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This is done automatically provided both the Ndifferences between N-S and E-W boundary limits are both divisible by the corresponding increments without remainder. This represents a change in respect to EMOSLIB, which would adjust the area to fit. In the previous example, EMOSLIB would adjust the N/W/S/E boundaries to the more conventional area 90/0/-90/359.
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| Path | Keywords | MIR Behaviour | EMOSLIB Behaviour |
|---|---|---|---|
| Red | RESOL=AUTO, GRID=1.0/1.0 | Default Behaviour. Transformation from T1279 to an intermediate F90 full (regular) Gaussian grid (with an automatic truncation to T179) followed by a grid-to-grid interpolation from the F90 grid to 1.0/1.0. | Default Behaviour. Direct transformation from T1279 to 1.0/1.0, with an automatic truncation to T213 according to EMOSLIB's truncation table |
| Green | RESOL=AV, GRID=1.0/1.0 | Transformation from T1279 to the corresponding intermediate reduced octahedral Gaussian O1280, before going to 1.0/1.0. | Direct transformation from T1279 to 1.0/1.0, with no truncation. |
| Blue | RESOL=179, GRID=F90, and then GRID=1.0/1.0 | Transformation from T1279 to the F90 full (regular) Gaussian grid (with a user-specified truncation to T179) followed by a grid-to-grid interpolation from the F90 grid to 1.0/1.0. | Same as in MIR, but a separate MARS request is needed for each of the two steps. |
| Note |
|---|
Using the intermediate gausian grid can smooth the fields compared to EMOSLIB, which was going direct |
Usage of IFS spectral transform library
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MIR does not support the 12-point interpolation method, used by EMOSLIB for rotated grids. Therefore, the default interpolation method used is the linear. Rotated spherical harmonics are not supported in MIR or EMOSLIB.
Known Issues
- Problems with winds on rotated grids. WS is correct, direction is wrong
- performance for small subareas