SeaFlow is an underway flow cytometer designed to continuously monitor the optical properties of the smallest phytoplankton from a ship's flow-through seawater system. It collects high-resolution data, generating the equivalent of 1 sample every 3 minutes or every 1 km (for a ship moving at 10 knots). The dataset provides measurements of cell abundance, cell size (equivalent spherical diameter) and carbon biomass for small phytoplankton populations: the cyanobacteria Prochlorococcus, Synechococcus, Crocosphaera, and small eukaryotic phytoplankton (<5 μm ESD). Data processing followed the methods outlined in Ribalet et al. (2019). For more information, visit the SeaFlow website. New in version 1.6 The updated dataset includes flow cytometric measurements from 89 cruises, spanning nearly 14,000 hours of observations across 130,000 km of the surface oceans.

This work was supported by grants from the Simons Foundation (#574495 to FR, #329108 to EVA and AEW, and #426570SP and #549894 to EVA), the Gordon and Betty Moore Foundation (#3776 to EVA) and the National Aeronautics and Space Administration (#80NSSC17K0561 to FR)