Student braves wintry hell to check ozone hole gases

By SIMON COLLINS science reporter

A 23-year-old student has braved temperatures of -40C to take the first winter measurements of gases which interact to form the dangerous ozone hole over Antarctica.

Rebecca Batchelor, a Canterbury University doctoral student, is one of four women and 11 men who have spent the winter in constant darkness at New Zealand's southernmost outpost, Scott Base.

Relief is due today when the first flight from New Zealand since March should arrive, coinciding with the first spring sunrise.

The sun was actually due to rise on Tuesday but by yesterday was still hidden by clouds.

It is the first time in almost 10 years that three scientists, including Ms Batchelor, have wintered over at Scott Base with the usual support crew of 12 who keep automated experiments ticking over in normal years.

Her measurements of hydrogen chloride and nitric acid in the stratosphere have never been taken in an Antarctic winter before because they need a light source for the instruments.

With no sun through the winter, she used moonlight instead.

"When the moon is clear, I go up to Arrival Heights, which is an 8km drive up on the hill above McMurdo and Scott Base.

"We've got a lab up there, where my instruments are," she told the Herald from Scott Base yesterday.

"During the full moon time, I'm working up there a lot.

"I'll take measurements for several hours if the weather stays good. It's really weather-dependent.

"Usually I'm up there by myself, but the science technician has other experiments running up there that she keeps an eye on."

She has tracked the slow formation of a thick cloud over Antarctica which forms every winter. "In the winter time there's a polar vortex in which very, very fast winds go round and round Antarctica and stop the air mixing with air from the rest of the world, so the air gets very cold and a special aqueous cloud forms," she said.

"On those clouds, hydrogen chloride and chlorine nitrate are able to react and release chlorine so it can go and eat ozone molecules when the sun hits it."

The chlorine molecules - originally released into the atmosphere from spray cans and other human activities in cities thousands of kilometres away - react with ozone, effectively extracting the ozone out of the upper atmosphere and opening a "hole" through which dangerous ultra-violet radiation can get through to the Earth.

Apart from unusual weather last summer, the ozone hole has persisted for 25 years and scientists believe it will be another 50 years before it disappears, despite an international agreement in 1987 to phase out the chlorofluorocarbons used in spray cans and fridges which were the main source of chlorine in the air.

Until now, scientists have had to theorise about how the ozone hole forms. Now Rebecca Batchelor's work is producing the gas measurements to prove it.

She has been in Antarctica since January and will not leave until October. But she and her 14 colleagues at Scott Base were not getting on one another's nerves.

"There have been no big disagreements. We just get on really well and have a great time," she said.

"It's lucky, because it would be horrible to be stuck here for 10 months with people you didn't get on with."

She was coping with the -40C temperatures.

"You just accept it and deal with it," she said. "Your life revolves a lot more around the weather than it would at home.

"There are days when you really can't go outside, and there are other days when minus 40 is nothing because there's no wind.

"The darkness hasn't been so bad. I thought that would get me, but with the full moon it's really bright.

"We've had some fantastic auroras, and the stars are always incredible here.

"I would give anything not to have missed out on it. It's been terrific."

How the holes form

* Spray cans and other devices release chlorine into the Earth's atmosphere.

* Very cold air in Antarctica forms a watery cloud, which in turn sets off a chemical reaction between hydrogen chloride and chlorine nitrate.

* This reaction releases the chlorine, which "eats" ozone molecules, creating the hole in the ozone layer.

Total Ozone Mapping Spectrometer

National Institute of Water & Atmospheric Research