Friedrichs, Anna; Schwalfenberg, Kai; Voß, Daniela; Wollschläger, Jochen; Zielinski, Oliver (2020): Hyperspectral underwater light field measured during the cruise MSM56 with RV MARIA S. MERIAN [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.917534

Data presented here were collected during the cruise MSM56 with MARIA S MERIAN from Longyearbyen, Svalbard to Reykjavik, Iceland (July 2nd, 2016 - July 25th, 2016). In total, 133 underwater light profiles were collected at 68 stations (with at least three repititions), using a free-falling hyperspectral light profiler. The system used was a SEABIRD HyperPro II (SN 143, former Satlantic), equipped with a irradiance sensor to measure downwelling irradiance (Ed, SN 392) and a radiance sensor for upwelling radiance (Lu, SN 323). A reference unit was attached to the ship to measure the above water irradiance (Es, SN 393). The sensors were pre-calibrated by the manufacturer. 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 MSM56: Dr. Koch, B. P., Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research