Definition of Antarctic Oscillation index
Article first published online: 7 DEC 2012
Copyright 1999 by the American Geophysical Union.
Geophysical Research Letters
Volume 26, Issue 4, pages 459–462, 15 February 1999
How to Cite
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 14 DEC 1998
- Manuscript Received: 9 JUL 1998
Following Walker's work about his famous three oscillations published during the 1920–30s, many papers were written about atmospheric oscillations. A fourth atmospheric oscillation in the middle and high southern latitudes was found, and named the Antarctic Oscillation (AO). AO refers to a large scale alternation of atmospheric mass between the mid-latitudes and high latitudes surface pressure. In order to understand the spatial structure of sea level pressure variation in detail, empirical orthogonal function analysis is applied. An objective index of the Antarctic Oscillation Index (AOI) is defined as the difference of zonal mean sea level pressure between 40°S and 65°S. The AOI has the potential for clarifying climate regimes in the southern hemisphere, similar to how the NAO and the NPO has been used in the northern hemisphere.