Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 14, 597-615, 2017
https://doi.org/10.5194/bg-14-597-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
07 Feb 2017
Describing rainfall in northern Australia using multiple climate indices
Cassandra Denise Wilks Rogers1 and Jason Beringer1,2 1School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800, Australia
2School of Earth and Environment (SEE), University of Western Australia, Crawley, WA, 6009, Australia
Abstract. Savanna landscapes are globally extensive and highly sensitive to climate change, yet the physical processes and climate phenomena which affect them remain poorly understood and therefore poorly represented in climate models. Both human populations and natural ecosystems are highly susceptible to precipitation variation in these regions due to the effects on water and food availability and atmosphere–biosphere energy fluxes. Here we quantify the relationship between climate phenomena and historical rainfall variability in Australian savannas and, in particular, how these relationships changed across a strong rainfall gradient, namely the North Australian Tropical Transect (NATT). Climate phenomena were described by 16 relevant climate indices and correlated against precipitation from 1900 to 2010 to determine the relative importance of each climate index on seasonal, annual and decadal timescales. Precipitation trends, climate index trends and wet season characteristics have also been investigated using linear statistical methods. In general, climate index–rainfall correlations were stronger in the north of the NATT where annual rainfall variability was lower and a high proportion of rainfall fell during the wet season. This is consistent with a decreased influence of the Indian–Australian monsoon from the north to the south. Seasonal variation was most strongly correlated with the Australian Monsoon Index, whereas yearly variability was related to a greater number of climate indices, predominately the Tasman Sea and Indonesian sea surface temperature indices (both of which experienced a linear increase over the duration of the study) and the El Niño–Southern Oscillation indices. These findings highlight the importance of understanding the climatic processes driving variability and, subsequently, the importance of understanding the relationships between rainfall and climatic phenomena in the Northern Territory in order to project future rainfall patterns in the region.

Citation: Rogers, C. D. W. and Beringer, J.: Describing rainfall in northern Australia using multiple climate indices, Biogeosciences, 14, 597-615, https://doi.org/10.5194/bg-14-597-2017, 2017.
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Short summary
Savannas are extensive yet sensitive to variability in precipitation. We examined the relationship between climate phenomena and historical rainfall variability across Australian savannas using 16 climate indicies. Seasonal variation was most correlated with the Australian Monsoon Index, whereas interannual variability was related to a greater number of phenomena. Rainfall variability and the underlying climate processes driving variability are important.
Savannas are extensive yet sensitive to variability in precipitation. We examined the...
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