Gridspecs (for MIR)¶
A gridspec describes spatial grids in the form of a dict.
Warning
The gridspec format is not finalised yet and may change in future releases. Area specification is currently supported only as a provisional feature (subject to change or removal) and may emit deprecation warnings.
The gridspecs supported when regridding with the MIR backend are summarised below:
Gaussian grids¶
Gaussian grids are a family of global grids defined by the number of constant-latitude lines (parallels) between the pole and equator. Each parallel’s latitude is at Gaussian quadrature points so integrals can be calculated over the sphere. With increasing resolution these parallels approach but do not match the poles and equator. Longitudinally there are two descriptions: regular with constant number of points per parallel, and reduced with varying number of points per parallel, increasingly higher near the equator so as to approach a constant local horizontal resolution over the globe.
There are three patterns for grid, case-insensitive:
OXXX
NXXX
FXXX
where XXX is known as the Gaussian number, and represents the number of latitude lines between the pole and equator. For details about these grids, see here. The regular Gaussian grid, [Ff]XXX, has a constant number of points per parallel, while the reduced Gaussian grid, [NnOo]XXX, has a varying number of points per parallel.
There are a few pre-defined reduced Gaussian grids (eg. N160, N320, N640) which have a pre-defined number of points per parallel. The octahedral Gaussian grid ([Oo]XXX) has a specific number of points per parallel starting from 20 near the poles and increasing 4 points per parallel towards the equator, so it is defined for any Gaussian number.
Examples:
{"grid": "O320"}
{"grid": "o320"}
{"grid": "N320"}
{"grid": "n320"}
{"grid": "F320"}
{"grid": "f320"}
Regular latitude-longitude grids¶
The grid format is:
[DLON, DLAT]
where DLON and DLAT are the increments in degrees in longitudes and latitudes, respectively. This grid is global and includes the origin (0°, 0°), and the ECMWF’s default scan mode: first point at North-West with longitude the fastest index from West to East.
Example:
{"grid": [1, 1]}
{"grid": [0.1, 0.1]}
HEALPix grids¶
The grid is case-insensitive, in the format:
HXXX
HRXXX
HNXXX
The HEALPix grid is a global, hierarchical equal area isolatitude pixelisation of the sphere, where XXX is the HEALPix Nside representing the number of points per pixel side. There are 12 base pixels, so the total number of points is \(12 N_\mathrm{side}^2\). The points can be in ring (default) or nested order, indicated by the second letter or order (default ring); if the second letter is [Nn] or order is nested, the points order is nested. For details about this grid, see here.
Examples (the last two are in nested order):
{"grid": "Hr512"}
{"grid": "h512"}
{"grid": "H512", "order": "ring"}
{"grid": "Hn512"}
{"grid": "h512", "order": "nested"}
FESOM grids¶
These grids are designed for global ocean coverage, and are associated with the FESOM model. The grid format is case-insensitive, in the formats:
CORE2
CORE2_[CN]
DART
DART_[CN]
NG5
NG5_[CN]
where CORE2, DART and NG5 are distinct grids in increasing horizontal resolution, up to approximately 5 km. C and N define the point location respective to the supporting mesh elements, respectively in cell-centred and vertex point arrangements. The default arrangement is cell-centred or C.
Examples:
{"grid": "core2_n"}
{"grid": "NG5"}
ICON grids¶
ICON is a model used for both atmospheric and ocean modelling. ICON grids are identified by name (case-insensitive). Three sets of pre-defined grids are available:
MeteoSwiss (ICON-CH) — regional grids covering the Alpine region
Deutscher Wetterdienst (ICON-DWD) — global and regional grids for operational NWP
Max Planck Institute for Meteorology (ICON-MPIM) — global ocean-only grids for the ICON-O ocean model
MeteoSwiss (ICON-CH)¶
Regional operational grids covering the Alpine region. The version suffix -V1 is optional, version 1 the default. The grid names are case-insensitive:
ICON-CH1,ICON-CH1-V1, 1° resolutionICON-CH2,ICON-CH2-V1, 2° resolution
Deutscher Wetterdienst (ICON-DWD)¶
DWD grids follow the naming convention:
ICON-GRID-NNNN-RXXBYY-Z
where NNNN is a sequential grid number, rXXbYY is the refinement level (root division XX,
bisection level YY), and Z indicates the grid type (g global, n regional nest,
l limited area, r radiation auxiliary). Many grids are rotated 36° around the z-axis.
