Abstract

The El Niño-Southern Oscillation (ENSO) drives stationary Rossby waves that play an important role in Southern Hemisphere weather and climate, including promoting Australian rainfall variability. However, the development of these teleconnection patterns, typically shown on a seasonal timescale, and their interactions with synoptic weather systems are not fully understood. In this seminar, I will explore the mechanisms involved in the establishment of ENSO teleconnections in the Southern Hemisphere and their impacts on weather systems. In the first part, I will examine the mechanisms behind the asymmetric extratropical height response to westward-located and eastward-located ENSO heating using a set of large-ensemble experiments with prescribed equatorial diabatic heating anomalies. The relative importance of non-linear effects will be assessed by contrasting the comprehensive experiments with results from a simple linear model. In the second part, I will link changes in the large-scale atmospheric circulation during ENSO events to rain-producing synoptic weather systems in eastern Australia, thereby refining our understanding of how ENSO actually influences the weather.