NCAVEO: Multi-angle sky spectra collected using a sky irradiance scanner

This dataset compromises measurements of the angular distribution of spectral sky radiance (400-1000nm), collected as part of the Network for Calibration and Validation of Earth Observation (NCAVEO) 2006 Field Campaign. Measurements were taken at frequent intervals on the 17th June 2006 using a new instrument designed by Andrew McGonigle. The instrument is based on a temperature-stabilised miniature spectroradiometer interfaced to a telescope that can be programmed to make zenithal scans of sky irradiance. Azimuthal motion of the whole instrument was provided by manual adjustment. A sampling interval of 18° in zenith and 30° in azimuth was used. All data were collected when the spectrometer was thermally stabilised to the same temperature (approximately 7.5°C). Each sample of the sky irradiance distribution comprised two scans: one of the whole sky, and then a second low-gain scan shortly afterwards, concentrating just on the region around the Sun. Scans were repeated twice, with different integration times to allow for the extreme differences in brightness of the Sun and the sky. For further information and details on the structure of the files see the dataset's metadata PDF in linked documentation.