Centennial-Scale Variability in Atmospheric Circulation in Antarctica: Insights From a Coastal East Antarctic Ice Core Record

Abstract

A 108-m ice core (32SC) spanning the period from 1616 to 2016 CE was retrieved from coastal Princess Elizabeth Land (PEL), East Antarctica (69.97°S, 76.52°E, 1,113 m elevation). The ice core was analyzed to investigate the relationship between sea salt aerosols (SSAs), sea ice dynamics, and atmospheric circulation. The first component of Empirical Orthogonal Function analysis (32SC REOF1), which explains 58% of the variance in the ice core ions, serves as a proxy for SSAs. Time series correlation analysis reveals that sea ice had a minimal impact on 32SC REOF1. Instead, it showed a significant correlation with winter meridional atmospheric transport from the Southern Indian Ocean to PEL. The sea salt records exhibit a significant increase from the period 1616–1850 to 1851–2016 CE, with the mean value increasing by a factor of 2.4. This centennial-scale trend is likely linked to shifts in the position of the Southern Hemisphere Westerly Winds (SHWW). During the earlier period (1616–1850 CE), which was likely characterized by a colder climate, the SHWW in the Southern Indian Ocean sector may have shifted equatorward and weakened in intensity, potentially leading to reduced cyclone frequency and a subsequent decline in SSAs transport to high latitudes. In contrast, the period 1851–2016 CE, which is likely warmer, saw the SHWW shifted poleward, enhancing meridional wind speeds and increasing SSAs transport. Comparisons with other Antarctic ice core records suggest that the centennial-scale shift in the SHWW is a regional phenomenon, particularly pronounced in the Southern Indian Ocean.