Intermittent signature of ENSO in west-Antarctic precipitation

Abstract

Precipitation data from the new ERA40 reanalyses and from a 200-year simulation confirm a robust main mode of precipitation variability in west Antarctica. An intermittently strong ENSO signature is found in this mode. However, high correlation with ENSO indices appears infrequent. Thus, the high correlation found in ERA40, and previously in other chronologically realistic data, in the late 1980s and the 1990s may not be expected to last. Unlike previously suggested by others, the sign of the correlation between ENSO indices and west Antarctic precipitation, when significant, does not appear to change in time: Precipitation variability at the ENSO pace in the Bellingshausen-Weddell (Ross-Amunsden) region is consistently in phase (phase opposition, respectively) with the Southern Oscillation Index. This is consistent with a tropospheric wave train connecting the tropical Pacific and west Antarctic regions, which modulates in phase opposition the advection of air and moisture in the 2 regions. Copyright 2003 by the American Geophysical Union.