Project summary

Seasonal climate forecasts made by the Bureau of Meteorology/CSIRO’s coupled ocean/atmosphere model will be tested for skill and value in the context of wheat-based farming systems in southwest Western Australia. The forecasts will be benchmarked against existing forecast systems using several decades of hindcasts. A novel aspect will be the availability of ensemble forecasts which will provide an estimate of forecast reliability. A technique will be developed to reduce a major source of forecast error (coupled model bias) and a new set of hindcasts produced. The skill and value of these hindcasts will be assessed. Both northern and southern cropping regions in WA will be studied, and rainfall skill assessed during the growing season, as well as for early, mid and late periods during the season. The potential economic returns from both sets of forecasts will be evaluated within a SWWA wheat-based farming systems framework in combination with other systems knowledge.

Project objectives

• Improve prediction of early, mid and late growing season rainfall in distinct climate regions in south-west Western Australia relevant to the wheat industry using a global circulation model.
• Establish estimates of forecast uncertainty based on the range of model forecasts, the range of on-farm outcomes, and benchmarking against existing forecast schemes.
• Improve predictability of soil moisture, yield and pasture growth through linking seasonal forecasts to farm practice, soil type and existing information such as stored soil moisture.
• Improve articulation of cereal farm practice options, with potential spin-offs to the grazing industry, based on forecast skill and reliability.
• Establish foundations for ongoing strategic investment in improvement of global circulation models.