Euphotic Zone Depth: Its Derivation and Implication to Ocean-Color Remote Sensing

ZhongPing Lee, Alan Weidemann, John Kindle, Robert Arnone, Kendall L. Carder, Curtiss Davis

Research output: Contribution to journalArticlepeer-review

Abstract

<p> Euphotic zone depth, <em> z </em> <sub> 1% </sub> , reflects the depth where photosynthetic available radiation (PAR) is 1% of its surface value. The value of <em> z </em> <sub> 1% </sub> is a measure of water clarity, which is an important parameter regarding ecosystems. Based on the Case&hyphen;1 water assumption, <em> z </em> <sub> 1% </sub> can be estimated empirically from the remotely derived concentration of chlorophyll&hyphen;a ([Chl]), commonly retrieved by employing band ratios of remote sensing reflectance ( <em> R </em> <sub> rs </sub> ). Recently, a model based on water's inherent optical properties (IOPs) has been developed to describe the vertical attenuation of visible solar radiation. Since IOPs can be near&hyphen;analytically calculated from <em> R </em> <sub> rs </sub> , so too can <em> z </em> <sub> 1% </sub> . In this study, for measurements made over three different regions and at different seasons ( <em> z </em> <sub> 1% </sub> were in a range of 4.3&ndash;82.0 m with [Chl] ranging from 0.07 to 49.4 mg/m <sup> 3 </sup> ), <em> z </em> <sub> 1% </sub> calculated from <em> R </em> <sub> rs </sub> was compared with <em> z </em> <sub> 1% </sub> from in situ measured PAR profiles. It is found that the <em> z </em> <sub> 1% </sub> values calculated via <em> R </em> <sub> rs </sub> &hyphen;derived IOPs are, on average, within &sim;14% of the measured values, and similar results were obtained for depths of 10% and 50% of surface PAR. In comparison, however, the error was &sim;33% when <em> z </em> <sub> 1% </sub> is calculated via <em> R </em> <sub> rs </sub> &hyphen;derived [Chl]. Further, the importance of deriving euphotic zone depth from satellite ocean&hyphen;color remote sensing is discussed.</p>
Original languageAmerican English
JournalJournal of Geophysical Research - Oceans
Volume112
DOIs
StatePublished - Mar 16 2007

Keywords

  • euphotic depth
  • inherent optical properties
  • ocean‐color remote sensing
  • water clarity

Disciplines

  • Life Sciences
  • Marine Biology

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