It’s Official – The Bureau Declares El Niño and Positive Indian Ocean Dipole Events
By: Steff Willis
The Bureau of Meteorology has declared that El?Niño and a positive Indian Ocean Dipole (IOD) are underway, the first time this has occured since 2015.
Bureau of Meteorology Climate Manager Dr Karl Braganza said both El Niño and a positive Indian Ocean Dipole tend to draw rain away from Australia.
“Over spring, their combined impact can increase the chance of below average rainfall over much of the continent and higher temperatures across the southern two-thirds of the country,” Dr Braganza said.
“The Bureau’s three-month forecast for Australian rainfall and temperature has been indicating warm and dry conditions for some time.”
“An established El Niño and positive IOD reinforces our confidence in those predictions. Based on history, it is now also more likely that warm and dry conditions will persist over eastern Australia until autumn.”
El Niño events increase the risk of extreme temperature shifts, like heatwaves and hotter days.
Channel 7’s meteorologist Tony Auden spoke about the recent heatwave impacting the Eastern States.
“The numbers we’re looking at… it’s reasonably high. We’re seeing the global climate’s been very warm this year and we’re expecting some much higher numbers than we’ve seen the last couple of years with El Niño on our doorstep.” Tony Auden said.
“It will probably be a lot hotter and dryer than what we’ve had and it’s the time of year where we start to get those one or two days that really start to spike.”
Increased fire danger in south-eastern Australia is associated with El Niño conditions. A positive IOD contributes to greater fire risk over southeast Australia in spring, while El Niño contributes to elevated fire risk over both spring and summer.
The Bureau made the El Niño declaration after three of the four El Niño criteria were met, including a sustained response in the atmospheric circulation above the tropical Pacific.
The last time Australia encountered both El Niño and a positive IOD was in 2015.
“Around two-thirds of Australia’s driest years on record were during El Niño however, no two El Niño or IOD events or their impacts are the same,” Dr Braganza said.
“El Niño is part of a natural climate cycle that affects global weather and occurs on average every three to five years.” Bureau of Meteorology Climate Manager Dr Karl Braganza
Bureau Senior Climatologist Catherine Ganter said the Indian Ocean Dipole can have as large an influence on Australia’s rainfall and temperature as El Niño.
“A positive IOD often results in below average rainfall during spring for much of central and southern Australia and warmer than average maximum temperatures for the southern two-thirds of Australia,” Ms Ganter said.
“Similar to El Niño, the IOD describes a natural climate cycle brought about by sustained changes in the difference between sea surface temperatures in the tropical western and eastern Indian Ocean.”
Since 1960, when reliable records began for the IOD, there have been around 16 positive IOD and 15 El Niño years. Seven years have seen positive IOD and El Niño events happen at the same time.
Article supplied with thanks to 96five.
