Wave-driven sea level anomalies at the Midway tide gauge as an index of North Pacific storminess over the past 60 years

Jérôme Aucan (1) , R. Hoeke (2) , M.A. Merrifield (3)

1 OLVAC - Océan du Large et Variabilité Climatique
2 CSIRO - CSIRO Marine and Atmospheric Research
3 Department of Oceanography

Sixty years of sea-level data collected in the interior lagoon of Midway Atoll in the northern Hawaiian Islands are used to examine short-term (<2 days), high amplitude (up to 1 m) sea level anomaly (SLA) events that occur during the winter months. A combination of wind and wave model hindcasts, satellite altimetry product and in-situ water level data confirms that these high SLA events are driven primarily by the arrival of energetic swell waves generated by storms in the North Pacific as breaking waves on the northwest side of the atoll lead to the setup of the lagoon. The number of high SLA events recorded in Midway during each winter season correlates well with the storminess in the Central North Pacific, defined as the mean seasonal wave height. This leads us to conclude that the seasonal number of high SLA events measured at this specific tide gauge in Midway can be used as an index of storminess in the Central North Pacific over climatic time-scales. Our Midway-based index of storminess correlates well with the Pacific Decadal Oscillation (PDO) index, and its observed increase over the past 60 years is attributed to variability associated with the PDO rather than a long-term trend.

Domaines: Océan, Atmosphère

Jérôme Aucan, R. Hoeke, M.A. Merrifield. Wave-driven sea level anomalies at the Midway tide gauge as an index of North Pacific storminess over the past 60 years. Geophysical Research Letters, 2012, 39 (17), pp.L17603. ⟨10.1029/2012GL052993⟩. ⟨hal-00798722⟩