Dataset: Pigment concentrations determined by HPLC from samples collected on Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018

Pigments were sampled from the shallowest 6 depths (<=150 meters) on every "PigRaTh" cast (including the surface bottle) at all major stations (N=23 stations). Pigments were collected into 2-liter (L) amber bottles, triple-rinsed with sample prior to filling. They were immediately filtered under vacuum through 47-millimeter (mm) GF/F filters. They were folded and placed inside cryovials, labeled with appropriate GEOTRACES numbers, and frozen at -80° Celsius (C). Vials were shipped in LN2 dry shippers to Stanford, and then on dry ice to the HPLC Facility at Oregon State University (OSU) managed by Ricardo Letelier (https://ceoas.oregonstate.edu/ocean-ecology-and-biogeochemistry-facilities).

OSU HPLC facility methods: Our method for pigment analysis is based on the protocol described by Mantoura and Lewellyn (1983) and modified according to Bidigare et al. (1989). Briefly, samples are extracted for up to 48 hours in 100% acetone at -20°C, then analyzed on a Waters 2690 separations module equipped with a C18 column and full spectrum photodiode array detector. Pigment standards for calibration and response factor calculations are obtained from DHI Group in Denmark.