• Radiation components:
  • Global Horizontal Irradiation (GHI): ghi.h5
  • Beam (direct) Horizontal Irradiation (BHI): bhi.h5
  • Diffuse Horizontal Irradiation (DHI): dhi.h5
  • Beam (Direct) Normal Irradiation (BNI): bni.h5
  • Global Horizontal Irradiation in clear sky conditions (Gc): gc.h5
  • Beam (direct) Horizontal Irradiation in clear sky conditions (BHI): bc.h5
  • Diffuse Horizontal Irradiation in clear sky conditions (DHI): dc.h5
  • Beam (Direct) Normal Irradiation in clear sky conditions (BNI): bnc.h5
• Time step: 15 minute
• Temporal period: 2005 to 2016
• Format: hdf5
• 7z compressed

We used a nb_lines*nb_columns = 385*370 points over Africa with a 0.2° step. Only grid cells on land were computed.

• grid_step = 0.2°
• minimum longitude: -20°
• minimum latitude: -37°
• maximum longitude: 54°
• maximum latitude: 40°

NB: the formula to convert (lat, lon) into grid cell is:

• x = round((lon - lon_min)/grid_step + 0.5)
• y = round((lat_max - lat)/grid_step + 0.5)

Each HDF5 dataset comprises 420768 maps. 420768 is the number of 15 min periods from 2005-01-01 to 2016-12-31: 96 periods per day * 365 days * 12 years + 96 * 3 days (for 2008, 2012 and 2016 leap years).

Each value in HDF5 files is stored as an unsigned byte:

• The value 255 denotes a grid cell over the sea (not computed)
• The value 254 means a computation error
• Else, the value should be multiplied by 1.2 to get the 15 min GHI irradiation in Wh/m².

If you extract ghi.h5 data as a time series for one location, you will get almost the same data as CAMS Radiation web interface. The small difference is due to the data compression as 1 byte per value in JADE.