Global grids:
ICON-GRID-0002-R02B06-G, 40 kmICON-GRID-0004-R02B07-G, 20 kmICON-GRID-0006-R03B07-G, 13 kmICON-GRID-0008-R02B05-G, 80 kmICON-GRID-0010-R02B04-G, 160 kmICON-GRID-0012-R02B04-G, 160 kmICON-GRID-0014-R02B05-G, 80 kmICON-GRID-0016-R02B06-G, 40 kmICON-GRID-0018-R02B07-G, 20 kmICON-GRID-0020-R03B06-G, 26 kmICON-GRID-0022-R03B07-G, 13 kmICON-GRID-0024-R02B06-G, 40 kmICON-GRID-0026-R03B07-G, 13 kmICON-GRID-0030-R02B05-G, 80 kmICON-GRID-0033-R03B05-G, 53 kmICON-GRID-0036-R03B06-G, 26.5 kmICON-GRID-0039-R02B07-G, 20 kmICON-GRID-0054-R02B04-G, 160 km (idealized test grid)
Regional grids (Europe):
ICON-GRID-0027-R03B08-N02, 6.5 kmICON-GRID-0028-R02B07-N02, 20 kmICON-GRID-0031-R02B06-N02, 40 kmICON-GRID-0034-R03B06-N02, 26.5 kmICON-GRID-0037-R03B07-N02, 13 kmICON-GRID-0040-R02B08-N02, 10 kmICON-GRID-0048-R03B07-LR, 13 kmICON-GRID-0049-R03B08-L, 6.5 kmICON-GRID-0050-R02B07-N02, 20 km (Europe, North Atlantic and North Africa)ICON-GRID-0051-R03B07-N02, 13 km (Europe, North Atlantic and North Africa)ICON-GRID-0052-R03B07-LR, 13 kmICON-GRID-0053-R03B08-L, 6.5 km
Regional grids (Germany):
ICON-GRID-0041-R02B09-LR, 5 km (COSMO-DE)ICON-GRID-0042-R02B10-L, 2.5 km (COSMO-DE)ICON-GRID-0043-R19B06-LR, 4 km (COSMO-D2)ICON-GRID-0044-R19B07-L, 2 km (COSMO-D2)ICON-GRID-0045-R19B08-LN02, 1 km (COSMO-D2)ICON-GRID-0046-R19B06-LR, 4 km (enhanced COSMO-D2)ICON-GRID-0047-R19B07-L, 2 km (enhanced COSMO-D2)
Max Planck Institute for Meteorology (ICON-MPIM)¶
Global ocean-only grids for the ICON-O ocean model, rotated 37° around the z-axis and symmetrical about the equator. Each grid covers ocean areas only:
ICON-GRID-0036-R02B04-O, 160 kmICON-GRID-0020-R02B05-O, 80 kmICON-GRID-0046-R02B06-O, 40 kmICON-GRID-0024-R02B07-O, 20 kmICON-GRID-0016-R02B09-O, 5 kmICON-GRID-0040-R02B10-O, 2.5 kmICON-GRID-0038-R02B11-O, 1.2 km
Examples:
{"grid": "icon-ch2"}
{"grid": "ICON-CH1-V1"}
{"grid": "icon-grid-0022-r03b07-g"}
{"grid": "icon-grid-0044-r19b07-l"}
{"grid": "icon-grid-0024-r02b07-o"}
ORCA grids¶
These grids are designed for global ocean coverage, and are associated with the NEMO model. The grid format is case-insensitive, in the formats:
ORCAXXX
ORCAXXX_[FTUVW]
eORCAYYY
eORCAYYY_[FTUVW]
where the first letter stands for extended indicating coverage closer to the South pole. T, U, V or W define the point location respective to the supporting mesh elements, respectively in cell-centred, vertex and u/v edges point arrangements. The default arrangement is cell-centred or F.
Horizontal resolution numbers XXX and YYY are in increasing order 2 (XXX only), 1, 025, 12, approximately corresponding to resolution in degrees 2°, 1°, 0.25° and 1/12°.
Examples:
{"grid": "eORCA025_T"}
{"grid": "ORCA1"}