Eye2Sky dataset - All-sky images and meteorological measurements

Eye2Sky dataset - All-sky images and meteorological measurements 

Description

The Eye2Sky public dataset comprises all-sky images from 29 All-Sky Imager (ASI) stations and meteorological measurements including solar irradiance from 11 stations in north-west Germany. A list of all stations with meta information is provided in the attached Eye2Sky_Station_List.xlsx

Meteorological measurements cover a full year from April 2022 to March 2023 with minutely averaged parameters. Parameters measured are three solar radiation components global horizontal, diffuse horizontal and direct normal irradiance. Global tilted irradiance is measured with tilt angles of 30° in southern direction. Measurement data has been quality controlled. Raw data is provided along with quality flags.  For users who want to use measurements directly, a "ready-to-use" data set with cleaned data is provided.

ASI images of the whole ASI network at all stations cover a 4-month period from April to July 2022 with 30 seconds sampling rate, for station OLUOL the dataset covers a full year from April 2022 to March 2023 to allow season-dependent analyses at a central location inside the ASI network. The sampling rate for OLUOL is 15 seconds (since 2022-06-10). Images are provided as raw data (jpg-format), but calibration information and horizon masks are provided as meta data. Note: Due to maximum upload size allowed by Zenodo, only an example data set (ASI_20220620.zip) is provided here. The full set of ASI images can be downloaded from here: https://eye2sky.de/data

Quality flags for measurement data

Measurement data was quality checked using the procedure in attached image QC_Flowchart.png. The manual quality control refers to obvious measurement errors known to the station operator. Corresponding data is removed from the data set before additional tests are carried out on the data in an automatic quality control process. The tests performed are described in a publication in preparation.

Data Format

• All-sky images are provided as zipped archives in raw jpg-format (sampling 30 seconds).
  • Directory structure: One folder per day and station 
  • Meta data: each station folder consists of
    • a YAML-file providing meta data for each configuration change. The filename contains the timestamp of the latest change in configuration (could be a change in camera alignment or positioning). The file contains information on geographical coordinates, internal and external orientation and necessary mask file. 
    • image masks in binary png-files and mat-files. 
    • an example ASI image with an image mask overlay and image orientated to geographic north according to calibration parameters
    • a keogram composite of all ASI images in the full data period.
• Measurement data is provided in zipped station directories.
  • There are two files of timeseries data for each station and for the full time period.
    • data/STATION_ID.flagged.nc contains raw data including QC-flags
    • data/STATION_ID.cleaned.nc contains cleaned data 
  • Meta data: For each station
    
    • a horizon file for the near horizon near_horizon.csv
    • and a log file of changes and quality check report is provided: QC_{STATION_ID}.pdf
• Ceilometer data for Stations CDLRA (Oldenburg) and CLDRB (Westerstede) is provided in daily netcdf-Files. 
  • Timeseries plots of daily measurements are attached for both stations.

VERSION UPDATES

Version 1.0:

• Initial Upload

ACKNOWLEDGEMENTS

DLR Institute of Networked Energy Systems is responsible for the construction, operations, quality control and scientific evolution of the Eye2Sky network. DLR Institute of Solar Research was involved in designing the network and strongly supports Eye2Sky with software for data acquisition, calibration, processing and evaluation. We would like to thank all DLR staff who helped with the procurement of funding, installation support, data acquisition and data quality control. We also thank all persons, institutions and companies who contributed to the installation and who offered hosting a station.

LICENSE

- All the All-Sky images are licensed under CC-BY-SA 3.0.
- All the measurement data from meteorological stations and ceilometers is licensed
under the CDLA 1.0 sharing license: https://cdla.dev/sharing-1-0/.