The Impact of Climate Change on the Climatology of Tropical Cyclones in the Australian Region

[摘要] This report presents results from CSIRO's Conformal Cubic Atmospheric Model (CCAM).An analysis of outputs from CCAM downscaled to 65 km grid spacing with NCEP reanalyses shows that the model is able to simulate the spatial characteristics of tropical cyclone (TC) occurrence in the Australian region and that the configuration used for these simulations is able to differentiate between El Niño and La Niña events. However, the modeled frequencies are less than observed with, on average, approximately 60% of the observed number of TCs simulated by CCAM.The underestimate in TC occurrence is most likely due to the relatively coarse grid spacing used in this study.Climate change projections using this modelling system show a strong tendency for a decrease in TC numbers in the Australian region, especially in the region of current preferred occurrence.On average, for the period 2051-2090 relative to 1971-2000, the simulations show an approximately 50% decrease in occurrence for the Australian region, a small decrease (0.3 days) in the duration of a given TC and a southward movement of 100 km in the genesis and decay regions. On average, the southward movement in decay region is greater off the Queensland coast than off the coast of Western Australia.Five of the seven simulations show statistically significant decreases in TC occurrence.A method to apply these projections to specific locations is developed and used to illustrate the importance of using a risk assessment approach when using these projections in the development of management and planning frameworks.Further downscaling of a sample of individual TCs shows a distinct shift towards deeper pressures and a flattening of the maximum wind speed distribution with a larger percentage of TCs producing high wind speeds in the 2070 climate than either the 1980 or 2030 climates.The findings described above are consistent with findings for Southern Hemisphere TC changes from recently published international studies.

[发布日期] 2012-03-15 [发布机构] CSIRO

[学科分类] 地球科学(综合)