Coupling of Biennial Oceanic Rossby Waves with the Overlying Atmosphere in the Pacific Basin

Abstract

Abstract Anomalies of TOPEX/Poseidon sea level height (SLH), NCEP sea surface temperature (SST), and ECMWF meridional surface wind (MSW) and derived wind stress curl (WSC) are mapped biweekly over the global ocean from 60°S to 60°N for two years from 1993 to 1994. These anomalies (i.e., differences from the average over the two years) allow one cycle of biennial climate change to be examined, with the paucity of temporal degrees of freedom mitigated by greater numbers of spatial degrees of freedom. Time–longitude diagrams of SLH anomalies reveal biennial Rossby waves in the Pacific ocean with westward phase speeds in the extratropics (Tropics) faster (slower) than expected of free biennial Rossby waves. Complex empirical orthogonal function analysis of SLH, SST, MSW, and WSC anomalies finds the beta-refraction pattern of these biennial Rossby waves in all four variables over most of the eastern-central Pacific Ocean, suggesting that oceanic Rossby waves there are coupled with the overlying atmosphere. The...