The Antarctic Circumpolar Wave and Indo-Pacific Climate
Peter G. Baines
CSIRO Atmospheric Research Aspendale 3195 Australia
There is as yet no clear consensus as to the principal mechanism that causes the Antarctic Circumpolar Wave. Mechanisms that have been suggested so far include (i) air-sea exchanges of heat and momentum between atmosphere and the Southern Ocean, causing growth through positive feedback, and (ii) oceanic teleconnections from the South Pacific. A third mechanism, which is advanced here, is that the ACW is primarily initiated by atmospheric teleconnections in the South Pacific, in the form of the Pacific-South American pattern (PSA), and evidence for this is presented. The PSA pattern may be energised by tropical convection, but may also arise from instability of the basic flow, and from random higher frequency forcing associated with the main southern mid-latitude storm track.
The associated warm and cold anomalies in the Southern Ocean are advected into the Indian and Pacific Oceans, where they may impact on weather and climate through effects on atmospheric humidity and rainfall.
