Voß, Daniela; Henkel, Rohan; Oelker, Julia; Badewien, Thomas Henry (2026): Downwelling irradiance Ed measured during the cruise MSM139 with RV MARIA S. MERIAN [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.995343 (DOI registration in progress),

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In: Voß, D et al. (2026): Hyperspectral underwater light field measured during the cruise MSM139 with RV MARIA S. MERIAN [dataset bundled publication]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.995340 (DOI registration in progress)

Data presented here were collected during the cruise MSM139 with MSM139 with RV Maria S. Merian from Reykjavik, Iceland to Reykjavik, Iceland (25.07 - 27.08.2025, working area Greenland). In total, 29 underwater light profiles were collected at 33 stations, using a free-falling hyperspectral light profiler. The system used was a SEABIRD HyperPro II (SN 189, former Satlantic), equipped with a irradiance sensor to measure downwelling irradiance (Ed, SN 532) and a radiance sensor for upwelling radiance (Lu, SN 421). A reference unit was attached to the ship to measure the above water irradiance (Es, SN 533). The sensors were calibrated by the manufacturer and validated prior to the cruise with a reference lamp. Data were recorded with the SatView software (V 2.9.5_7) and processed from raw to Level1, 1b, 2, 2s to Level 3a using the ProSoft Processing software (V 7.7.19_2). Measured data were binned in 0.5 m depth intervals. A dark correction was made automatically based on shutter measurements by the instrument. Measurements with a tilt higher than 5° were not taken into account during processing. Spectra were interpolated to 1 nm intervals. For each station the hyperspectral profiles for each parameter cover the wavelength range from 400-700 nm, for Ed and Es in [W/m² nm], for Lu in [W/m² nm sr]. For Ed, Lu and Es descriptive statistics are given including min, max, mean, median and standard deviation of the tilt and the photosynthetically active radiation PAR [µmol photons/m² s (sr)], integrated from 400 - 700 nm. Statistics are not given for profiles which do not reach the 1% PAR depth. To allow an assignment of above water conditions to the respective depth measurements, Es spectra were given as a function of depth, recalculated from data Level2s. The Profiler measurements were only conducted during daylight. Raw data are available on request from the principal investigator.

Chief Scientist of RV Maria S Merian cruise MSM139: Dr.Uwe John, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI).