Seminar by Dr. Linyuan Sun from Postdoc Research Fellow, Climate Change Research Center, UNSW, Sydney
28 July 2025
KST 15:00
The Seminar is being held in Room 1010 (Jasmin) – Integrated mechanical engineering building. Click here for the campus map.
The influence of El Niño-Southern Oscillation (ENSO) on Australian rainfall varies with its Eastern Pacific (EP) and Central Pacific (CP) types. Here we revisit the EP/CP ENSO’s impact on Australian spring rainfall using updated in-situ observations and ERA5 reanalysis from 1950 to 2024. EP ENSO induces regionally dispersed rainfall anomalies, concentrated in the Northern Territory, Murray-Darling Basin, and southwest Western Australia—an area traditionally considered less affected by ENSO. In contrast, CP ENSO induces a broader, continental-scale rainfall response across northern to eastern Australia. These contrasting rainfall patterns stem from differences in moisture transport and surface evaporation modulated by anomalous atmospheric circulation. EP El Niño co-occurs with a positive Indian Ocean Dipole (IOD), producing a Rossby wavetrain from tropical Indian Ocean that anchors an equivalent-barotropic anticyclone south of Australia. Accompanying weak co-variability with IOD, CP El Niño features westward-shifted enhanced equatorial Pacific convection, causing a zonally elongated Pacific-South America pattern with an equivalent-barotropic cyclone near Australia’s east coast. Shifts in equatorial Pacific convection anomaly are crucial for rainfall increase responding to La Niña events (mainly CP type), through a stronger equivalent-barotropic Tasman Sea high-pressure anomaly. In addition to the differences of tropical processes, we highlight the critical role of extratropical transient eddy feedback in maintaining midlatitude equivalent-barotropic circulation anomalies that affect Australian climate.