Phytoplankton absorption during SONNE cruise SO218

Water samples were collected from the two-week SO218 SHIVA-Sonne cruise which covered a transect from Singapore (1.26 N, 103.82 E) to Manila (14.59 N, 120.97 E), crossing the shelf areas of both South China Sea (SCS) and Sulu Sea (SS), and the deep water basin in the SS. Wtaer samples were taken from the ship's moonpool during underway and from CTD Niskin bottles at six different depths from the upper 150 m during CTD station. An additional sampling of surface waters at 1, 5, and 10 m were carried out at two near shore stations by local small boat. For locations of underway, local and CTD stations see Fig. 1 in Cheah et al. 2013. All collected samples were filtered through 25 cm Whatman GF/F filters, respectively, under low-vacuum pressure (below 200 mbar), and then immediately shock-frozen in liquid nitrogen and stored at −80°C for later analysis in the lab. Measurements of the phytoplankton absorption were carried out on a dual-beam UV/VIS spectrophotometer (Cary 4000, Varian Inc.) equipped with a 150 mm integrating sphere (external DRA-900, Varian, Inc. and Labsphere Inc., made from Spectralon (TM)) using a quantitative filterpad technique modified as described in details in Taylor et al. (2011). The data set is also collocated to Bracher (2014) phytoplankton pigment data and Bracher et al. (2021) particulate absorption data.