Factors infuencing decadal variations in ENSO teleconnections

Abstract

The amplitude of midlatitude teleconnections linearly related to tropical Pacific sea surface temperatures has more than doubled in the quarter-century since 1976 relative to the prior quarter century. Over select portions of Pacific-North American region, an index of ENSO is shown to explain 25% of the interannual variability in the recent period compared to less than 10% of the variance during the period prior to 1976. An explanation is sought by examining the decadal variations in ENSO teleconnections occurring in ensemble atmospheric climate simulations of the 20th century, and the role of several plausible mechanisms is diagnosed.