Phytoplankton Productivity

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Phytoplankton Productivity Along CalCOFI line 67
LT Robert Witzleb Operational Oceanography OC3570
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Measurements (Data)
Sea-Viewing Wide Field of View Sensor (SeaWiFS)
(mg Chlorophyll/m3)
Chelsea Aquatracka III Fluorometer
(volts)
In Situ Chlorophyll concentration via
non-combusted GFF filtering and acetone
extraction of pigment
(mg Chlorophyll/m3)
Primary productivity via 14C assimilation during
controlled incubation
(mg Chlorophyll/m3/day)
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Two data sets exploited April and
September of 2000
Seven CalCOFI stations and C1 consistent between
cruises.
Standard depths analyzed (0,5,10,20,30,40,60,80,10
0,150, and 200 m). Fluorometer available
every 2 m.
Productivity throughout euphotic zone (LPDs of
100, 50, 30, 15, 5, 1, .1)
For depth integrated values, a sum of euphotic
zone values were used.
SeaWiFS composites used for months in question
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CalCOFI Line 67
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CalCOFI Line 67
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April 2000 Composite
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September 2000 Composite
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Chlorophyll A versus Fluorometer
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Table 1. Statistical analysis of in situ
collected chlorophyll a (mg/m3) as the dependent
variable and CTD rosette mounted
fluorometer output (volts) as the independent
variable for two cruises conducted
along CalCOFI line 67 during 2000.
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SeaWiFS vs Other Data
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Table 2. Correlation between the various in situ
data and SeaWiFS derived chlorophyll a
concentrations.
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Carbon Uptake versus Chlorophyll/Fluorometer
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Table 3. Correlation of 14C uptake (mg/m3/day)
to in situ chlorophyll a
(mg/m3) and fluorometer output
(volts).
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GOODS
OTHERS
SeaWiFs is a good approximation for productivity
including coastal regions.
Chlorophyll is only one ingredient to
productivity.
The fluorometer can be used effectively
to estimate chlorophyll concentration.
The fluorometer measures a photosystem
mechanism that differs from that of primary
productivity (competing processes).
On a global scale, remote sensing techniques are
the appropriate tool. In situ data may only
serve to calibrate satellite data.
The high variability (spatial and temporal) of
primary productivity creates sampling resolution
issues.
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April 2000 SST
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September 2000 SST