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Subsections

3.1 Scientific options

3.1.1 Spectral fit on dynamic fields

If you wish to post-process surface dynamic fields or upper air dynamic fields on pressure levels, potential temperature levels or potential vorticity levels, it is possible to perform a spectral fit between the vertical interpolations and the horizontal interpolations. The spectral fit will remove the nemerical noise which has been generated by the vertical interpolation and which is beyond the model truncation.

LFITP

:

Definition: : Spectral fit of post-processed fields on pressure levels.
Scope: : Boolean.
Default value: : .TRUE.
Namelist location: : NAMFPC

LFITT

:

Definition: : Spectral fit of post-processed fields on potential temperature levels.
Scope: : Boolean.
Default value: : .FALSE.
Namelist location: : NAMFPC

LFITV

:

Definition: : Spectral fit of post-processed fields on potential vorticity levels.
Scope: : Boolean.
Default value: : .FALSE.
Namelist location: : NAMFPC

LFIT2D

:

Definition: : Spectral fit of 2D post-processed fields.
Scope: : Boolean.
Default value: : .TRUE.
Namelist location: : NAMFPC

Notice :

If you wish to post-process upper air dynamic fields on height levels or hybrid levels, it is not possible to apply such spectral fit because the horizontal interpolations are performed before the vertical interpolation in order to respect the displacement of the planetary boundary layer.
If you post-process dynamic fields which are not represented by spectral coefficients in the model, then these fields will not be spectrally fitted, even if the corresponding key LFITxx is .TRUE. In the same way, if you post-process a specific dynamic field which is represented by spectral coefficients in the model, then this field will be spectrally fitted whenever the corresponding key LFITxx is .TRUE.. However it is possible to change the native representation of a field : refer to section 3.3.1.

3.1.2 Tuning of the spectral filters

Several fields can be smoothed via tunable filters activated in spectral space (refer to appendix A.4 for the formulation of these filters). These parameters are contained in the specific namelist NAMFPF.

LFPBED, RFPBED

:

Definition: : Respectively switch and intensity of the filter on the so-called "derivative" fields, that is : horizontal derivatives or those which are build after horizontal derivatives (absolute and relative vorticites, divergence, vertical velocity, stretching and shearing deformations, potential vorticity and all fields interpolated on potential vorticity levels).
Scope: : Respectively boolean and real. Unit : adimensional
Default value: : LFPBED=.TRUE. ; RFPBED $\approx$ 3.08^3.1 in ARPEGE/IFS, RFPBED=6. in ALADIN.

NFMAX

:

Definition: : Truncation threshold of each (sub-)domain for the filter on the so-called "derivative" fields (used only in ARPEGE/IFS if the model is stretched).
Scope: : Integer array. Maximum size : 15 items.
Default value: : If CFPFMT='GAUSS' then NFMAX(1)=NFPMAX(1)*FPSTRET.
Else if CFPFMT='MODEL' then NFMAX(1)=NFPMAX(1)*FPSTRET which means that the fields will never be filtered.
Else NFPMAX is computed like for a quadratic grid :
so that 3*NFMAX(:)+1 $\ge$ min(NLAT(:),NLON(:))

LFPBEG, RFPBEG

:

Definition: : Respectively switch and intensity of the filter on geopotential.
Scope: : Respectively boolean and real. Unit : adimensional
Default value: : LFPBEG=.TRUE. ; RFPBEG=4. in ARPEGE/IFS, RFPBEG=6. in ALADIN.

LFPBET, RFPBET

:

Definition: : Respectively switch and intensity of the filter on temperature.
Scope: : Respectively boolean and real. Unit : adimensional
Default value: : LFPBET=.TRUE. ; RFPBET=4. in ARPEGE/IFS, RFPBET=6. in ALADIN.

LFPBEP, RFPBEP

:

Definition: : Respectively switch and intensity of the filter on medium sea level pressure.
Scope: : Respectively boolean and real. Unit : adimensional
Default value: : LFPBEP=.TRUE. ; RFPBEP=4. in ARPEGE/IFS, RFPBEP=6. in ALADIN.

