VERSION 3 REGRID PROGRAM (release 3-7)
(Updated December 23, 2004)

This is the main directory of the REGRID program in the MM5 modeling 
system Version 3. Everything a user needs to run the REGRID program 
is contained in this directory.

For questions, please send emails to mesouser@ucar.edu

For detailed documentation about REGRID program, please see
pregrid/Doc, and regridder/Doc directory.

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What is in V3 REGRID?

V3 REGRID is replacing V2 Datagrid program, is structured similarly to
V2 REGRID. For initial information on REGRID development, please see

http://www2.mmm.ucar.edu/mm5/mm5v2/regrid.html

V3 REGRID program uses V3 data format, which is different from
that in V2. For details on V3 data format, please see

http://www2.mmm.ucar.edu/mm5/mm5v3.html

REGRID is a Fortran 90 program, and requires Fortran 90 compiler.

REGRID is supported for Cray, Alpha, HP, IBM, SGI, SUN, and Fujitsu with
their native compilers, and PC running Linux using Portland Group Fortran
90 compiler. If your machine isn't one of the ones supported or the
compiler isn't the native one from the vendor, you need to edit the Makefile.

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***************************************************************
Also see the online self-tutorial at
http://www2.mmm.ucar.edu/mm5/mm5v3/tutorial/teachyourself.html
***************************************************************

To compile for both pregrid and regridder:

- Type 'make' in the REGRID directory to compile.

- When make is successful, executables will be created in appropriate
  subdirectories.

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To run pregrid:

If you have a dataset that is supported by pregrid, cd to pregrid
directory, edit pregrid.csh to execute the program.

To obtain dataset requested by pregrid, see pregrid/Doc for details.

If you have a dataset that is NOT supported by pregrid, read the
documentation in pregrid/Doc/Format carefully, prepare your own program
and put your data in the format described in the document.

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To run regridder:

Once you have data written in the intermediate format, whether it is
done by pregrid program, or your own program, cd to regridder directory,
edit namelist.input, and type regridder to execute the program.

Required input data for regridder include TERRAIN_DOMAIN1 generated from
running TERRAIN program, and output from pregrid.

The output file from regridder is REGRID_DOAMIN1.

If you need to run regridder for multiple domains, edit namelist to
set appropriate input TERRAIN output files. regridder will produce
output files accordingly, i.e. TERRAIN_DOMAIN2 --> REGRID_DOAMIN2, etc.

For information how to use the namelist, please read Doc/README.namelist.

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Note on minimum data requirement:

There is a minimum amount of data required to run the MM5 model. These
are U and V component of wind, temperature, relative humidity and height at 
mandatory levels: 100, 150, 200, 250, 300, 400, 500, 700, 850, 1000 mb, 
and at surface. Sea-level pressure (SLP) and SST are also mandatory. 
Without SLP and SST, regridder will stop. Without first guess fields 
for U, V, T, RH at surface, regridder will currently use 1000 mb data 
to fill surface fields. Please note that this is not a realistic 
representation of surface condition when there is significant topography
in the model domain. 
If regridder does not find surface data, it will print out a warning
message at each processing time.  One can use namelist option in INTERPF: 
usesfc = .FALSE. to exclude the use of improperly generated surface data.
Still, providing surface data is a preferred choice.

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Note on data required to run land-surface model (LSM) option in MM5:

The LSM option in MM5 requires additional data than what are normally
required to run MM5 (for example, 3-dimensional pressure level and surface
analyses of wind, temperature, relative humidity, etc.). 
See 'Land-Surface Model' section of 'Version 3 MM5 Modeling System at a Glance'
on the Web for a list of required data for LSM:

http://www2.mmm.ucar.edu/mm5/mm5v3/v3-intro.html

These additional data unfortunately are not available in every dataset.  
Currently the datasets that provide these data are: NCEP/NCAR Reanalysis (NNRP),
and Eta212 grid real-time data provided on NCEP ftp server.

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Files/directories in this directory:

CHANGES:   description of changes since early releases
Makefile:  makefile for both pregrid and regridder
README:    general information about how to run REGRID
configure.rules: make rules (do not require change)
pregrid:   directory of pregrid programs
regridder: directory of regridder program
ibm-regrid.deck:  batch job deck for NCAR's IBM
cray-regrid.deck: batch job deck for NCAR's Cray 
           (may be modified for other Cray environment)