An Antarctic Circumpolar Wave (ACW) is simulated by a global coupled ocean-atmosphere model. Time-longitude diagrams of anomalies in sea-surface temperature (SST) and sea-surface salinity (SSS) show that anomalies propágale eastward, taking 20-30 years to encircle the pole. The time taken is 2-3 times longer than indicated by observations, due to the relatively slow speed of the modelled Antarctic Circumpolar Current (ACC). High-SSS anomalies correspond to high-SST anomalies and high-density anomalies, and thus to low sea-surface height anomalies, indicating that salinity IS a dominant factor for dynamics with in the Southern Ocean and is indispensable for understanding the mechanism of the ACW. Sea-ice formation is suppressed southward of warm, saline surface-water regions. High sea-ice concentration anomalies correspond to thick sea-ice anomalies. Empirical orthogonal function analyses of SSTanomalies for both model and observation show that the dominant mode in the Southern Ocean has a spatial pattern closely related to El Niño activity. Sea-level pressure (SLP) anomalies propagate eastward with the ACW. High SLP anomalies in the atmosphere correspond to low-density anomalies 111 the ocean. The ACC has clockwise geostrophic velocity anomalies over high-density anomaly regions with upwelling. Both heat and salt are transported from the deep layer to the surface layer by upwelling. This could suppress sea-ice formation directly. Anomalous horizontal advection of heat and salt by geostrophic velocity anomalies in the ACC appears to influence the anomalies in SST, SSS and sea ice.