The Origin and Propagation of the Antarctic Centennial Oscillation

• Published in: Climate
• Main Authors: W. Jackson Davis, Peter J. Taylor, W. Barton Davis
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2019
• Subjects: Antarctic Circumpolar Current; Antarctic Circumpolar Vortex; Antarctic drill sites; Antarctic Oscillation; anthropogenic global warming; climate policy; Holocene; ice cores; Last Glacial Maximum; Last Glacial Termination; natural climate cycle; natural global warming; relaxation oscillation; Southern Annular Mode; stable isotope temperature proxies; teleconnection; Science; Q; Antarctic; Southern Ocean; The Antarctic; Antarc*; Antarctica
• Online Access: https://doi.org/10.3390/cli7090112; https://doaj.org/article/6956cd1156d649478e696e548d52413d

The Antarctic Centennial Oscillation (ACO) is a paleoclimate temperature cycle that originates in the Southern Hemisphere, is the presumptive evolutionary precursor of the contemporary Antarctic Oscillation (AAO), and teleconnects to the Northern Hemisphere to influence global temperature. In this study we investigate the internal climate dynamics of the ACO over the last 21 millennia using stable water isotopes frozen in ice cores from 11 Antarctic drill sites as temperature proxies. Spectral and time series analyses reveal that ACOs occurred at all 11 sites over all time periods evaluated, suggesting that the ACO encompasses all of Antarctica. From the Last Glacial Maximum through the Last Glacial Termination (LGT), ACO cycles propagated on a multicentennial time scale from the East Antarctic coastline clockwise around Antarctica in the streamline of the Antarctic Circumpolar Current (ACC). The velocity of teleconnection (VT) is correlated with the geophysical characteristics of drill sites, including distance from the ocean and temperature. During the LGT, the VT to coastal sites doubled while the VT to inland sites decreased fourfold, correlated with increasing solar insolation at 65°N. These results implicate two interdependent mechanisms of teleconnection, oceanic and atmospheric, and suggest possible physical mechanisms for each. During the warmer Holocene, ACOs arrived synchronously at all drill sites examined, suggesting that the VT increased with temperature. Backward extrapolation of ACO propagation direction and velocity places its estimated geographic origin in the Southern Ocean east of Antarctica, in the region of the strongest sustained surface wind stress over any body of ocean water on Earth. ACO period is correlated with all major cycle parameters except cycle symmetry, consistent with a forced, undamped oscillation in which the driving energy affects all major cycle metrics. Cycle period and symmetry are not discernibly different for the ACO and AAO over the same time periods, suggesting that ...