Hyperspectral underwater light field measured during the cruise MSM21/3 with RV MARIA S MERIAN

Data presented here were collected during the cruise MSM21-3 with MARIA S MERIAN from Nuuk, Greenland to Reykjavik, Iceland (July 25th, 2012 - August 10th, 2012). In total, 82 underwater light profiles were collected at 41 stations (at least three repilcates each), using a free-falling hyperspectral light profiler. The system used was a Sea-Bird HyperPro II (SN 099, former Satlantic), equipped with a irradiance sensor to measure downwelling irradiance (Ed, SN 262) and a radiance sensor for upwelling radiance (Lu, SN 227). A reference unit was attached to the ship to measure the above water irradiance (Es, SN 263). The sensors were pre-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 data to Level 1, 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 minimum, maximum, 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.