The March 1997 Westerly Wind Event and the Onset of the 1997/98 El Niño: Understanding the Role of the Atmospheric Response

In a previous study, the effect of the March 1997 Westerly Wind Event (WWE) on the evolution of the tropical Pacific Ocean was studied using an ocean general circulation model (GCM). The response was characterized by (i) a cooling of the far western Pacific (0.8C), (ii) a rapid eastward displacement of the warm pool (2000 km in a month), and (iii) a weak warming of the central eastern Pacific along the path of the oceanic Kelvin wave, excited by the WWE (0.5C). In this study, the atmospheric response to these aspects of the sea surface temperature (SST) response are investigated using an atmospheric GCM forced with the SST anomalies from the ocean-only experiments.