N-ICE2015 particulate matter absorption spectra

Particle absorption coefficients (m-1) in seawater and sea ice. Samples were filtered onto 0.7 µm glassfiber filters and stored in -80 °C until analysis. Filters were measured between 240 and 800 nm with a Shimadzu UV-2450 dual-beam spectrophotometer with a Shimadzu ISR-2200 integrating sphere. Measurement was made before and after bleaching of pigments with 400 µl of sodium hypochlorite (NaClO) solution with 1 % active chlorine for 10 minutes. Additional 20 minutes was used if the first bleaching was not complete. Filters were rinsed with artificial sea water (60 g Na2SO4 in 1 L of ultrapure water). As wet reference an average of 20 filters (filtered with ultrapure water throughout the campaign) was used. A baseline correction was done relative to the mean absorption values at 750–800 nm. Method used follows the method by Tassan and Ferrari 2002 (https://doi.org/10.1093/plankt/24.8.757). More sampling details in Kauko et al. 2017 (https://doi.org/10.1002/2016JG003626), Pavlov et al. 2017 (https://doi.org/10.1002/2016JC012471) and Kowalczuk et al. 2017 (https://doi.org/10.1002/2016JC012589). Separate files for water column samples from ship CTD and on-ice CTD (mini-rosette), and for sea ice samples from different environments (thick second-year/first-year ice and young ice in a refrozen lead).