LFPBEH, RFPBEH

:

Definition: : Respectively switch and intensity of the filter on relative humidity.
Scope: : Respectively boolean and real. Unit : adimensional
Default value: : LFPBEH=.TRUE. ; RFPBEH=4. in ARPEGE/IFS, RFPBEH=6. in ALADIN.

Notice :

Only one filter can be appled to a given field ; consequently, in case of ambiguity in the choice of filter (example : geopotential on an iso-PV surface), only the "derivative" filter is applied.
Filters are applied even if the post-processed fields should be represented in spectral coefficients.

3.1.3 Climatology

In horizontal interpolations the usage of auxilary climatology data improves the accuracy of the upper air fields when interpolated on surface-dependent levels, and of several surface fields. Appendix A.3 explains how to make such files.

NFPCLI

:

Definition

: Usage level for climatology data :

if NFPCLI=0 climatology data are not used.
if NFPCLI=1 the horizontal interpolations use the surface geopotential and the land-sea mask of a target climatology file. In this case the climatology file name in the local script should be : "const.clim.CFPDOM(i)" where i is the (sub-)domain subscript.
if NFPCLI=3 the horizontal interpolations use a larger set of climatology surface fields, including constant and monthly values. In this case two climatology files are used : one with the source geometry and one with the target geometry. In the local script the source climatology file name should be : "Const.Clim while the target climatology file name should be : "const.clim.CFPDOM(i)" where i is the (sub-)domain subscript.

The table 3.1 lists the climatology fields read in function of the namelist keys.

Scope

: Integer which value can be only 0, 1 or 3.

Default value

: NFPCLI=0

Namelist location

: NAMFPC

**Table 3.1:** Climatology fields read in function of the namelist keys.
Field	Namelist keys
surface geopotential	`NFPCLI` $\ge$ 1
land-sea mask	`NFPCLI` $\ge$ 1 and (`LMPHYS` or `LEPHYS`)
surface temperature	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
relative surface wetness	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
deep soil temperature	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
relative deep soil wetness	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
snow depth	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
albedo	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
emissivity	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
standard deviation of surface geopotential	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
percentage of vegetation	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
roughness lenth	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
anisotropy coefficient of topography	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
direction of the main axis of topography	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
type of vegetation	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
minimum stomatal resistance	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
percentage of clay	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
percentage of sand	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
root depth	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
leaf area density	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
thermal roughness length	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`)
surface snow albedo	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`) and `LVGSN`
surface snow density	`NFPCLI` $\ge$ 3 and (`LMPHYS` or `LEPHYS`) and `LVGSN`

RFPCORR

:

Definition: : critical difference of surface geopotential between the model and the source climatology in order to correct surface temperature through the standard vertical profile.
Scope: : Real. Unit : J/kg
Default value: : 300.*g
Namelist location: : NAMFPC

RFPCSAB

:

Definition: : Critical difference of sand percentage between the model and the source climatology in order to compute the relative soil moisture.
Scope: : Real. Unit : adimensional.
Default value: : 0.01
Namelist location: : NAMFPC

RFPCD2

:

Definition: : Critical difference of depth between the model and the source climatology in order to compute the relative soil moisture.
Scope: : Real. Unit : m.
Default value: : 0.001 m.
Namelist location: : NAMFPC

LFPMOIS

:

Definition

: Month selected while using climatology data (used only if NFPCLI ge 3) :

if LFPMOIS= .FALSE. then the month is the one of the model (forecast).
if LFPMOIS=.TRUE. then the month is the one of the input initial file. This option should lead to less accurate fields but it enables in-line post-processing^3.2.

Scope

: Boolean.

Default value

: .FALSE.

Namelist location

: NAMFPC

3.1.4 Optional pronostic fields

The model is able to run with optional pronostic fields. These fields would be interpolated by the post-processing if they are declared as present in the model. But if they are not, then the post-processing would create and fullfill them as it can.

