Primary Productivity (netPP) Algorithm
The Behrenfeld and Falkowski (1997) algorithm estimates primary productivity using satellite measurements and derived parameters. The algorithm formulation is listed below:
\(netPP = 0.66125 \times P_{opt}^b \times \frac{PAR^o}{PAR^o + 4.1} \times Z_{eu} \times CHL \times DL\)
Satellite Measurements
The algorithm uses three satellite measurements:
- CHL - Surface Chlorophyll a Concentration
- PAR - Photosynthetically Active Radiation
- Sea Surface Temperature
Derived Parameters
The derived parameters are:
-
\(P_{opt}^b\) - Maximum Carbon fixation rate within the water column - Units: \(mg\) \(C\) \(mg^{-2}\) \(chl\) \(h^{-1}\) :
\(P_{opt}^b = - 3.27E-8 \cdot SST^7 + 3.4132E-6 \cdot SST^6\)
\(- 1.348E-4 \cdot SST^5 + 2.462E-3 \cdot SST^4\)
\(- 0.0205 \cdot SST^3 + 0.0617 \cdot SST^2 + 0.2749 \cdot SST\)
- \(PAR/(PAR + 4.1)\) - Relative change in the light-saturated fraction of the euphotic zone.
-
\(Z_{eu}\) - Depth where light is 1% of that at the surface - Units: meters (m)
\(Z_{eu}\) is derived from an estimate of the total chlorophyll concentration within the euphotic layer (\(CHL_{eu}\)) based on the Case I models of Morel and Berthon (1989):
\(Z_{eu} = 568.2 \cdot CHL^{-0.746} \quad \text{when } CHL_{eu} > 10.0\)
or
\(Z_{eu} = 200.0 \cdot CHL^{-0.293} \quad \text{when } CHL_{eu} \leq 10.0\)
Where:
\(CHL_{eu} = 38.0 \cdot CHL^{0.4250} \quad \text{when } CHL \leq 1.0\)
or
\(CHL_{eu} = 40.2 \cdot CHL^{0.5070} \quad \text{when } CHL > 1.0\)
- DL - Daylength determined from the day of the year and latitude - Units: hours
