Gridspec

A gridspec describes spatial grids in the form a dict. Its specification is yet to be finalised. However, at the moment, only the grid key has to be used for the source and target grids earthkit-regrid supports.

The grids supported by earthkit-regrid and their gridspecs are summarised below:

global octahedral reduced gaussian grid

The grid format is:

OXXX

where XXX is the number of latitude lines between the pole and equator. For details about this grid, see here.

Example:

{"grid": "O320"}

global (non-octahedral) reduced gaussian grid

The grid format is:

NXXX

where XXX is the number of latitude lines between the pole and equator. For details about this grid, see here.

Example:

{"grid": "N320"}

global regular latitude-longitude grid

The grid format is:

[DLON, DLAT]

where DLON and DLAT are the increments in degrees in longitudes and latitudes, respectively. This grid definition uses the default scanning mode used at ECMWF: values start at North-West and follow in consecutive rows from West to East, where West is always the 0° meridian.

Example:

{"grid": [1, 1]}

HEALPix nested grid

The grid format is:

HXXX

The order must be set to "nested". For details about this grid, see here. For backward compatibility the ordering key is still accepted as an alias for order.

Example:

{"grid": "H512", "order": "nested"}

HEALPix ring grid

The grid format is:

HXXX

The order can be omitted or set to "ring". For details about this grid, see here. For backward compatibility the ordering key is still accepted as an alias for order.

Example:

{"grid": "H512", "order": "ring"}
{"grid": "H512"}

ORCA grid

The grid format is:

eORCAXXX_subtype

The subtype must be “T”, “U”, “V” or “W”.

Example:

{"grid": "eORCA025_T"}