Links between the subtropical Indian Ocean sea surface temperature and the tropical cyclones in Australia

The role of Indian Ocean sea surface temperature anomalies (SSTA) on the interannual variations of Australian tropical cyclone (TC) activity remains largely unexplored. A recent observational study has shown that fluctuations in year-to-year TC counts are significantly correlated with SSTA variability in the subtropical Indian Ocean for the period 1969-2013. Generally, an active (inactive) TC season in the Australian region is associated with an anomalous cooling (warming) of the subtropical Indian Ocean. This SSTA pattern is also accompanied by an El Niño – Southern Oscillation signature. In this study, we explore the links between the Indian and Pacific SSTA patterns and the Australian TC season using observations and a suite of high-resolution experiments. More specifically, the atmospheric component of the NCAR Community System Earth Model (CESM) is forced with a composite of SSTA pattern during active and inactive Australian TC seasons. Idealized experiments are also used to understand the relative contributions of the Indian and Pacific Oceans to Australian TCs. Despite underestimating the intensity of severe TC events, the simulations suggest that the Indian Ocean SSTA plays an important role in modulating the number of TC events for Australia. Results are currently being investigated to understand the physical mechanisms at play.