Indian Ocean Climate Initiative - Western Australia

Project 3.2: Climate Extremes: Potential Forecast Skill and Climate Change Scenarios (Yun Li, Mark Palmer and Eddy Campbell)

Planned outcomes:

• Develop scenarios for intensity-frequency-duration characteristics of seasonal rainfall under climate change, which can be used for impact and vulnerability assessments.

Figure 3.2.1: Return periods of winter extreme daily rainfall at Manjimup station. Black “o” points represent the empirical return period of winter extreme rainfalls observed in 1930-1965 and red “+” points in 1966-2001. The black and red solid curves represent return period based tail estimates based on fitted generalized Pareto distributions with 95% confidence interval given as black dash lines (1930-1965) and red dot-dashed line (1966-2001). It is evident that the return period of the winter extreme daily rainfall in the post-change period (1966-2001) has greatly increased for the same extreme rainfall levels, which indicates that winter extreme daily rainfall has decreased since 1965.

Figure 3.2.2: Return period of winter extreme rainfall over SWWA between pre-change period 1930-1965 and post-change period 1966-2001 at four stations 9503, 9023, 9591 and 10636. Generally, the return period for winter extreme rainfall of the averaged rainfall series of five stations over SWWA has increased, which implies that extreme rainfall over SWWA has decreased since the change point year 1965.