Solar radiation over and under sea ice was measured by radiation station 2018R2, an autonomous platform, installed on land fast ice in the Lincoln Sea, Arctic Ocean during Alert_MAPLI18. The resulting time series describes radiation measurements as a function of place and time between 08 May 2018 and 18 June 2018 in sample intervals of 1 hour. The radiation measurements have been performed with spectral radiometers. All data are given in full spectral resolution interpolated to 1.0 nm, and integrated over the entire wavelength range (broadband, total: 320 to 950 nm). Two sensors, solar irradiance and upward reflected solar irradiance, were mounted on a on a platform about 1 m above the sea ice surface. The third sensor was mounted 0.5 m underneath the sea ice measuring the downward transmitted irradiance. All times are given in UTC.