The subtropical gyres occupy about 70% of the ocean surface. While
primary production (PP) within these oligotrophic
regions is relatively low, their extension makes their total contribution to ocean productivity significant.
Monitoring marine pelagic primary production across broad spatial scales, particularly across the subtropical
gyre regions, is challenging but essential to evaluate the oceanic
carbon budget. PP in the ocean can be derived from
remote sensing however
in situ depth-integrated PP (IPP
is) measurements required for validation are scarce from the subtropical gyres. In this study, we collected >120 IPP
is measurements from both northern and southern subtropical gyres that we compared to commonly used primary productivity models (the Vertically Generalized Production Model, VGPM and six variants; the Eppley-Square-Root model, ESQRT; the Howard–Yoder–Ryan model, HYR; the model of MARRA, MARRA; and the Carbon-based Production Model, CbPM) to predict remote PP (PP
r) in the
subtropical regions and explored possibilities for improving PP prediction. Our results showed that satellite-derived PP (IPP
sat) estimates obtained from the VGPM1, MARRA and ESQRT provided closer values to the IPP
is (
i.e., the difference between the mean of the IPP
sat and IPP
is was closer to 0; |Bias| ~ 0.09). Model performance varied due to differences in satellite predictions of
in situ parameters such as
chlorophyll a (chl-
a) concentration or the optimal
assimilation efficiency of the productivity profile (P
Bopt) in the subtropical region. In general, model performance was better for areas showing higher IPP
is, highlighting the challenge of PP prediction in the most oligotrophic areas (
i.e. PP < 300 mg C m
−2 d
−1). The use of
in situ chl-
a data, and P
Bopt as a function of
sea surface temperature (SST) and the mixed layer depth (MLD) from
gliders and floats in PP
r models would improve their IPP predictions considerably in oligotrophic oceanic regions such as the subtropical gyres where MLD is relatively low (<60 m) and cloudiness may bias satellite input data.