EGU22-432, updated on 26 Mar 2022
https://doi.org/10.5194/egusphere-egu22-432
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

The decadal modulation of the ENSO-Australian monsoon rainfall teleconnection 

Hanna Heidemann1,2, Joachim Ribbe2, Tim Cowan1,3, and Benjamin J. Henley4,5,6
Hanna Heidemann et al.
  • 1Centre for Applied Climate Sciences, University of Southern Queensland, Toowoomba, Australia
  • 2School of Sciences, University of Southern Queensland, Toowoomba, Australia
  • 3Bureau of Meteorology, Melbourne, Australia
  • 4School of Earth, Atmosphere and Environment, Monash University, Australia
  • 5Department of Infrastructure Engineering, University of Melbourne, Parkville, Australia
  • 6ARC Centre of Excellence for Climate Extremes, Monash University, Australia

We analyse the decadal variability in the relationship between Australian monsoon rainfall (AUMR) and the El Niño Southern Oscillation (ENSO). A composite analysis is conducted to examine monsoon season (December to March) rainfall anomalies over northern Australia during central and eastern Pacific ENSO events between 1920 to 2020. These composites are evaluated separately for positive and negative phases of the Interdecadal Pacific Oscillation (IPO) and reveal differences in AUMR anomalies with respect to ENSO event diversity. During central Pacific (CP) El Niño events, the key month is February, in which the AUMR is above average in positive IPO phases and below average during negative IPO phases. This is due to low-level circulation anomalies northwest of Australia, which are cyclonic in the positive IPO phases and anticyclonic in negative IPO phases, in addition to moisture fluxes directed towards the central Pacific, away from northern Australia. During CP La Niña events, there are insignificant rainfall anomalies over northern Australia in December during positive IPO phases. In contrast, during negative IPO phases, strong and significant positive rainfall anomalies cover much of northern and eastern Australia, which relate to large-scale convergence of moisture and an intensification of the Walker Circulation. In summary, AUMR anomalies during CP ENSO events differ between positive and negative phases of the IPO due to variability in the large-scale atmospheric circulation.

How to cite: Heidemann, H., Ribbe, J., Cowan, T., and Henley, B. J.: The decadal modulation of the ENSO-Australian monsoon rainfall teleconnection , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-432, https://doi.org/10.5194/egusphere-egu22-432, 2022.