.. _spawning:

SPAWNING
***************************************************************************** 

The :program:`SPAWNING` program performs horizontal interpolation from one Meso-NH file (file 1) to another (file 2). The grid of file 2 must be entirely contained within the grid of file 1. While file 2 can be used directly for a model run, its surface fields especially orography are smoothed. However, the model can still be run with both files using grid nesting, as an iterative procedure ensures the nesting condition for orography is met. The domain of file 2 can be defined in two ways:

* By specifying the parameters in the namelist :ref:`nam_grid2_spa`.

* By using the domain of another Meso-NH file with a grid that is coherent with the input file. For example, this could be a PGD file generated by :ref:`prep_pgd`, where the domain is derived from file 1 and uses the same specifications as those in :ref:`nam_grid2_spa`.

.. warning::

   * When you want to force Meso-NH by Meso-NH you cannot create an independent grid at that time, the horizontal grids must be consistent.

   * Vertical grid can be changed when you force Meso-NH by an other Meso-NH simulation, without grid nesting.

.. csv-table:: SPAWNING program and its corresponding namelist and function
   :header: "Executable", "Namelist", "Function"
   :widths: 30, 30, 30

   "SPAWNING", "SPAWN1.nam", "Horizontal interpolations from a Meso-NH file into another Meso-NH file, with a finer resolution and smaller domain."

The following namelists can be used in the :file:`SPAWN1.nam` file :

* :ref:`nam_blankn`
* :ref:`nam_grid2_spa`
* :ref:`nam_lunit2_spa`
* :ref:`nam_spawn_surf`  
 
.. include:: namelists/nam_blankn.rst
.. include:: namelists/nam_grid2_spa.rst
.. include:: namelists/nam_lunit2_spa.rst
.. include:: namelists/nam_spawn_surf.rst