Meteorological annotation processing computes the meteorological parameters, time-sorted and co-located with the tie-point grid given at a resolution of 16 km across-track and 1km along-track, in order to enable further processing at Level-2. Firstly, it applies a temporal interpolation between the values available before and after the mid-exposure time of the product. Secondly, a spatial bilinear interpolation is applied on each tie-point location to retrieve all parameters of interest on this grid.

Some Meteorological parameters are directly provided from the time series ECMWF files, i.e. without interpolating the data at the mid product time. These parameters are provided at 5 different times (-18, -12, -6, 0, 6) in hours since the single ECMWF time field.

Before this step, a tie-point interpolation is performed. This processing has two main objectives:

• Delimit the rectangular SLSTR Level-1B image
• Go from 16 km resolution to 1 km resolution in the along-track direction for the tie-point grid