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Fiona Johnson receiving best student presentation award from MSSANZ president Professor Tony Jakeman

Year 3 PhD student Fiona Johnson was awarded a best student presentation award at the Modelling and Simulation Society of Australia and New Zealand (MSSANZ) 2009 conference in Cairns in July. Fiona’s award was based on the following two papers:

Johnson, F. and A. Sharma, 2009: GCM simulations of a future climate: How does the skill of GCM precipitation simulations compare to temperature simulations. 18th IMACS World Congress and MODSIM09, Cairns, Australia, Modelling and Simulation Society of Australia, 199:1-6.

——, 2009: Assessing future droughts in Australia - a nesting model to correct for long-term persistence in general circulation model precipitation simulations. 18th IMACS World Congress and MODSIM09, Cairns, Australia, Modelling and Simulation Society of Australia, 297:1-6.

The first of the two papers presented a measure of skill with which General Circulation Models (GCMs) simulate the future climate. The skill score, which ranges from 0 to 100 as skill increases, has high values for variables such as surface pressure and temperature (skill in the range of 80-90/100), but low values for rainfall (skill = 7/100). This points to one of the key problems associated with model simulations for a future climate – there is little agreement between different models when simulating variables of interest to water resources management decision makers.

The second paper presented a GCM post-processor for imparting long-term persistence to simulated rainfall,  to better model features such as droughts and extended wet spells. The paper assessed the extent of drought that is simulated across Australia for the year 2080, and found that while there is an eight-fold increase in the frequency of extreme drought because of climate change across Australia (under an A2 CO₂ emission scenario using the CSIRO Mk3.5 GCM), the use of the post-processor leads to a 15% reduction in the area that is likely to experience extreme drought across the country.

Fiona’s research is supported by an Australian Postgraduate Award – Industry (APA-I) funded by the Australian Research Council and Sydney Catchment Authority.

For more details, please contact Fiona Johnson (fiona.johnsonroberto@student.unsw.edujlo.au) or Ashish Sharma (a.sharmaroberto@unsw.edujlo.au).