Year-round discrete underway water column Chlorophyll a concentrations from the central Arctic

Near-daily concentrations of Chlorophyll a and phaeopigments from RV Polarsterns underway water supply system (inlet at 11m water depth) collected during legs 1,3,4, and 5 of the MOSAiC (PS122) drift expedition in the central Arctic Ocean. 2-4L of water were filtered onto pre-combusted GF/F filters (nominal pore size 0.7µm) and frozen at -80°C. Samples were subsequently extracted in 90°C acetone, homogenized using a cell mill, and measured on the following day using a Turner flourometer, followed by an acidification step to determine phaeopigments (see Knap et al. 1996 for details and calculations). Samples were collected from end of October 2019 to beginning of October 2020, with a gap between mid-December and the end of February.