Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

Default truncation values for "RESOL=AUTO" (Automatic Truncation) have also changed. MIR uses a formula to truncate the spectral series to correspond to the equivalent linear Gaussian grid, replacing the fixed table used in EMOSLIB. Transformations to regular latitude-longitude grids then use an intermediate full (regular) Gaussian grid.

...

PathKeywordsNew keywordsMIR BehaviourEMOSLIB Behaviour
Red

RESOL=AUTO,

GRID=1.0/1.0

TRUNCATION=AUTO,

INTGRID=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

TRUNCATION=NONE,

INTGRID=O1280,

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

TRUNCATION=179,

INTGRID=F90,

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.


Anchor
emoslib
emoslib

emoslib
Expand
titleLegacy EMOSLIB behaviour >
Anchor
emoslib

With EMOSLIB spectral fields are by default automatically truncated before interpolation to grid fields to reduce data volumes and spurious aliased values. When automatic truncation is applied MARS issues a warning message like INTFB: Resolution automatically set to ....

The truncation can be controlled using the keywords truncation and intgrid. Users wanting to post-process at the full archived resolution can specify truncation = none in the request.

Legacy EMOSLIB default spectral truncation wave number for given lat/lon grid increment ∆.
Grid increment [deg]Truncation
2.5 ≤ ∆     T63
1.5 ≤ ∆ < 2.5T106
0.6 ≤ ∆ < 1.5T213
0.4 ≤ ∆ < 0.6T319
0.3 ≤ ∆ < 0.4T511
0.15 ≤ ∆ < 0.3 T799
0.09 ≤ ∆ < 0.15T1279
0.0  ≤ ∆ < 0.09T2047


...