Gross and net primary production in the global ocean: An ocean color remote sensing perspective

Phytoplankton photosynthesis and organic matter production fuel marine ecosystems and provide the source material for trophic transfer and export to the ocean interior. Methods for directly measuring photosynthetic rates (both Gross and Net Primary Production, GPP and NPP) are limited in extent and not suitable for broad regional or global assessments. Satellite-based models for estimating GPP and NPP offer the most practical means to meet this need. A growing suite of models has proliferated over the last 25 years and helped shape our understanding of biological variability in the ocean, its role in elemental cycling, and feedbacks with the Earth climate system. This review documents efforts to model GPP and NPP from remote sensing measurements throughout the satellite ocean color era and highlights scientific findings from application of these approaches. In addition to discussing past milestones, we synthesize current state-of-the-art approaches and discuss similarities and differences in their global distributions of NPP or GPP. This review also covers published validation efforts to assess ensemble and model-specific accuracy and last, we provide a vision for future efforts that identifies remaining barriers to improving satellite estimates of GPP and NPP.