A view of the 1993-1994 California Current based on surface drifters, floats, and remotely sensed data

K. H. Brink, R. C. Beardsley, J. Paduan, R. Limeburner, M. Caruso, J. G. Sires

Research output: Contribution to journalReview articlepeer-review

49 Scopus citations

Abstract

Near-surface drifters were deployed in the California Current System during the period 1993-1994 in order to study mean and eddy currents. The deployment scheme allowed a 2 year period where data density was high enough to make meaningful estimates of eddy statistics and of seasonal mean currents and variances on a 5° grid. Eddy variability, which tended to be isotropic, was higher near the coast (standard deviations around 0.2 m s-1) and decreased offshore (down to ∼0.1 m s-1). Seasonal mean surface flow west of California was southward during all seasons: if a Davidson Current existed during 1993-1995, it was probably either short-lived or only found closer to the coast than our study area, i.e., within 100-150 km of shore. In some cases, drifter populations within a discrete feature were high enough to allow some detailed resolution of its behavior. We note a tendency for individual eddies (which can last for up to 3-5 months) to drift westward at rates of O(5 km day-1). Not all eddies in the region are surface-intensified. There is clear evidence for at least the occasional presence of a thin, meandering southward jet in the region that can be 1000 km or more long. This jet can be identified with that found in the Coastal Transition Zone program in association with cool filaments. The jet appears to become broader and slower south of Point Conception. We hypothesize (on the basis of others' results as well as ours) that the eddies that are strongest at the surface result primarily from instabilities on a southward alongshore mean current and that eddies that are maximal at depth are spawned by the northward undercurrent.

Original languageEnglish (US)
Article number1999JC900327
Pages (from-to)8575-8604
Number of pages30
JournalJournal of Geophysical Research: Oceans
Volume105
Issue numberC4
DOIs
StatePublished - Apr 15 2000
Externally publishedYes

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

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