Rainfall and soil moisture drought projections and evaluation over Australia — Australian Meteorological and Oceanographic Society
  1. Schedule
  2. 25. The science of drought
  3. Rainfall and soil moisture drought projections and evaluation over Australia

Rainfall and soil moisture drought projections and evaluation over Australia (#266)

Vanessa Round 1 , Dewi Kirono 1 , Craig Heady 1 , Stacey Osbrough 1 , Francis Chiew 2
  1. CSIRO Oceans and Atmosphere, CSIRO, Aspendale, VIC, Australia
  2. CSIRO Land and Water, CSIRO, Canberra, ACT, Australia

Understanding future changes to the characteristics and occurrence of drought in Australia is of great importance, particularly for informing adaptation planning and decisions in the agriculture and water sectors. The latest national climate projections for Australia (CSIRO and BoM, 2015) included the Standardised Precipitation Index (SPI, an indicator of meteorological drought), from Global Climate Models (GCMs) which were evaluated on their performance at simulating climate variables and drivers but not specific drought metrics. We expand on current projections of drought for Australia over the 21st century by calculating the Standardised Soil Moisture Index (SSMI, an indicator of agricultural drought) as well as SPI, using CMIP5 GCMs. The models are evaluated on their representation of observed SPI-based drought metrics for the period 1900-2005. The projections and model evaluation explore five drought metrics (intensity, frequency, percent time in drought, mean duration and maximum duration) for multiple drought categories.

Model skill for simulating the spatial patterns of the SPI drought metrics is found to be poorer than for annual rainfall, with only a weak association between the two skill levels highlighting the value of evaluating models directly for the drought metric of interest. There is a large spread between model projections of SPI and SSMI for most drought metrics, with model selection not significantly influencing the projection uncertainty. We explore the significant projected increases in measures of drought for various regions of Australia and highlight the importance of considering soil moisture drought projections, which is generally more pronounced than rainfall drought. Projecting climate change impact on droughts, therefore, requires careful modelling consideration, interpretation and communication.

 

References:

CSIRO and Bureau of Meteorology 2015, Climate Change in Australia Information for Australia’s Natural Resource Management Regions: Technical Report, CSIRO and Bureau of Meteorology, Australia

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