HC3 missing data
HelioClim-3 missing data
Helioclim-3 missing data
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.
|5 and 6 October
|24 to 29 August
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!
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).