PREP_NEST_PGD

In order to run models with the gridnesting technique, a condition on the orography must be satisfied. In the following, if file 2 is completely included in (and therefore in interaction during the run with) file 1, file 2 will be called the SON file, and file 1 the DAD file. In the following, the DAD file number must be smaller than any of its SON number. The condition on the orography is: “the mean of orography for a SON file in the domain corresponding to the grid mesh of its DAD file, must be equal to the orography of the DAD file in this mesh”. Such a condition is not automatically satisfied when using enhanced orographies. The program PREP_NEST_PGD performs post-treatments on the orographies of up to 8 PGD files that will be used to create initialization files for a gridnested run. It modifies the orography of a DAD from the mean of the orography of its (several) SON(s).

PREP_NEST_PGD program and its corresponding namelist and function

Executable

Namelist

Function

PREP_NEST_PGD

PRE_NEST_PGD1.nam

Prepare surface file when grid nesting is used

The following namelists can be used in the PRE_NEST_PGD1.nam file :

NAM_CONFIO

NAM_CONFIO content

Fortran name

Fortran type

Default value

CIO_DIR

CHARACTER(LEN=512)

LVERB_OUTLST

LOGICAL

.TRUE.

LVERB_STDOUT

LOGICAL

.FALSE.

LVERB_ALLPRC

LOGICAL

.FALSE.

NGEN_VERB

INTEGER

4

NGEN_ABORT_LEVEL

INTEGER

2

NBUD_VERB

INTEGER

4

NBUD_ABORT_LEVEL

INTEGER

2

NIO_VERB

INTEGER

4

NIO_ABORT_LEVEL

INTEGER

2

LIO_COMPRESS

LOGICAL

.TRUE.

CIO_COMPRESS_ALGO

CHARACTER(LEN=10)

‘ZSTD’

NIO_COMPRESS_LEVEL

INTEGER

4

LDIAG_REDUCE_FLOAT_PRECISION

LOGICAL

.FALSE.

LIO_ALLOW_REDUCED_PRECISION_BACKUP

LOGICAL

.FALSE.

LIO_ALLOW_NO_BACKUP

LOGICAL

.FALSE.

LIO_NO_WRITE

LOGICAL

.FALSE.

NFILE_NUM_MAX

INTEGER

999

Warning

  • If a file is not found in the netCDF fileformat, Meso-NH will check if it exists in the LFI format and use it if found. This could be useful if you need to mix the reading of different files with different fileformats.

  • CIO_DIR : directory used to write outputs, backups and diachronic files (current directory by default). It can be overridden by CBAK_DIR for backups and diachronic files and by COUT_DIR for outputs.

  • LVERB_OUTLST : flag to write application messages in OUTPUT_LISTINGn files (in current directory, n is for the current model)

  • LVERB_STDOUT : flag to write application messages on the standard output

  • NGEN_VERB : set the verbosity level for generic messages

    • 0 : no messages

    • 1 : fatal messages

    • 2 : error messages (and lower values)

    • 3 : warning messages (and lower values)

    • 4 : info messages (and lower values)

    • 5 : debug messages (and lower values)

  • NGEN_ABORT_LEVEL : set the minimum level of generic message to abort the application (same levels as for NGEN_VERB)

  • NBUD_VERB : set the verbosity level for budget messages (same levels as for NGEN_VERB)

  • NBUD_ABORT_LEVEL : set the minimum level of budget message to abort the application (same levels as for NGEN_VERB)

  • NIO_VERB : set the verbosity level for IO messages (same levels as for NGEN_VERB)

  • NIO_ABORT_LEVEL : set the minimum level of IO message to abort the application (same levels as for NGEN_VERB)

Warning

Not all messages use this infrastructure. Therefore, some of them are not affected by these options.

  • LIO_COMPRESS : enable lossless compression of data for all files. This can have a negative impact on performance. This option takes precedence over their equivalent NAM_BACKUP and NAM_OUTPUT namelists.

  • CIO_COMPRESS_ALGO: set the compression algorithm (only for files in netCDF format, not for LFI format). The allowed values are ‘ZSTD’ (for Zstandard compression,default value), ‘DEFLATE’ (for zlib compression) or ‘NONE’. This option takes precedence over their equivalent in NAM_BACKUP and NAM_OUTPUT namelists (only if LIO_COMPRESS=.TRUE. which is the default). If set to ‘NONE’, all compression will be disabled (that stands also for lossy compression).

  • LOUT_COMPRESS_LEVEL : set the compression level. The value must be in the 0 to 9 interval (0 for no compression, 9 for maximum compression). This option takes precedence over their equivalent in NAM_BACKUP and NAM_OUTPUT namelists (only if LIO_COMPRESS=.TRUE. which is the default).

  • LDIAG_REDUCE_FLOAT_PRECISION : force writing of floating points numbers in single precision for diagnostic files (written by the DIAG program)

  • LIO_ALLOW_REDUCED_PRECISION_BACKUP : flag to allow writing of backup files with a reduced precision as well as reading of reduced precision files and files written with Meso-NH compiled with a lower precision for integers or reals (ie MNH_INT=4 and MNH_REAL=4).

  • LIO_ALLOW_NO_BACKUP : allow to have no valid backup time (useful for some tests)

  • LIO_NO_WRITE : disable file writes (useful for benchs)

  • NFILE_NUM_MAX : maximum number for numbered files (mainly backup and output files). If less than 1000, the numbers will be on 3 digits. From 1000, they will be on the number of digits of NFILE_NUM_MAX (5 if NFILE_NUM_MAX=12345).

NAM_PGDN

Warning

This namelist comes from SURFEX 9.0.0 user guide https://www.umr-cnrm.fr/surfex/IMG/pdf/surfex_tecdoc.pdf.

NAM_PGDN content

Fortran name

Fortran type

Default value

YPGDN

CHARACTER(LEN=128)

IDAD

INTEGER

0

  • YPGDN : name of the PGD file N.

  • IDAD : number of the DAD file of file N. The DAD file number IDAD must be smaller than N.

Note

N goes from 1 to 8, by example :

&NAM_PGD1 YPGD1='PGDFILE1' /
&NAM_PGD2 YPGD2='PGDFILE2', IDAD=1 /

NAM_NEST_PGD

NAM_NEST_PGD content

Fortran name

Fortran type

Default value

YNEST

CHARACTER(LEN=2)

  • YNEST : string of 2 characters to be added to the PGD file names to define the corresponding output PGD file names. The input file YPGDN (NAM_PGDN) will be modified into file YPGD.nestYNEST.

NAM_CONF_NEST

NAM_CONF_NEST content

Fortran name

Fortran type

Default value

NHALO_MNH

INTEGER

1

JPHEXT

INTEGER

1

  • NHALO_MNH : Size of the halo for parallel distribution. This variable is related to computer performance but has no impact on simulation results. NHALO_MNH must be equal to 3 for WENO5 cases in parallel runs.

  • JPHEXT : Horizontal External points number. JPHEXT must be equal to 3 for cyclic cases with WENO5.