Encouraging advances in seasonal predictions of drought are being made using powerful computer-based models of the world's climate.

This is the message from Dr Malcolm McIntosh, Chief Executive of CSIRO, who this morning launched a new book and CD-ROM on Australia's climatic variability at the Second Australian Conference on Agricultural Meteorology at the University of Queensland in Brisbane.

El Nino - Southern Oscillation & Climatic Variability describes every major El Nino and La Nina event since 1871.

It is the El Nino reversals in normal Pacific ocean currents and winds that so often bring ravaging droughts to Australia. La Nina is the opposite phase of El Nino, often bringing heavy rainfall to Australia.

The new publication contains more than 90 million ocean temperature and air pressure measurements from around the world, which have been animated to show the waxing and waning of El Nino.

"Climate researchers will now have at their fingertips an invaluable dataset," said CSIRO's Dr Rob Allan, one of the authors. "We are using the data in the publication to evaluate how well we can simulate the droughts we have had in the past," said Dr Allan.

El Nino events are the cause of widespread drought over northern and eastern Australia. The recent harsh drought, which persisted from mid-1990 to mid-1995, was caused by one of the longest sequences of El Ninos on record. The severe drought in 1982-83 was also due to El Nino.

Other authors of El Nino - Southern Oscillation & Climatic Variability are Dr Janette Lindesay from the Australian National University and Mr David Parker from the United Kingdom Meteorological Office.

The Land and Water Resources Research and Development Corporation assisted with production of the publication.

More information from: Dr Chris Mitchell 015 322 519, chris.mitchell@dar.csiro.au