Particulate absorption during RV Sonne expedition SO235

Water samples were taken during the expedition OASIS (Organic very short lived substances and their Air–Sea exchange from the Indian Ocean to the Stratosphere) cruise (S0235) in the Indian Ocean on board the R/V Sonne I from Port Louis, Mauritius, to Malé, Maldives from 23 July to 6 of August 2014 (see Fig. 1 in Booge et al. 2018). Water samples were collected from ship's moonpool during underway and from CTD Niskin bottles at six different depths from the upper 150 m. 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. Measurement for total particulate matter absorption spectra between 350 to 800 nm were carried out using a Cary 4000 UV/VIS dual beam spectrophotometer equipped with a 150 mm integrating sphere (Varian Inc., USA). The method is described in details in Taylor et al. (2011). The data set is also collocated to Bracher et al. (2019) phytoplankton pigment data.