A Phytoplankton Class-Specific Marine Primary Productivity Model Using MODIS Data

The phytoplankton pigment absorption (a
_ph
)-based productivity model (AbPM) is commonly used to estimate marine net primary production (NPP). In the AbPM, a
_ph
is used as the key predictor of phytoplankton photosynthetic efficiency. Previous studies have shown that the size of phytoplankton could affect the photosynthetic efficiency. Thus, a size-fractionated AbPM was proposed by considering how phytoplankton size influenced the global quantum yield of phytoplankton photosynthesis. The sea surface temperature (SST) was also used to further improve AbPM performance in cold waters (SST <; 10 °C). With the proposed new model, monthly averaged global ocean NPP data for the period 2003-2012 were derived, and the distributions of the global NPP differed in both space and time from previous AbPM-based estimates. The accuracy of the new estimated model was validated using in situ NPP data, which were collected from different marine monitoring sites. Compared with the original AbPM, the new model not only had an excellent performance at each marine monitoring site, but also had an improved accuracy over the Southern Ocean. Although additional studies need to be conducted for confirmation, this size-fractionated model could be a reasonable and accurate method for the estimation of global ocean NPP.