El Nino Since the Early-1990s Climate Shift in the Pacific

Abstract:

A comprehensive set of analyses based on observations and models are presented to show that significant changes occurred in broad areas of the low-latitude Pacific in the early 1990s. Associated with this early-1990s climate shift, the strength of ocean-atmosphere coupling in the eastern subtropical Pacific intensified, which resulted in a shift in the location of El Nino events from the eastern Pacific (EP) to the central Pacific (CP). The CP type of El Nino events are accompanied by stronger subtropical precursors than the EP type of El Nino.

Our investigations indicate that this early-1990s climate shift is characterized by an intensification of the subtropical Pacific High and is linked to a phase change of the Atlantic Multi-decadal Oscillation (AMO) that occurred at about the same time. The talk will describe the sequence of physical processes that enable the AMO to impact the low-latitude Pacific climate and its variability.