Implement time difference for instantaneous SARAHx products
[Context]
When using SARAHx or other external products, PVGIS retrieves the original timestamps from (one of) the input space-time data which are then used for the calculations.
Note, PVGIS expects and assumes that all external data are temporally identical. In case of a difference in the timestamps between the external products read to perform the calculations (i.e. SIS and SID from the SARAHx climate data records), an error raised to break the calculations.
Required adjustment
The main function to apply the SEVIRI time difference is :
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The scan time for a SEVIRI image that consists of 3712 pixels in geographic coordinates, is 12 minutes.
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The following pseudo-code describes a function of the number of line (row that corresponds to the geographic latitude) can be used to apply the time difference :
time shift in minutes = ( 3712 - line ) * 12 / 3712
References