Drought-sensitive tree-ring chronologies from Arnhem Land, monsoonal Australia — Australian Meteorological and Oceanographic Society

Drought-sensitive tree-ring chronologies from Arnhem Land, monsoonal Australia (#197)

Kathryn Allen 1 , Matthew Brookhouse 2 , Jonathan Palmer 3 , Brittany Dahl 4 , Declan Norrie 5 , Ben French 6 , Lynda Prior 6 , David Bowman 6 , Patrick Baker 1
  1. Ecosystem and Forest Sciences, University of Melbourne, Richmond, Victoria, Australia
  2. Fenner School of Environment and Society, Australian National University, Canberra, ACT, Australia
  3. ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
  4. CIT Consulting, Canberra, ACT, Au
  5. Proximity, Canberra, ACT, Australia
  6. School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia

The biodiversity and ecological dynamics of the Australian monsoon tropics is fundamentally shaped by dry conditions over the months of May to October followed by the highly variable wet season rainfall of November to April. Such variability combined with short instrumental records makes highly resolved terrestrial palaeoclimate records from northern Australia prior to 1900 CE of considerable scientific interest. Here, we present two well-replicated Callitris intratropica ring-width chronologies from Arnhem Land in northern Australia, one of which extends the tree-ring record in the region by another 86 years, back to 1761. Both chronologies have clearly defined regional patterns of correlations with temperature, precipitation, potential evapotranspiration and the Standardised Precipitation Evapotranspiration Index (SPEI) across the lower latitudes of the Northern Territory. We demonstrate their strong potential for reconstructing drought over the latter part of the wet season and show that narrow rings are most strongly linked with dry conditions in northwestern Australia. This is most likely associated with the weaker penetration of monsoonal rainfall occurring at the end of the wet season. In contrast, the occurrence of wider rings coincides with wetter conditions to the southeast, south of the Gulf of Carpentaria and into Queensland.  To develop a spatially extensive reconstruction that could potentially provide information linked to ENSO dynamics over earlier centuries, additional site chronologies of C. intratropica in the region will be required. Hydroclimate reconstructions for this region have the potential to provide important baseline information for understanding the rate and magnitude of current and projected regional climate change.

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