Description: Data include area fractions of sea ice surface types (white ice/snow, bright melt ponds, dark melt ponds, open water, bare ice) obtained from aerial imagery during 29 research flights that were performed within the scope of the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment from May 2020 until end of September 2020. The images were taken every four seconds by fisheye lens cameras (Canon EOS digital) installed on a helicopter or HELiPOD, a towed survey probe. The data set provides additional information about the attitude and geographic location of the helicopter/HELiPOD. Only images that passed the quality checks were included.

Description: During the MOSAIC expedition, we deployed in-ice light measuring buoys, lightharp, and lightchains into the ice to investigate light partitioning and irradiance at different layers and depths in sea ice. The dataset presented here contains processed data from both instrument systems, containing derived optical properties, PAR data, and auxiliary data for each deployment site. Auxiliary data gives information on the position, snow, and ice thickness statistics, and surface melt that changes the relative vertical position of the measurements. Auxiliary data was retrieved from SIMBA buoys deployed in the vicinity of the optical instruments. All data are provided in NetCDF format. The dataset includes processed data from the lightharp and three light chains (one redeployed on Leg5) from MOSAiC. The instruments were deployed at four different sites during MOSAiC: LM site (SYI dark coring site), L3 site, Pond site on Leg5 and within the Central Observatory (CO). The first part of the filenames reflects the deployment site. The second part gives the buoy name to which the optical sensors were connected and the last part the measurement period in YYMMDD. The NetCDF files were compiled using the profile_trajectory standard from CF conventions. Multiple directly measured and derived data layers are included with data coordinates depth and nominal_date. Nominal_date is the time of the uppermost valid measurement of a profile. Furthermore, files contain a set of already published auxiliary data describing the snow- and ice thickness statistics at the measurement sites (mean, max, min, and std) and a proxy for surface melt, that changes the vertical position of the frozen-in sensors. The lightharp data furthermore contains snow thickness from SIMBA buoy T62 and an individual surface melt approximation derived with temperature measurements at the optical sensors and surface melt rates. Data PIs and further helpful information is included in the attributes.