Australian bushfire smoke cloud continues to circle the earth, one of the largest ever observed

23 April 2020

Published by https://www.stuff.co.nz

AUSTRALIA/GLOBAL – The vast smoke cloud which darkened New Zealand skies in January is continuing its journey around the world.

The Australian bushfire smoke is now 35km above the earth and scientists are still tracking it almost four months later.

Niwa (National Institute of Water and Atmospheric Research) atmospheric scientist Dr Richard Querel said it was remarkable to be able to track a smoke plume for more than 100 days.

“The fires were so energetic they injected smoke and carbon aerosol into the stratosphere, which have since risen to about 35km above the earth.”

At that height in the stratosphere, the smoke cloud is one of the largest plumes of smoke observed by satellites.

Querel said the main bulk of the plume was about five kilometres high and hundreds of kilometres wide.

Scientists have been tracking the smoke since it formed in December, and it has since travelled around the globe several times.

Querel and his colleagues at Niwa’s atmospheric research station at Lauder, Central Otago, were among many scientists across the globe who tracked the smoke travel.

Their measurements have revealed unprecedented ozone loss in the smoke cloud.

Querel said the soot had absorbed the sunlight, heating the smoke cloud as it rose and crossed the Pacific Ocean.

Last week, the cloud was observed over South Africa but had stretched and thinned, Querel said.

“When it reached South America, the blob continued to rise until it entered into the Westerlies and started heading back across the Pacific.”

Earlier this year and last month, the bushfires caused a spike in carbon monoxide readings.

“The important thing about these carbon monoxide readings is that they show just how large these fires were,” Querel said.

However, the carbon monoxide in the stratosphere would have converted to carbon dioxide over a few weeks, and would not be significant for the climate, he said.

The fires covered more than 12 million hectares from September 2019 to February 2020.

In January, Niwa reported Australia’s bushfire smoke travelled like a swirling, braided river towards New Zealand.

Many parts of the South Island were covered in an eerie orange haze and Niwa documented ash deposits on the South Island glaciers originating from the Australian fires.

MetService meteorologist Lewis Ferris said by tracking the cloud’s journey over the Tasman Sea they were able to add “smoky skies”  into their forecasts, so the general public were aware of why the sky was discoloured.

“Decreased daylight intensity and lowered maximum temperatures were common during the most intense events.”

In a similar cloud experience, in 2011 the Puyehue-Cordón Caulle eruption in Chile forced a huge amount of volcanic ash, Ferris said.

“[It] ended up circling the southern hemisphere and making it into New Zealand’s airspace.”

Early last month, the New South Wales Rural Fire Service announced there were no more active bushfires in the state for the first time in more than 240 days.

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