Sudden warming over Antarctica to prolong Australia drought
Sydney (AFP) –
A rare phenomenon causing "the strongest Antarctic warming on record" is set to deliver more pain to dought-stricken Australia, scientists said Friday.
The unusual event, known as "sudden stratospheric warming", started in the last week of August when the atmosphere above Antarctica began heating rapidly, scientists at Australia's Bureau of Meteorology said in a report.
"The Bureau of Meteorology is predicting the strongest Antarctic warming on record, likely to exceed the previous record of September 2002," it said.
The upper atmosphere above the South Pole has heated up from close to minus 70 to about minus 25 degrees Celsius, bureau climatologist Andrew Watkins told AFP.
"It has leapt up more than 40 degrees warmer than normal in the course of three weeks," he said.
Watkins said the uncommon occurrence was not believed to be linked to global warming.
The occurrence is triggered by a mix of "disturbances" in weather patterns closer to the ground, he added.
Sudden stratospheric warming is common in the northern hemisphere but has only been recorded on one other occasion, in 2002, in the southern hemisphere.
"It can warm quite rapidly if it gets the right influences, or right pulses, from down below caused by big weather systems at the surface or air hitting mountain ranges a certain way," Watkins said.
The rapid warming slows down westerly winds spinning in the upper atmosphere above the South Pole until they move to the surface.
The winds track northwards until they are over Australia, blowing eastwards across the dry centre to New South Wales and Queensland states, which are currently struggling through one of the driest periods on record.
"You start getting more winds from central Australia, from the desert and less winds from the ocean, so they tend to have drier, warmer conditions in New South Wales and Southern Queensland," Watkins said.
The impacts of the Antarctic event in Australia will start to arrive in the coming weeks, and be particularly felt in October before the weather pattern is expected to break down in December or January.
The east of Australia has been battling hundreds of bushfires in recent weeks, in an unusually early start to the season.
© 2019 AFP