UiT�The Arctic University of Norway (UiT) and the Norwegian University of Science and Technology (NTNU) established a light observatory at Kings Bay, Ny-�lesund�(Svalbard, Norway) in January 2017. The observatory consists of an array of light sensors including an�all sky�camera. It is located outside the settlement of Ny-�lesund, approximately 1 km N-NW of the airport towards�Brandalspynten. The array of sensors is mounted on a tripod under a transparent dome. This dataset contains the data of the hyperspectral radiometer USSIMO�(In-situ Marine Optics, Perth, WA, Australia), converted to E(PAR) by the following equation:�PAR is approximated as an integral of�micromolespersec=(uirr/(hc/(lambda1e-9)))/microavo�for wavelengths(lambda) in range from 400 to 700nm, where:�uirr�= USSIMO irradiance for wavelength equal to lambda, h=6.63e-34 [Js], c=3.00e+08 [m/s],�microavo=6.022e17.�The sensor�is equipped with a Zeiss MMS1 UV-VIS NIR detector with National Institute of Standards and Technology, USA traceable radiometric calibration between 380 and 900 nm. This instrument is used for time-series measurement of down-welling spectral irradiance in energy Wm-2 nm-1. Spectral resolution is 10 nm (3.3 nm pixel spacing) and a cosine-corrected polytetrafluoroethylene (PTFE) light diffusor with cosine error: <3% (0 - 60�), <10% (60 - 87.5�), is fitted. The device acquired measurements with a�16 bit�analogue to digital converter.�It samples continuously internally. Integration time is controlled by the sensor depending on the light intensity, with a maximum of 6 seconds. Actual integration time is stored with the data in each sample.�The sensor output is saved on a PC with custom software which records 30 seconds of output data every 29:30 min. The number of samples collected in that period depends on the USSIMO integration time.�The sensor is equipped with a pitch and roll sensor which is used to ensure that the spectroradiometer remains in the fixed position throughout the time-series acquisition.�For re-use of the data, please refer to the dataset and the original publication.��This is the 2018 dataset. There is larger gap from 2018-10-28 09:00 to 2018-11-05 10:00 due to sensor failure.