McGee said.

Lauder is part of the Network for the Detection of Atmospheric Composition Change, a web of more than 70 research stations around the world which monitor global climate change.

- lynda.van.kempen@odt.co.nz

 

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