missing days of data due to Meteosat failures - missing days of data due to sun elevation - missed slots of data but interpolated in HelioClim-3 service

The missing value is -999. When you retrieve HelioClim-3 time series, you receive missing values ONLY IF THE WHOLE DAY OF DATA IS MISSING. If at least one Meteosat image has been collected in a given day, all the 15 minute values are interpolated.

Two reasons cause a full missing day:

• either an Eumetsat service failure: maintenance on the satellite, outage in the slot transmission...
• or the sun elevation is below 12°, which is our threshold below which the HelioClim-3 data are not computed.

In any case, pay attention to discard the -999 values in the SoDa output CSV file retrieved via one of the HelioClim-3 services. If you forget, summing up the columns in your file will lead to incorrectly low values.

List of missing days of data due to Meteosat failures

List of missing days due to sun elevation threshold (below 12°)

Validations of the Heliosat-2 method showed an increased error when the sun elevation angle is low. In order to avoid inaccurate data, Helioclim-3 does not compute data when the sun elevation is below 12 degrees.

The picture above shows the number of days with missing values (-999) in northern Europe. More than 100 days with missing values (-999) in the high latitudes!

List of missed slots of data but interpolated in HelioClim-3 service

The reasons for missing a slot of data are numerous: local electrical or network failure, problem on the satellite or at Eumetsat during the slot transfer... In this last case, Eumetsat emits a warning issue, and the images can not be retrieved by any mean.

You can find information on the missing Meteosat images on this website (filters ⇒ predefined ⇒ Meteosat 0 degree).