Impact of phytoplankton community size on a linked global ocean optical and ecosystem model
Impact of phytoplankton community size on a linked global ocean optical and ecosystem model
Date
2011-01
Authors
Mouw, Colleen B.
Yoder, James A.
Doney, Scott C.
Yoder, James A.
Doney, Scott C.
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Date Created
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Keywords
Phytoplankton cell size
Chlorophyll
Remote sensing reflectance
Ecosystem modeling
Optics
Global ocean
Chlorophyll
Remote sensing reflectance
Ecosystem modeling
Optics
Global ocean
Abstract
We isolated the effect phytoplankton cell size has on varying remote sensing reflectance
spectra (Rrs(λ)) in the presence of optically active constituents by using optical and radiative
transfer models linked in an offline diagnostic calculation to a global
biogeochemical/ecosystem/circulation model with explicit phytoplankton size classes. Two case
studies were carried out, each with several scenarios to isolate the effects of chlorophyll
concentration, phytoplankton cell size, and size-varying phytoplankton absorption on Rrs(λ).
The goal of the study was to determine the relative contribution of phytoplankton cell size and chlorophyll to overall Rrs(λ) and to understand where a standard band ratio algorithm (OC4) may
under/overestimate chlorophyll due to Rrs(λ) being significantly affected by phytoplankton size.
Phytoplankton cell size was found to contribute secondarily to Rrs(λ) variability and to amplify
or dampen the seasonal cycle in Rrs(λ), driven by chlorophyll. Size and chlorophyll were found
to change in phase at low to mid-latitudes, but were anti-correlated or poorly correlated at high
latitudes. Phytoplankton size effects increased model calculated Rrs(443) in the subtropical ocean during local spring through early fall months in both hemispheres and decreased Rrs(443)
in the Northern Hemisphere high latitude regions during local summer to fall months. This study
attempts to tease apart when/where variability about the OC4 relationship may be associated
with cell size variability. The OC4 algorithm may underestimate [Chl] when the fraction of
microplankton is elevated, which occurs in the model simulations during local spring/summer
months at high latitudes in both hemispheres.
Description
Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 89 (2012): 61-75, doi:10.1016/j.jmarsys.2011.08.002.