Global influence of the Northern hemisphere second mode of the zonal average of the zonal wind

The authors examine the impact of two zonal wind modes in the northern hemisphere (Northern Annular Mode, NAM, and the second zonal wind mode) on the global domain during the normal (non-El Niño/Southern Oscillation, ENSO) northern winter from 1981-2002. It is found that both modes are in association with tropical zonal wind anomalies, but only the second zonal wind mode has significant linkage with the Southern Annular Mode (SAM), particularly leading about 6-19 days. This kind of linkage can also be found in extended datasets but only evident since 1974. Copyright 2006 by the American. Geophysical Union.