Particulate absorption spectra (350-750 nm) measured in water samples collected in the Greenland Sea, during Atlantic-Arctic Ocean Change cruise (AOC2025) between 19-31 May 2025.

This data sets contains spectra of the light absorption coefficients of particles (ap(λ), m-1), detritus (ad(λ), m-1) and phytoplankton pigments (aph(λ), m-1) from samples collected during the Atlantic-Arctic Ocean Change cruise (AOC2025, Stedmon 2026) onboard of research vessel r/v Dana, between 19 - 31 May 2025. Its main goals were to collect a physical, chemical, and biological and geological observations of the Greenland Sea in five transect between Jan Mayen Island and East Greenland shelf break to marginal sea ice. Water samples were collected at three depths, near the surface, at the Subsurface Chlorophyll-a Maximum (SCM) and below it. The depth at which the SCM was located was determined from chlorophyll-a fluorescence profile measured by the standard fluorometer attached to the CTD rosette. Collected water samples were filtered onboard using Whatman filters (GF/F, 25 mm). Filters with the retained material were in deep frozen (-80 deg. C) and stored in these conditions until the measurements. Measurements were performed in the land based laboratory in the Institute of Oceanology Polish Academy of Sciences, Sopot, Poland, using a Perkin-Elmer Lambda 650 spectrophotometer equipped with an integrating sphere with a diameter of 15 cm. The spectra of light absorption coefficients were measured in the spectral range of 350-750 nm according to the methodology described by Tassan and Ferrari (1995, 2002) and Woźniak et al. (2011). Transmission and reflectance (T-R) measurements were performed for filters with suspended particles and again after bleaching with 2% sodium hypochlorite NaClO2 (Meler et al., 2020). To account for the optical path extension of light on the filter with suspension in relation to the same suspension in water, the beta factor correction was applied according to formulae developed by Stramski et al. (2015). This allowed to determine the spectra of the light absorption coefficient by all particles, ap(λ), as well as the absorption by bleached and mineral particles, (detritus - both organic and mineral), ad(λ). The light absorption coefficients by phytoplankton pigments aph(λ) were then calculated as the difference between ap(λ) and ad(λ).

Meler, J., Woźniak, S.B., and Stoń-Egiert, J.: Comparison of methods for indirectly estimating the phytoplankton population size structure and their preliminary modifications adapted to the specific conditions of the Baltic Sea, J. Mar. Sys, 212, 103446, https://doi.org/10.1016/j.jmarsys.2020.103446, 2020.

Stedmon, Colin; Böttner, Christoph; Dragańska-Deja, Katarzyna; Dutz, Jörg; Isobel Galen, Eve; Gjelstrup, Caroline Victoria Bratsbjerg; et al. (2026). Cruise report Atlantic-Arctic Ocean Change (AOC2025). Technical University of Denmark. Dataset. https://doi.org/10.11583/DTU.31972293

Stramski, D., Reynolds R.I., Kaczmarek, S., Uitz, J., and Zheng, G.: Correction of pathlength amplification in the filter-pad technique for measurements of particulate absorption coefficient in the visible spectral region. Applied Optics 54(22):6763-6782, https://doi.org/10.1364/AO.54.006763, 2015.

Tassan, S., Ferrari, G.M., 1995. An alternative approach to absorption measurements of aquatic particles retained on filters. Limnol. Oceanogr. 40(8), 1358–1368.

Tassan, S., Ferrari, G.M., 2002. A sensitivity analysis of the ’transmittance-reflectance’ method for measuring light absorption by aquatic particles. J. Plankton Res. 24(8), 757–774. https://doi.org/10.1093/plankt/24.8.757

Woźniak, S.B., Meler, J., Lednicka, B., Zdun, A., and Stoń-Egiert, J.: Inherent optical properties of suspended particulate matter in the southern Baltic Sea. Oceanologia 53(3):691-729, https://doi.org/10.5697/oc.53-3.691, 2011.