POC: 500 mL seawater was filtered from depths above 100 m. One L seawater was filtered for depths below 100 m. All seawater samples were filtered gently via vacuum (<10 mm Hg) through 25 mm (0.7 µm) Whatman GF/F filters that were precombusted at 450˚C for 4 hours. Filters were folded in quarters and stored in pre-combusted (450˚C for 4 h) glass scintillation vials. Samples were stored at -20˚C until analysis at the UC Santa Barbara Marine Science Institute Analytical Lab on an Automated Organic Elemental Analyzer following the Dumas combustion method.

Nutrients: 40 mL of seawater was directly filtered from the Niskin bottle through a 0.8 µm polycarbonate filter housed in a 47 mm polycarbonate filter holder into a sterile 50 mL conical centrifuge tube. Samples were stored at -20˚C until analysis at the UC Santa Barbara Marine Science Institute Analytical Lab via flow-injection analysis on a QuickChem 8500 Series 2.

HPLC: Approximately 2 L seawater was filtered through 25 mm (0.7 µm) Whatman GF/F filters. Filters were folded in half, stored in foil packets, and put immediately in liquid nitrogen, where they were kept through shipment to and until analysis at NASA Goddard Space Flight Center. HPLC pigments were analyzed by Crystal Thomas following Van Heukelem and Thomas (2001): https://oceancolor.gsfc.nasa.gov/fsg/hplc/

Quality flags reflect those used by the World Ocean Circulation Experiment (WOCE):
1: sample taken
2: acceptable measurement
3. questionable measurement
4. bad measurement
5. not reported
9. no sample drawn