Algorithm Theoretical Basis Document forPrimary Production and Red Tide Algorithm for SGLI/GCOM-C(Ver. 1.0)

Joji Ishizaka
Hydrospheric Atmospheric Research Center
Nagoya University
March 19, 2011

I.

Introduction
Primary production and red tide are two important research products for

Second-generation Global Imager (SGLI) on Global Change Observation Mission –Climate (GCOM-C). This document briefly described those algorithms.
II. Primary Production Algorithm
The primary production algorithm is based on Vertically Generalized Production
Model (VGPM) developed by Behrenfeld and Falkowski (1997).

This model isexpressed as following;
IPP = 0.66125 PBopt PAR/(PAR+4.1) Zeu Chl Dirr
where IPP , PBopt, PAR, Zeu, Chl and Dirr is depth integrated primary production (mgCm-2 d-1), maximum chlorophyll-specific photosynthesis rate within a water column (mgC(mg Chl) -1 h-1), photosynthetically active radiation above the sea surface (mol quantam-2), depth of euphotic zone (m), chlorophyll-a concentration (mg m-3), and photoperiod(hr), respectively. Chl is originally defined to be the chlorophyll-a concentration at thedepth of PBopt; however, it is replaced to sea surface value which is calculated fromremote sensing reflectance. PAR is also input from other algorithm of SGLI. Dirr canbe calculated from Julian day and latitude.
PBopt is originally defined by 7th order polynomial function of T (sea surfacetemperature, oC); however, Kameda and Ishizaka (2005) redefined with a function of Tand Chl assuming two phytoplankton community.
PBopt = 0.071 T – 3.2x10-3 T2 + 3.0x10-5 T3)/Chl+ (1.0 + 0.17 T – 2.5x10-3 T2 – 8.9x10-5 T3)
Zeu should be used calculated value by other algorithm of SGLI; however originallyused and coded as the functions of Morel and Berthon (1989) which is only applicable toCase I water.
Behrenfeld, M. and P. Falkowski (1997) Photosynthetic rates derived fromsatellite-based chlorophyll concentration. Limnol. Oceanogr. 42, 1-20.
Kameda, T. and J. Ishizaka (2005) Size-fractioned primary production estimated by a
two-phytoplankton community model applicable to ocean color remote sensing, J.
Oceanogr. 6, 663-672.

Morel, A. and J.-F., Berthon (1989) Surface pigments, algal biomass profiles, andpotential production of the euphotic layer: Relationships reinvestigated in view ofremote-sensing applications. Limnol. Oceanogr., 34, 1545-1562.
III. Red Tide Algorithm
Detail of the red tide algorithm can be found attached unpublished manuscript. It
is based on sequence of steps to discriminate normalized water leaving radiance (nlw)
spectral shapes and identify the water type.

First step is to identify the peakwavelength of the nlw spectra and to discriminate clear water.

Second step is toidentify the curvature of the nlw spectra and to discriminate high suspended and/orcolored dissolved organic matter water. Third step is to compare the slope of nlw
spectra and chlorophyll-a concentration and to discriminate mixed water. In generalremaining condition indicate red tide condition. However, because high demand to
discriminate diatom and dinoflagellate, the algorithm further tests magnitude (fifthstep) and shape (sixth step) of the nlw spectra to distinguish two different diatom
groups and dinoflagellate.
This algorithm is developed to identify Karenia mikimotoi red tide off Ohita coast,and further study is required whether this algorithm works in other areas. It is also
noticed that the algorithm is developed based on MODIS data, and the wavelength isdifferent from SGLI.
wavelength.

It is further required to adjust the parameters for different