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CMIP5 Decadal Hindcasts of Australian Precipitation Conditions

Paper Reviewed
Mehrotra, R, Sharma, A., Bari, M., Tuteja, N. and Amirthanathan, G. 2014. An assessment of CMIP5 multi-model decadal hindcasts over Australia from a hydrological viewpoint. Journal of Hydrology 519: 2932-2951.

Prefacing the findings of their study , Mehrotra et al. (2014) note that several century-scale simulations of hydrological variables for Australia that have been produced by General Circulation Models (GCMs) yield results that are "highly uncertain with a number of limitations which reduce their usefulness to guide local decision-making," citing the work of Suppiah et al. (2007), Perkins et al. (2007) and Maximo et al. (2008), while specifically noting in this regard: (1) the "coarser resolution of GCMs," (2) their "biases," (3) their "limited representation of sub-continental scale topography," as well as their limited representation of (4) "important offshore processes." So what did the five Australian researchers do to try to improve upon this sorry state of affairs?

As they describe it, they explored "the potential skill of Coupled Model Intercomparison Project (CMIP5) decadal hindcasts from 9 GCMs and their ensembles [78 for rainfall] over the period 1960-2010 from a hydrological perspective." And what did they thereby find? Quoting them again, they say that "the CMIP5 decadal simulations of rainfall exhibit very low skill when assessed across Australia and across a range of time-scales from yearly to longer which extend to the entire decade." And it is this finding that leads them to ultimately conclude that the current state of precipitation predictability "is not enough to drive impact models at decadal timescales and to influence policy and decision making."

Maximo, C.C., MvAvaney, B.J., Pitman, A.J. and Perkins, S.E. 2008. Ranking the AR4 climate models over the Murray-Darling Basin using simulated maximum temperature, minimum temperature and precipitation. International Journal of Climatology 28: 1097-1112.

Perkins, S.E., Pitman, A.J., Holbrook, N.J. and McAveney, J. 2007. Evaluation of the AR4 climate models' simulated daily maximum temperature, minimum temperature and precipitation over Australia using probability density functions. Journal of Climate 20: 4356-4376.

Suppiah, R., Hennessy, K.J., Whetton, P.H., McInnes, K., Macadam, I., Bathols, J., Ricketts, J. and Page, C.M. 2007. Australian climate change projections derived from simulations performed for the IPCC 4th Assessment Report. Australian Meteorological Magazine 56: 131-152.

Posted 11 May 2015