Water mass subduction and the transport of phytoplankton in a coastal upwelling system

Libe Washburn, David C. Kadko, Burton H. Jones, Thomas Hayward, P. Michael Kosro, Timothy P. Stanton, Steve Ramp, Timothy Cowles

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


Observations during the Coastal Transition Zone (CTZ) experiment in summer 1988 reveal the presence of deep phytoplankton layers in a coastal upwelling system. The layers occur throughout the CTZ study area, including a strong baroclinic jet which was present over the period of the experiment. On the basis of a variety of bio-optical, hydrographic, and geochemical indicators, it is concluded that the water masses associated with the layers result from subduction processes. Criteria are developed for identification of subducted water masses based on the beam attenuation coefficient, chlorophyll fluorescence, and distribution of light in the water column. Temperature-salinity characteristics are consistent with two source regions for the subducted layers, one nearshore and a second farther offshore. Most of the layers correspond to the inshore source which is apparently distributed alongshore. Subducted water masses are found in all six grid surveys of the CTZ experiment and probably result from a variety of physical processes. One of these is flow along sloping isopycnal surfaces due to advection and mixing processes. Advection time scales for flow out the axis of the jet range from a few days to a few weeks, depending on the depth of a particular surface, and the bio-optical indicators for subduction processes persist over these time scales.

Original languageEnglish (US)
Pages (from-to)14927-14945
Number of pages19
JournalJournal of Geophysical Research: Oceans
Issue numberC8
StatePublished - Aug 15 1991
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright 1991 by the American Geophysical Union.

ASJC Scopus subject areas

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


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