Northwest Swell Variability at the Hawaiian Islands

Abstract

The influence of Pacific climate variability on the wind wave field at Hawai‘i is examined by identifying the regional winds that are most influential in driving waves in the winter. We demonstrate how the ESTELA (a method for Evaluating the Source and Travel-time of the wave Energy reaching a Local Area) model can be used to identify source regions using wave buoys around the islands for initialization and validation. We examine changes in the source wind field that drive the dominant northwest swell energy that arrives during winter months, and compare these variations with the prominent climate modes and storm tracks of the north Pacific. A case study of the impact of variations in the energy flux is conducted at Baldwin Beach on the north shore of Maui Island. We find that northwest winter swells are closely related to the North Pacific Index, sea level pressure at 42.5 N, 150 W, an increase in the number of extratropical storms, more southerly storm tracks, and an intensified east asian jet stream.