Scientific article examining the downward trend in Australia's cyclone numbers : http://onlinelibrary.wiley.com/doi/10.1002/asl2.502/full http://onlinelibrary.w

Scientific article examining the downward trend in Australia's cyclone numbers : http://onlinelibrary.wiley.com/doi/10.1002/asl2.502/full http://onlinelibrary.wiley.com/doi/10.1002/asl2.502/full Long‐term changes in Australian tropical cyclone numbers "Numerous data quality checks were used in this study, as noted above, and there are no known systematic errors in the observations or analyses that would be likely to produce the decreasing trend in TC #s examined here. This suggests the possibility that the downward trend may be associated with changes in environmental conditions. Studies such as Emanuel (2005) indicate that the changes in various different environmental conditions that are occurring due to anthropogenic influences are having an influence on TC activity in some regions of the world. In the Australian region, one possible physical explanation for a decreasing trend in TC #s could be a potential long-term shift in environmental conditions towards a more El Niño-like state, given that fewer TCs tend to occur in the Australian region during El Niño than La Niña conditions. Although the NIN and SOI data used here did not show a significant long-term trend, some studies suggest the possibility of a shift towards more El Niño-like conditions, relating to a possible weakening of the Walker circulation due to increasing atmospheric greenhouse gas concentrations (Vecchi et al., 2006; Power and Smith, 2007; Huang et al., 2013; DiNezio et al., 2013). However, it is also noted that considerable uncertainty exists in observed changes to the Walker circulation based on reanalyses (Compo et al., 2011)."