From [URBNRM] Network Update 22nd July 2006
The Southern Oscillation, the weather phenomenon with El Niño and La Niña episodes linked to climate in eastern Australia, is relatively well known. However, the Southern Oscillation is not our only significant weather oscillation. The “Pacific Decadal Oscillation” (PDO) is long lived Southern Oscillation-like pattern of Pacific climate variability. While the two climate oscillations have similar spatial climate fingerprints, they have very different behavior in time. Southern Oscillation events typically persist for only up to several years, whereas PDO events persist for 20-30 years. Interestingly, it has been found that the PDO had featured most strongly than at least some parts of south-eastern Australia.
Independent studies find evidence for just two full PDO cycles in the past century: ‘cool’ PDO events prevailed form 1890-1924 and again from 1947-1976, while ‘warm’ PDO events dominated from 1925-1946 and from 1977 through to at least the mid-1990’s. The 1947-1976 ‘cool’ event appears to be associated with wetter decades in eastern Australia, and the ‘warm’ events since 1977 associated with relatively dry decades. The 1947-1976 wetter decades are the time that many Australians remember as “the normal wet season we use to have”, and also the time when much of our urban water supply dam infrastructure was planned or constructed.
For Further information visit http://jisao.washington.edu/pdo/ and http://www.grdc.com.au/growers/res_upd/south/s04/ridge.htm
