The impact of the 1997--1998 ENSO event is presented in context of axial Earth-atmosphere angular momentum exchange utilizing length of day (LOD), Southern Oscillation Index (SOI) and atmospheric angular momentum (AAM) data from 1970 to 1998; comparisons are made with previous events. The analysis of equal-area latitudinally belted AAM from the NCEP reanalysis (1958-98) reveals slow global coherent poleward propagation of angular momentum. These structures originate in the equatorial regions, penetrate into high latitudes and are bimodal in nature with variations centered at low-frequency (LF~4.7 yr) and quasi-biennial (QB~2.4 yr) periods. Analyses utilize both a recursive filter and multichannel singular spectrum analysis (M-SSA). ¿ 1999 American Geophysical Union