ANALYSIS of complex weather data and the interactions between phenomena such as La Nina / El Nino and the Southern Annular Mode have led researchers at Flinders University in Adelaide to make what could be breakthrough in forecasting.
The team at the National Centre for Groundwater Research and Training (NCGRT) at Flinders believes there is a formula that can be successfully used to predict strong weather events, either dry or wet, several months in advance.
At present medium term forecasts are not useful until the season has already begun and croppers have generally spent the bulk of their budget, so something that could allow more decisions to be made earlier in the season, potentially saving money in dry years and maximising returns in better seasons would be invaluable.
Lead researcher Huade Guan, associate professor in hydrology said the model, said the formula had successfully been used to retrospectively predict the 1988 and 1999 droughts in South Australia.
"There is good promise with the formula in the work we have done modelling South Australia," Ass Prof Guan said.
He said that while South Australia had been the focus of the research thus far he hoped to look into whether the system had any merit for long term forecasting in other parts of the country.
The system is based on using sea temperatures and key climate drivers to predict outcomes.
Over more than a decade Flinders researchers evaluated the impacts of sea surface temperature variations in southern hemisphere oceans on rainfall in South Australia.
They found a seven-year lead ocean-atmosphere oscillation for precipitation patterns which can be used to help make more accurate predictions.
Ass Prof Guan said the major driver of the links was not the El Nino / Southern Oscillation in the Pacific Ocean or the Indian Ocean Dipole but rather the lesser known Southern Annular Mode.
However, he said there was a caveat for those expecting to know the season seven years out.
"We have only had accurate results when there is a positive phase of Interdecadal Pacific Oscillation (IPO), another climate driver, we are not sure why this is the case as yet, but it shows there is still a lot of research to go."
He said the team was now looking for the next phase of the IPO, a slow changing phenomenon, to further refine their theory.
In terms of the research that found the links, it is a highly complicated process.
"We filled the teleconnection with a 27-season lag correlation between sea surface temperature off the coast of South Australia and the Southern Annual Mode, and a two-season lag correlation between rainfall in SA and sea surface temperature," Ass Prof Guan said.
Other co-authors Wenju Cai (CSIRO and Flinders alumnus) and previous visiting scholars Lingli Fan and Jianjun Xu (Guangdong Ocean University) confirmed this connection was dominant between 1979-1998, when the Pacific Ocean was in a positive phase of the IPO.
"Focusing on this period, we were able to delineate an oceanic pathway showing how sea water temperature anomaly associated with the South Annual Mode propagated from the southern Pacific Ocean to South Australian seas in about 27 seasons," Ass Prof Guan said.