Nesting considerations

When driving model data is available at a resolution that is different to the target nest/resolution 1, the driving model is "reconfigured" onto the target nest/resolution 1. See the resolution (in degrees) of commonly used input datasets below.

dataset	resolution
ERA5	0.25°
BARRA-R2	0.11°
ERA5-land	0.1°
OSTIA	0.05°

Hence, choices in the driving model dataset affect nesting choices settings.

A pre-filled example based on ERA5 driving model with a 2.2km has been constructed with a double-level nest to enhance the accuracy of the run (by allowing the forecast model to "fill-in" some of missing details).

This has been down to allow for other higher quality reference datasets to be used to "replace" some of the driving model initial conditions. Hence, the double-nest allowed the opportunity to offer users to ability to use higher quality land/surface. Higher quality sea-surface temperature and sea-ice conditions can also be utilized.