Absorption coefficients by coloured dissolved organic matter from North Sea to Fram Strait measured at fixed stations with a Liquid Waveguide Capillary Cell system during POLARSTERN cruise PS99.1

Water samples were taken during North Sea to Fram Strait expedition PS99.1 with RV Polarstern from 14 to 23 Jun 2016. Water samples were collected from CTD Niskin bottles at five to six different depths from the upper 100 m. The same water samples were measured as in Liu et al. (2021). Water samples for CDOM absorption analysis were filtered through 0.2 µm filters and analysed onboard with a 2.5-m path length liquid waveguide capillary cell system (LWCC, WPI) following Levering et al. (2017). Details on method adaptation to our instrumentation set-up are provided in Alvarez et al. (2022). Salinity data were taken using SeaBird 911-plus CTD (Conductivity-Temperature-Depth) mounted on the SBE 32 Carousel Water Sampler (Rosette) equipped with 24 Niskin Bottles (12-L capacity). CTD data were also quality checked using salinity measured from water samples and analysed in laboratory with Autosal Salinometer Guildine 8400B. Extrapolated data were used from CTD downcasts based on data at depths were also water samples were taken.