1996 Articles

Cycling around the South Pole

Yuan, Xiaojun; Cane, Mark A.; Martinson, Douglas G.

Many of the variations in climate we all observe (and enjoy, or suffer) seem to be randomly distributed in time and space. While this view has an irreducible element of truth, there is increasing evidence that much of the Earth's climate variability arises from a structured, global, interconnected system. On page 699 of this issue 1, White and Peterson provide a striking example, with evidence for an interannual 'Antarctic Circumpolar Wave' (ACW). This is not a water wave but a disturbance in sea-ice extent, in sea surface temperature, in surface wind speed, and in atmospheric pressure at sea level. Although the short history of measurements in the Antarctic region rules out a definitive description, the data available from the past 15 years show a two-wavelength ACW propagating around Antarctica (see Fig. 1) with a frequency of about 4-5 years. This wave in the ocean, atmosphere and cryosphere (ice) is a strong and significant part of the interannual variability in the southern polar region.