Solar radiation over and under drifting sea ice was measured using RAMSES hyper-spectral radiometers (TriOS) mounted on the remotely operated vehicle (ROV) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) between November 2019 and September 2020. All data are given in full spectral resolution interpolated to 1.0 nm, integrated over the entire wavelength range (broadband, total: 320 to 950 nm), and integrated over the photosynthetically active radiation wavelength range (PAR: 400 to 700 nm). Two sensors were mounted on the ROV, an irradiance sensor (transmitted solar irradiance, ACC: Advanced-Cosine-Collector) for energy budget calculations and a radiance sensor (transmitted solar radiance, ARC: Advanced-Radiance-Collector with a 7° opening angle) to obtain high-resolution spatial variability. One additional radiometer was installed on the sea ice for surface reference measurements (incident solar irradiance, ACC). This is a raw data set, including all recorded spectra without any selection. Along with the radiation measurements, ROV positions were obtained from an acoustic Long Base Line (LBL) positioning system (LinkQuest Pinpoint). ROV depth was measured by a pressure sensor (Keller A-21Y, Keller AG). All times are given in Universal Coordinated Time (UTC).

Version comment (version 2.0):• More accurate position (X, Y) and depth values have been included.• The depth values have been adjusted for pitch and roll of the ROV.• Very high, physically not meaningful broadband transmittance and transflectance values have been included in some winter surveys to achieve uniform file structure. Very high, physically not meaningful values arise from dividing very low values (transmitted irradiance and radiance values during winter) by even lower values (incident irradiance values in winter) and integrating over the solar spectrum (320 nm to 950 nm).• Mismatches between some files and corresponding dates have been sorted correctly.