An oceanic cyclonic eddy on the lee side of Lanai Island, Hawaii

Abstract

A young cold core cyclonic eddy displaying a significant increase in surface chlorophyll was observed offshore Lanai Island, Hawaii, where the Marine Optical Buoy (MOBY) is located. During one of its deployments, MOBY broke free from its mooring. In the course of its 3-day free drifting period, MOBY followed a cyclonic eddy, which is manifested by satellite remote sensing data, chlorophyll data from Moderate Resolution Imaging Spectroradiometer, and sea surface temperature (SST) from a Geostationary Operational Environmental Satellite. The time series of the SST show that the cold core eddy was in a formative stage. It existed as a stand-alone eddy for about 9 days before it merged with cold water south of Oahu Island. A high-resolution numerical model simulation reproduces similar eddies in terms of location, size, and intensity. An eddy detection algorithm is described and applied to locate and track the modeled eddies. The results demonstrate that mesoscale and submesoscale eddies are frequently generated on and pass through the lee side of Lanai Island and the statistical analysis quantifies the general features of eddies in the area. Copyright 2009 by the American Geophysical Union.