Teleconnections of the tropical Atlantic and Pacific Oceans in a CMIP5 model ensemble

Abstract

This study investigates the teleconnections between the tropical Atlantic and Pacific Oceans in 15 state-of-the-art fully coupled general circulation models and Earth system models without external SST forcing. In contrast to other studies, the teleconnection is considered in both directions—from the Pacific to the Atlantic and from the Atlantic to the Pacific. The model ensemble is generally able to simulate the propagation of atmospheric and oceanic signals to the adjacent ocean basin, generated by warm sea surface temperature (SST) anomalies in the tropical eastern oceans with Atlantic summer events lagging or leading Pacific boreal winter events. This is investigated by means of time-lagged composite analyses of different atmospheric parameters, including sea level pressure, wind, stream function, velocity potential, vertical air movement and divergent wind at several levels. However, the modelled inter-basin teleconnection and its correct frequency of occurrence depend on the strong warm SST biases in the Atlantic Benguela upwelling region and in the Pacific Ocean.