Asymmetry of the Antarctic Oscillation in Austral Autumn

• Published in: Geophysical Research Letters
• Main Authors: Yuheng Tang, Anmin Duan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2023
• Subjects: Antarctic oscillation; zonal asymmetry; self‐organizing map; Geophysics. Cosmic physics; QC801-809; Antarctic; Antarctic Peninsula; Austral; Pacific; The Antarctic; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.1029/2023GL105678; https://doaj.org/article/b587c0979d8f415891fe0318a729c1db

Abstract The annular structure of Antarctic oscillation (AAO) is a research hotpot, but its asymmetry receives less attention. In this paper, the self‐organizing map method is employed to cluster the AAO patterns into symmetric and asymmetric modes in austral autumn. The asymmetry is mainly reflected in the Pacific‐Atlantic sector, and the AAO evolves toward asymmetric positive polarity, with the most pronounced asymmetry in May. Originating from near Australia, the asymmetry indicates a zonal wave train in the Pacific‐Atlantic sector. Both modeled and observed results demonstrate that the sea surface temperature anomaly in the equatorial western Pacific stimulates a local meridional circulation anomaly and induces anomalous Rossby wave sources near Australia subsequently. An anomalous wave train propagating toward the Antarctic Peninsula is formed, and the associated geopotential anomaly enhances the asymmetry of AAO. Asymmetric AAO is conducive to the Antarctic dipole, which modulates the air temperature and sea ice anomalies around Antarctica.