On the changing relationship between North Pacific climate variability and synoptic activity over the Hawaiian Islands

Abstract

The teleconnection between tropical and extratropical climates in the North Pacific and continental regions of eastern Asia and western North America is known to vary on decadal to multidecadal time scales. In this study, the teleconnection pattern is studied with observational and reanalysis data products. The regional focus is set on the Hawaiian Islands in the central subtropical part of the North Pacific. By analysing correlations between regional climate indices and large-scale climate modes during the years 1980 and 2014, it was found that the correlation between El Niño—Southern Oscillation (ENSO) and the synoptic weather activity over the Hawaiian Islands decreased over time. Composite analysis of the geopotential height anomalies and upper level winds suggest that the systematic shift in the North Pacific Jet (NPJ) position had an impact on the teleconnection between tropical Pacific SST and winter storm activity and precipitation variability in Hawai'i. The change in the correlations and in the NPJ structure coincides with a transition from the positive phase of the Pacific Decadal Oscillation (PDO) towards a neutral and weak negative state. This observation-based study provides a central subtropical Pacific viewpoint in support of the growing body of research studies that have reported a major shift in the Pacific climate system during the mid-1990s. The article further discusses the potential role of decadal-scale changes in the North Pacific Oscillation (NPO) phase in changing the strength of the ENSO teleconnection with synoptic activity over the Hawaiian Islands. The results of this study are relevant to paleoclimate interpretation of individual proxy records as well as for regional downscaling of future rainfall for the Hawaiian Islands.