SKYSPECTRA: an opensource data package for worldwide spectral daylight

SKYSPECTRA is an open-source data package comprising spectral daylight measurements collected from various sources worldwide. The dataset encompasses measurements from both long-term measurement sites and specific periods or experiments. 

Terms of use

For use of the dataset in research cite the paper titled skyspectra: an opensource data package of worldwide spectral daylight, presented at the CIE conference 2023, Slovenia, September 18-20 2023. The paper details the schema of the data package and will be publicly available soon.

Balakrishnan, P., Diakite-Kortlever, A., Dumortier, D., Hernández-Andrés, J., Kenny, P., Maskarenj, M., Pierson, C., Thorseth, A., Xue, P., & Knoop, M. (2023). SKYSPECTRA: An Opensource Data Package of Worldwide Spectral Daylight. In Proceedings of 30th session of CIE Conference, 15–23 September 2023. Ljubljana, Slovenia. DOI:10.25039/x50.2023.OP026

Funding 

This project is funded by the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Individual Fellowship (grant agreement No. 101032279)

Data availability 

Measurement data is between 360 nm to 800 nm wavelength

Timestamps with solar elevation angle equal to or above 15 degrees

Timestamps for two dates in the months of March, June, September, and December (when available)

Timestamps with clear and overcast sky conditions (when available)

Locations-Berlin, Beijing, Granada, Singapore, Vaulx en Velin (updates of other locations are ongoing) 

Data structure 

Measurement datasets include four data frames or tables in .csv format, each representing a distinct type of spectral daylight measurements.

spectral_horizontal_irradiance.csv: spectral irradiance measurements of global and diffuse visible radiation recorded on a horizontal plane

spectral_tilt_irradiance.csv: spectral irradiance measurements of global and diffuse visible radiation recorded on a tilted plane (not available currently)

spectral_patch_radiance.csv: spectral radiance measurements of visible radiation from patches of sky

spectral_direct_irradiance.csv: spectral irradiance measurements of visible radiation directly from the sun

Supplementary datasets include four data frames or tables in .csv format, each representing additional information for each measurement. 

meta_location.csv: information about the geographical location and immediate environment of where the measurements were taken

meta_weather.csv: information on sky conditions when the measurements were taken.

meta_sun_positions.csv: information about sun angles and true solar time when the measurements were taken.

meta_measurement_parameters.csv: information about specific measurement parameters used for each measurement.

Data collection

This data package contains a subset of the worldwide spectral daylight measurements collected to explore geographic variations in daylight spectral characteristics, an ongoing effort led by the CIE Technical Committee (TC 3-60). For more information on the data collection process and the templates used refer to the paper skyspectra: an opensource data package of worldwide spectral daylight mentioned above.