Behrenfeld and Falkowski (1997a) compared measurements of Pbopt withtemperature (Fig. 3.10) and derived a single-factor empirical model for estimating the
maximum value of Chl-normalized photosynthesis in the water column:
(Eqn. 3.6) Fig. 3.10 Measured (•; ± SD) and modeled median value (solid curve) of the
photoadaptive parameter, PBopt, as a function of sea-surface temperature. Dashed
curve indicates the theoretical maximum specific growth rate (μ; d−1) of
phytoplankton described by Eppley (1972), which is used in a variety of productivity
models.
(^) (After Behrenfeld & Falkowski 1997a.)
The error bars based on measured values of Pbopt are wide and certainly contribute
to the uncertainty in the derived estimates of primary production, but the
approximation appears to be adequate to represent regional differences in maps of
global ocean productivity. Behrenfeld and Falkowski (1997b) also compared more
elaborate time-integrated, wavelength-integrated and wavelength-resolved models for
estimating primary production on global scales. The major difference among model
outputs derives from the mode of estimation of Pbopt, the “photoadaptive” variable.
When the same chlorophyll fields are used in the models, global annual primary
production in the ocean is about 44 Gt C yr−1.