HR: 14:10h
AN: GC13B-03    [Abstracts]
TI: Assessing trends in observed and modelled climate extremes over Australia in relation to future projections
AU: * Alexander, L V
EM: Lisa.Alexander@arts.monash.edu.au
AF: Monash University, School of Geography and Environmental Science Building 11 Wellington Road, Clayton, VIC 3800, Australia
AU: * Alexander, L V
EM: Lisa.Alexander@arts.monash.edu.au
AF: Met Office, Hadley Centre, Fitzroy Road, Exeter, EX1 3PB, United Kingdom
AU: Arblaster, J M
EM: J.Arblaster@bom.gov.au
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, United States
AU: Arblaster, J M
EM: J.Arblaster@bom.gov.au
AF: Bureau of Meteorology Research Centre, GPO Box 1289, Melbourne, VIC 3001, Australia
AU: Arblaster, J M
EM: J.Arblaster@bom.gov.au
AF: University of Melbourne, Department of Earth Sciences McCoy Building, Melbourne, VIC 3010, Australia
AB: Multiple simulations from nine global coupled climate models were assessed for their ability to reproduce observed trends in a set of indices representing temperature and precipitation extremes over Australia. Observed trends over the 1957 to 1999 period were compared with individual and multi-modelled trends calculated over the same period. When averaged across Australia the magnitude of trends and interannual variability of temperature extremes were well simulated by most models particularly for the warm nights index. The majority of models also reproduced the correct sign of trend for precipitation extremes although there was much more variation between the individual model runs. A bootstrapping technique was used to calculate uncertainty estimates and also to verify that most model runs produce plausible trends when averaged over Australia. Although very few showed significant skill at reproducing the observed spatial pattern of trends, a pattern correlation measure showed that spatial noise could not be ruled out as dominating these patterns. Two of the models with output from different forcings showed that the observed trends over Australia for some of the temperature indices were consistent with an anthropogenic response but were inconsistent with natural-only forcings. Future projected changes in extremes using three emissions scenarios were also analysed. Australia shows a shift towards warming of temperature extremes particularly a significant increase in the number of warm nights and heat waves with much longer dry spells interspersed with periods of increased extreme precipitation irrespective of the scenario used.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1626 Global climate models (3337, 4928)
DE: 1637 Regional climate change
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting