Diel variations of bio-optical properties in the Sargasso Sea

Michael Hamilton, T. C. Granata, T. D. Dickey, J. D. Wiggert, D. A. Siegel, J. Marra, C. Langdon

Research output: Contribution to journalConference articlepeer-review

15 Scopus citations


Concurrent time series measurements including: percent transmission of a collimated beam of 660 nm light (converted to beam attenuation coefficient, C), photosynthetically available radiation (PAR), and chlorophyll (chl) fluorescence were obtained at 7-8 depths within the upper 160m of the Sargasso Sea (34N 70W) from Mar-Oct 1987 using a moored array of instruments (see Dickey et al., this volume). A subset of these data, the spring deployment (the first of three) from March to mid May, has been analyzed with respect to the diel phase variations in the bio-optical properties. Among the features noted, the relationship between PAR and chl-fl changed from chl-fl lagging the PAR signal by ca 90 degrees, through 180 degrees of shift to leading by approximately 90 degrees. The transition period corresponding to this change was marked by inconsistent behavior in the phase relationships between other bio-optical variables, but the changes were short-lived and returned to their previous offsets from the daily PAR. These changes are thought to be the result of a succession of species caused by a combination of warm outbreaks of Gulf Stream waters importing a foreign particle assemblage into the Sargasso Sea, contemporaneous with wind events causing deep mixing. This hypothesis is consistent with recent observations at sea and in laboratory studies.

Original languageEnglish (US)
Pages (from-to)214-224
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 1990
Externally publishedYes
EventOcean Optics X - Orlando, FL, USA
Duration: Apr 16 1990Apr 18 1990

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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