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Eddy Quest – On the Trail to Derive Useful Information about Small-scale Eddies from SAR Observations
Benjamin Holt(1) (1) Jet Propulsion Laboratory, NASA, Washington, United States
Abstract
The coastal region off Southern California has been found to be replete with small-scale eddies. Their small-size (often less than 10 km in diameter), rapid evolution, and short-term life cycle has rendered these eddies elusive and challenging to observe and measure. Fine-resolution synthetic aperture radar (SAR) imagery has proven to be an effective observational tool to detect such eddies, primarily based on surfactant patterns traced out by the underlying eddy flow field. This paper will describe eddy observations derived from spaceborne SAR, comparisons with models and other remotely sensed data, and finally results of an aircraft SAR and boat campaign designed to detect and direct a boat to eddies located near Catalina Island to obtain in situ measurements of their physical properties. Surface flow maps were derived from the rapid-repeating airborne SAR imagery and a set of ADCP and CTD transects were made near the eddies, but unfortunately not successfully through the eddy core region. The most likely formation mechanism for these spiral eddies is current-wake instability related to the flow of the Southern California Countercurrent along the north shore of Catalina. A new plan of attack to capture in situ eddy measurements will be described.
Workshop presentation
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