CMCC Seminar
16 July at 11:00 CEST – The seminar will take place at CMCC-Bo meeting room, Viale B.Pichat 6/2 2nd floor and via Zoom (access code 574659)

Speaker:
Elio Campitelli, Monash University, Research Fellow

Abstract:
Despite the Southern Hemisphere’s large-scale circulation being much more zonally symmetric than that of the Northern Hemisphere, zonally anomalous circulation anomalies have significant regional impacts. They affect weather systems and regional climates though the meridional transport of heat, moisture, and momentum, and they are implicated in the occurrence of high-impact weather extremes. Even the primary mode of extratropical variability, the Southern Annular Mode (SAM), shows significant deviations from zonal symmetry, its name notwithstanding. This part of the circulation has been primarily studied using Empirical Orthogonal Functions, which highlight the PSA1 and PSA2 modes, and Fourier analysis, which identifies zonal waves 1 and 3 as key features. However, these methods have limitations and fail to capture important aspects of atmospheric circulation. In this talk, I will demonstrate that using complex Empirical Orthogonal Functions combines the advantages of both methods. Additionally, by separating the SAM into its zonally symmetric and zonally asymmetric components, we can gain further insights into variability, forcing, and impacts, and suggests a unified view of asymmetric and symmetric circulation variability in the Southern Hemisphere.