Three-dimensional oceanic eddy analysis in the Southern California Bight from a numerical product

摘要

With eight islands, complex coastlines and bottom topography, strong wind curls, and frequent upwelling fronts, the Southern California Bight (SCB) is an area with strong eddy activity. By applying an automated eddy detection scheme to a 12 year high-resolution numerical product of the oceanic circulation in the SCB, a three-dimensional eddy data set is developed. It includes information for each eddy’s location, polarity, intensity, size, boundary, and moving path at nine vertical levels. Through a series of statistical analyses applied to the eddy data set, three-dimensional statistical characteristics of mesoscale and submeoscale eddy variations in the SCB are elucidated; these shed light on how eddies are generated, evolve, and terminate. A significant percentage of eddies is found to be generated around islands and headlands along the coastline, which indicates that islands in the SCB play a vital role in eddy generation. Three types of eddies, based on shape, are identified from the numerical product: bowl, lens, and cone. A dynamic analysis shows that some submesoscale eddies with finite local Rossby numbers tend to be ageostrophic balanced while mesoscale eddies are in geostrophic balance. The present research results are useful for the interpretation of data sets obtained during the interdisciplinary Santa Barbara Channel Radiance in a Dynamic Ocean (RaDyo) field experiment conducted on September 3–25, 2008.