Interdecadal sea level fluctuations at Hawaii

• Main Authors: Yvonne L. Firing, Mark A. Merrifield, Thomas A. Schroeder, Bo Qiu
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Curl; Pacific; aleutian low
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.611.8298; http://www.soest.hawaii.edu/jimar/review/posters/draft01_mar_04pp.pdf

Over the past century, tide gauges in Hawai‘i have recorded interdecadal sea level variations that are coherent along the island chain. The generation of this signal and its relationship to other interdecadal variability are investigated, with a focus on the last decade. Hawai‘i sea level is correlated with sea surface height (SSH) over a significant portion of the North Pacific, and with the Pacific North America (PNA) index, which represents teleconnections between tropical and mid-latitude atmospheric variations. Similar variations extend well below the thermocline in World Ocean Atlas (WOA) temperature. Comparison with NCEP reanalysis wind and pressure shows that high (low) sea level phases around Hawai‘i are associated with an increase (decrease) in the strength of the Aleutian Low. The associated wind stress curl pattern is dynamically consistent with observed sea level anomalies, suggesting that sea level at Hawai‘i represents large-scale changes that are directly wind-forced in concert with the PNA. Atmospheric modulation, as opposed to Rossby wave propagation, may explain the linkage of Hawai‘i sea level to North American sea level and ENSO events. A wind-forced, baroclinic Rossby wave model replicates some aspects of the interdecadal SSH variations and their spatial structure, but fails to predict them in detail near Hawai‘i. The accuracy of wind products in this region and over this time period may be a limiting factor. Variations in mixed-layer temperature due to surface heat flux anomalies may also contribute to the interdecadal sea level signal at Hawai‘i. 1