It La Niiia has still more rain - University of New South...
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l ' , Forbes golf course is swamped but the town has escaped further inundation. PhotoAAP La Niiia ha s still more ra in The soggy summer is being driven by the interaction between weather patterns. Mark Lawson Householders along the Murray- Darling river sy,stem cleaning mud out of their living rooms will not be pleased to hear that it could all happen again, soon . Parts of the Murray-Darling system could be flooded periodically over the next 20 years or so, depending on the interaction of three climate cycles. Scientists are still arguing over these cycles, including whether one exists at all, and forecasting them is a chancy business. But as far as anyone knows, the cycles are set to bring more rain over the next two years and perhaps over the next two decades. One part of the reason that the skies have opened all summer over parts of NSW is well known. At the moment , the Pacific basin is being ruled by a La Nina, a short-lived climate cycle that includes changes in patterns of sea surface temperatures and winds that result in more rain for eastern Australia. The La Nina cycle is, in turn, part of the El Nino - La Nina Southern Oscillation (ENSO) cycle, which includes both the La Ninas and the reverse climate pattern, the EI Ninos. Bureau of Meteorology records show that this La Nina is now fading fast and is set to disappear over the next few weeks. This La Nina was weaker than the super strong La Nifia of last year that, among other effects, flooded central Brisbane, but there were other factors at play. This La Nina has certainly brought rain enough to flood sections of the Murray-Darling river system as well as bring seemingly endless rain to Sydney. But another, lesser known cycle known as the Southern Annual Mode (SAM) resulted in comparatively dry conditions further south for a time. The SAM index is the difference between the air pressure around the top of Tasmania and the air pressure down near Antarctica. When the index is positive the prevailing weather patterns shift south and conditions are drier. When it is negative, weather patterns shift northwards. This has complex effects but mostly it gets wetter in different places. For much of this summer the SAM has been positive, but it was negative for nart of November (when there was a lot of rain) . Crucially, it also went negative from mid-February until early March, with one result being a lot of sandbag filling in Wagga Wagga in southern NSW. A La Nina combined with a negative SAM means a lot of rain, but it also means rain in different places, notably southern NSW. Milton Speer, a visiting research fellow at the University of NSW's climate change research centre, said the SAM was very difficult to forecast and had proved to be erratic over the past two years. However, it was possible that the index could tend to dip into negative . territory in the next few months, meaning a wetter autumn and winter in south-eastern Australia, he said. The SAM index interacting with the ENSO cycle is one part of the story. But on top of the ENSO cycles sits another cycle known as the Pacific Decadal Oscillation (PDO), or Interdecadal Pacific Oscillation (lPO). This cycle is considerably more stable and longer-term than the others . Characterised by different patterns of sets of sea surface temperatures , the is thought to flip between "warm" and "cool" modes, with quite different patterns for the modes , every 20 to 30 years. When it was in its warm mode, as it was between the mid-1970s and about 2000, there were lots of strong EI Nmos (the reverse of the rain-bearing La Ninas) and apparently endless drought in Australia. Now it has flipped into its cool mode - weakly at first and then strongly from 2007. During that mode the increases the number and severity of La Ninas, while dampening down the El Nmos. The IPO was also in a cool mode during the Brisbane floods of 1974. One group that remains unconvinced about the cycle is the Bureau of Meteorology. Dr Andrew Watkins, manager of climate change prediction at the bureau, said "the jury is still out " on the particularly on the issue of whether changes in the ENSO cycle caused the changes in the or the other way around . In any case, individual events such as the floods in particular areas were the result of a complex interaction between the SAM, ENSO, ocean temperatures, Indian Ocean climate cycles and another effect called the Madden -Julian Oscillation, a pulse of wind and cloud, he said. Wherever these theoretical investigations lead scientists there is little doubt that the climate along Australia's eastern seaboard has changed in a manner quite unexpected by the policymakers who authorised the building of desalinisation plants . ai more rain threatens homes and proP( in NSW's south-west, central west an( suburban Sydney. . More than 1950 houses have been inundated in NSW and the number is expected to rise as floodwater makes way downstream. On Friday, federal Attorney-Genera Nicola Raxon announced funding for flood-affected businesses, primary producers and non-profits in Victoria Victorian Farmers Federation president Andrew Broad said he expected 150 farmers and 300 farmin businesses in Victoria to be affected. j a local level the floodwaters were "hitting records". "It is hard to put a figure on it at thii stage," he said . ... are on Online Auction Opens: Online Auction CJoses: • 28.5m (1 00ft) Higashu Kyusyu Jap • Dual Detroit 12V92TA Engines • Refits Inspect: 74 Seaworld Drive, Main Be, Enquires: Michael Dewhurst on 0423 383 095 Visit www.graysonline.com for furthel www.g Ur Executive Manager, W Unitywater is the water distribution Sunshine Coast regions of South Eas If you thrive in a collaborative envir leadership position in a developing or Resource practices and manage indl could offer your next career move. Experienced in leading teams throL imperative you are a Manager who ur business plan and corporate goals. Reporting to the CEO and part of the for the strategiC leadership and devel Resources strategy and management culture and knowledge workforce. Holding tertiary qualifications, you (generalist) HR role, encompassing inc Management Team wifhin a diverse leading and delivering culture chang will be important. 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Transcript of It La Niiia has still more rain - University of New South...