NFPASS

:

Definition: : Number of spectral passive scalars in the model.
Scope: : Integer between 0 and 5
Default value: : 0
Namelist location: : NAMDIM

LNHDYN

:

Definition: : Control of the non-hydrostatic model ; if LNHDYN=.TRUE. then pressure departure and vertical divergence fields are read in and thus interpolated. Else pressure departure and vertical divergence are created. Pressure departure field is then fullfilled with zero, while vertical divergence is diagnosed.
Scope: : Boolean. To run the model with this option you need the ALADIN software.
Default value: : .FALSE.
Namelist location: : NAMCT0

LSPQ, LGPQ

:

Definition: : Respectively spectral and gridpoint atmospheric specific humidity represented as pronostic variable in the model.
Scope: : Boolean. Possible values : any pair of booleans except (.TRUE.,.TRUE.)
Default value: : if LECMWF=.TRUE. then (LSPQ,LGPQ)=(.FALSE.,.TRUE.).
Else (LSPQ,LGPQ)=(.TRUE.,.FALSE.).
Namelist location: : NAMDIM

LSPL, LGPL

:

Definition: : Respectively spectral and gridpoint atmospheric liquid water represented as pronostic variable in the model.
Scope: : Boolean. Possible values : any pair of booleans except (.TRUE.,.TRUE.)
Default value: : if LECMWF=.TRUE. then (LSPL,LGPL)=(.FALSE.,.TRUE.).
Else (LSPL,LGPL)=(.FALSE.,.FALSE.).
Namelist location: : NAMDIM

LSPI, LGPI

:

Definition: : Respectively spectral and gridpoint atmospheric solid water (ice) represented as pronostic variable in the model.
Scope: : Boolean. Possible values : any pair of booleans except (.TRUE.,.TRUE.)
Default value: : if LECMWF=.TRUE. then (LSPI,LGPI)=(.FALSE.,.TRUE.).
Else (LSPI,LGPI)=(.FALSE.,.FALSE.).
Namelist location: : NAMDIM

LSPA, LGPA

:

Definition: : Respectively spectral and gridpoint cloud fraction represented as pronostic variable in the model.
Scope: : Boolean. Possible values : any pair of booleans except (.TRUE.,.TRUE.)
Default value: : if LECMWF=.TRUE. then (LSPA,LGPA)=(.FALSE.,.TRUE.).
Else (LSPA,LGPA)=(.FALSE.,.FALSE.).
Namelist location: : NAMDIM

LSPO3, LGPO3

:

Definition: : Respectively spectral and gridpoint ozone mixing ratio represented as pronostic variable in the model.
Scope: : Boolean. Possible values : any pair of booleans except (.TRUE.,.TRUE.)
Default value: : (.FALSE.,.FALSE.).
Namelist location: : NAMDIM

3.1.5 Adiabatic post-processing

To run the post-processing in the adiabatic model, you should carefully remove the physical fields from the model, by setting the following variables in namelists :

/NAMPHY 
   LSOLV=.FALSE.,
   LFGEL=.FALSE.,
   LFGELS=.FALSE.,
   LMPHYS=.FALSE.,
   LNEBN=.FALSE.,
/END
/NAMDPHY  
   NVSO=0,
   NVCLIV=0,
   NVRS=0,
   NVSF=0,
   NVSG=0,
   NCSV=0,
   NVCLIN=0,
   NVCLIP=0,
/END

3.1.6 Horizontal interpolations

It is possible to control the kind of horizontal interpolations, for dynamic fields on one side, and for physical fields and fluxes on the other side :

NFPINDYN

:

Definition

: control of horizontal interpolations for dynamic fields :

NFPINDYN=12 : quadratic interpolations
NFPINDYN=4 : bilinear interpolations
NFPINDYN=0 : to adopt the nearest point rather than interpolating.

Scope

: Integer which value can be only 0, 4 or 12.

Default value

: 12

Namelist location

: NAMFPC

NFPINPHY

:

Definition

: control of horizontal interpolations for physical fields and fluxes :

NFPINPHY=12 : quadratic interpolations
NFPINPHY=4 : bilinear interpolations
NFPINPHY=0 : to adopt the nearest point rather than interpolating.

