Defeating the Autumn predictability barrier : SRDC Final report JCU027

Abstract

The success of an Australian sugarcane cropping season depends on rainfall and the ability to forecast it. The benefits associated with long range rainfall forecasts to reduce the risk and uncertainty associated with decisions impacted by rainfall variability has become increasingly recognized by industry. There are several crucial decisions that must be finalised by March and are severely effected by climate conditions during September to November. These types of decisions had to be made without the aid of climate forecasting technologies owing to the autumn predictability barrier, or, more formally, the austral autumn persistence barrier. Around March, April and May traditional rainfall indicators like the southern oscillation index (SOI) and the Niño 3.4 index are unable to reliably forecast across the autumn time zone. To help industry improve preparation for the season ahead, a forecasting system that could provide reliable forecasts about end of season rainfall, early in the year, was needed.

Industry makes many decisions at the beginning of the year (e.g. January to March) that are heavily affected by harvest rainfall. Decisions such as when to start the harvest season have an enormous impact on industry profitability (refer Figure 1). Prior to JCU027, industry had no access to climate forecasting technologies that would assist with these types of decisions owing to the austral persistence barrier. Project JCU027 has overcome this severe limitation and described and tested an approach that allows industry to consult climate forecasts when considering harvest and mill start dates, and planning harvesting scheduling strategies.