l
Forbes golf course is swamped but the town has escaped further inundation PhotoAAP
La Niiia has still more rain The soggy summer is being driven by the interaction between weather patterns
Mark Lawson
Householders along the MurrayshyDarling river system cleaning mud out of their living rooms will not be pleased to hear that it could all happen again soon
Parts of the Murray-Darling system could be flooded periodically over the next 20 years or so depending on the interaction of three climate cycles
Scientists are still arguing over these cycles including whether one exists at all and forecasting them is a chancy business But as far as anyone knows the cycles are set to bring more rain over the next two years and perhaps over the next two decades
One part of the reason that the skies have opened all summer over parts of NSW is well known At the moment the Pacific basin is being ruled by a La Nina a short-lived climate cycle that includes changes in patterns of sea surface temperatures and winds that result in more rain for eastern Australia The La Nina cycle is in turn part of the El Nino - La Nina Southern Oscillation (ENSO) cycle which includes both the La Ninas and the reverse climate pattern the EI Ninos Bureau of Meteorology records show that this La Nina is now fading fast and is set to disappear over the next few weeks
This La Nina was weaker than the super strong La Nifia of last year that among other effects flooded central Brisbane but there were other factors at play
This La Nina has certainly brought rain enough to flood sections of the Murray-Darling river system as well as bring seemingly endless rain to
Sydney But another lesser known cycle known as the Southern Annual Mode (SAM) resulted in comparatively dry conditions further south for a time
The SAM index is the difference between the air pressure around the top of Tasmania and the air pressure down near Antarctica When the index is positive the prevailing weather patterns shift south and conditions are drier When it is negative weather patterns shift northwards This has complex effects but mostly it gets wetter in different places
For much of this summer the SAM has been positive but it was negative for nart of
November (when there was a lot of rain) Crucially it also went negative from mid-February until early March with one result being a lot of sandbag filling in Wagga Wagga in southern NSW
A La Nina combined with a negative SAM means a lot of rain but it also means rain in different places notably southern NSW
Milton Speer a visiting research fellow at the University of NSWs climate change research centre said the SAM was very difficult to forecast and had proved to be erratic over the past two years However it was possible that the index could tend to dip into negative territory in the next few months meaning a wetter autumn and winter in south-eastern Australia he said
The SAM index interacting
with the ENSO cycle is one part of the story But on top of the ENSO cycles sits another cycle known as the Pacific Decadal Oscillation (PDO) or Interdecadal Pacific Oscillation (lPO) This cycle is considerably more stable and longer-term than the others Characterised by different patterns of sets of sea surface temperatures the PD~ is thought to flip between warm and cool modes with quite different patterns for the modes every 20 to 30 years
When it was in its warm mode as it was between the mid-1970s and about 2000 there were lots of strong EI Nmos (the reverse of the rain-bearing La Ninas) and apparently endless drought in Australia Now it has flipped into its cool mode shyweakly at first and then strongly from 2007 During that mode the PD~ increases the number and severity of La Ninas while dampening down the El Nmos
The IPO was also in a cool mode during the Brisbane floods of 1974
One group that remains unconvinced about the PD~ cycle is the Bureau of Meteorology Dr Andrew Watkins manager of climate change prediction at the bureau said the jury is still out on the PD~ particularly on the issue of whether changes in the ENSO cycle caused the changes in the PD~ or the other way around
In any case individual events such as the floods in particular areas were the result of a complex interaction between the SAM ENSO ocean temperatures Indian Ocean climate cycles and another effect called the Madden-Julian Oscillation a pulse of wind and cloud he said
Wherever these theoretical investigations lead scientists there is little doubt that the climate along Australias eastern seaboard has changed in a manner quite unexpected by the policymakers who authorised the building of desalinisation plants
ai
more rain threatens homes and proP( in NSWs south-west central west an( suburban Sydney
More than 1950 houses have been inundated in NSW and the number is expected to rise as floodwater makes way downstream
On Friday federal Attorney-Genera Nicola Raxon announced funding for flood-affected businesses primary producers and non-profits in Victoria
Victorian Farmers Federation president Andrew Broad said he expected 150 farmers and 300 farmin businesses in Victoria to be affected j a local level the floodwaters were hitting records
It is hard to put a figure on it at thii stage he said
are on
Online Auction Opens Online Auction CJoses
bull 285m (1 00ft) Higashu Kyusyu Jap bull Dual Detroit 12V92TA Engines bull Refits
Inspect 74 Seaworld Drive Main Be Enquires Michael Dewhurst on 0423 383 095
Visit wwwgraysonlinecom for furthel
wwwg
Ur Executive Manager W
Unitywater is the water distribution Sunshine Coast regions of South Eas
If you thrive in a collaborative envir leadership position in a developing or Resource practices and manage indl could offer your next career move
Experienced in leading teams throL imperative you are a Manager who ur business plan and corporate goals
Reporting to the CEO and part of the for the strategiC leadership and devel Resources strategy and management culture and knowledge workforce
Holding tertiary qualifications you (generalist) HR role encompassing inc Management Team wifhin a diverse leading and delivering culture chang will be important As a member of presentation negotiation and verbal
Applications are to include a two-p qualifications A negotiated executiv
For further information please contac on 07 545 111 08 or petanewstaff
NE SO L
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