Scope

: Integer which value can be only 0, 4 or 12.

Default value

: 12

Namelist location

: NAMFPC

Notice: setting NFPINPHY=NFPINDYN=0 enables to run the post-processing without any climatology, even when any ISBA field is requested.

3.1.7 The problem of lakes and islands

When the output resolution is so that a single gridpoint lake or island is created, the horizontal interpolations taking into account the land/sea nature will not work properly since no neighbouring points will be of the same nature as the target point ; hence all the neighbouring points will be used in the interpolation process. This can lead to irrealistic temperatures or water contents.
To avoid this, an alternative option has been developped :

LFPLAKE

:

Definition

: Special treatment for lake and islands ; when it is set to .TRUE. the surface and deep soil temperatures and water contents will be modified as follows :

values on isolated lakes or islands gridpoint created by the interpolations will be overwritten by the climatology data
values on any lake gridpoint, as identified by the climatology, will be overwritten by the climatology data (to improve the existing quality of the climatology data over lakes, when it is possible)

Scope

: Boolean.

Default value

: .FALSE.

Namelist location

: NAMFPC

Notice: the positive impact of the feature still need be proved.

3.1.8 Computation of CAPE

The computation of the Convective Available Potential Energy (CAPE) is widely tunable :

NFPCAPE

:

Definition

: Kind of computation :

NFPCAPE=1 : computation starts from the lowest model level
NFPCAPE=2 : computation starts from the most unstable model level
NFPCAPE=3 : computation starts from the recomputed temperature and relative moisture at 2 meters
NFPCAPE=4 : computation starts from the analysed temperature and relative moisture at 2 meters

Scope

: Integer which value can be only 1,2 3 or 4.

Default value

: 2

Namelist location

: NAMFPC

NCAPEITER

:

Definition: : Number of iterations in the Newton's loops.
Scope: : Integer.
Default value: : 2
Namelist location: : NAMCAPE

NETAPES

:

Definition: : Number of intermediate layers used for calculation of vertical ascent between two model pressure levels.
Scope: : Integer.
Default value: : 2
Namelist location: : NAMCAPE

GCAPEPSD

:

Definition: : Depth of layer above the ground in which most unstable parcel is searched for (used with NFPCAPE=2 only).
Scope: : Real. Unit : Pascal.
Default value: : 30000 Pa.
Namelist location: : NAMCAPE

GCAPERET

:

Definition: : Fraction of the condensate which is retained (ie : which does not precipitate).
Scope: : real value between 0. and 1.
Default value: : GCAPERET=0. ("irreversible" or pseudo-adiabatic moist ascent : clouds condensates precipitate instantaneously and thus does not affect the buoyancy).
Namelist location: : NAMCAPE

3.1.9 Miscellaneous

LFPQ

:

Definition: : To control the interpolation of relative versus specific humidity on height or eta levels. Relative humidity is considered to have better conservative properties through interpolations than mixing ratio, even if it is not a conservative quantity. If LFPQ=.FALSE. the relative humidity is interpolated then the specific humidity is deducted. If LFPQ=.TRUE. the specific humidity is interpolated then the relative humidity is deducted.
Scope: : Boolean.
Default value: : .FALSE. (this is the recommended value).
Namelist location: : NAMFPC

RFPVCAP

:

Definition: : Minimum pressure of model level to provide an equatorial cap for fields computed on potential vorticity levels.
Scope: : Real. Unit : Pascal.
Default value: : if LECMWF=.TRUE. then RFPVCAP=8900. Pa ; else RFPVCAP=15000. Pa
Namelist location: : NAMFPC

NDLNPR

:

Definition: : Discretization of $\delta\left(\ln p\right)$ . Set NDLNPR=1 to adopt the proper discretization to conform the non-hydrostatic model or whenever you post-process on "non-hydrostatic" field (pressure departure, vertical divergence or true vertical velocity). orticity levels.
Scope: : Integer which value can be only 0 or 1.
Default value: : 1
Namelist location: : NAMDYN

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2002-10-17