The changing impact of El Niño on US winter temperatures

Abstract

In this study, evidence is presented from statistical analyses, numerical model experiments, and case studies to show that the impact on US winter temperatures is different for the different types of El Niño. While the conventional Eastern‐Pacific El Niño affects winter temperatures primarily over the Great Lakes, Northeast, and Southwest US, the largest impact from Central‐Pacific El Niño is on temperatures in the northwestern and southeastern US. The recent shift to a greater frequency of occurrence of the Central‐Pacific type has made the Northwest and Southeast regions of the US most influenced by El Niño. It is shown that the different impacts result from differing wave train responses in the atmosphere to the sea surface temperature anomalies associated with the two types of El Niño.