########################
Initial condition inputs
########################

.. role:: bash(code)
   :language: bash

The INI_CONCS.0.nc file contains the initial concentration fields in molecules/cm3 on the model's grid at the beginning of the first hour. Among the species in INI_CONCS.0.nc, only those which are listed in the ACTIVE_SPECIES file of the :doc:`chemical scheme<chemistry>` plus the prescribed species are used. The concentration fields include the "normal" concentrations and the "conco" concentrations (for use in twostep) in case of a chained simulation i.e when the initial conditions are actually the end.nc file of a previous CHIMERE run. If the simulation is not to be chained, the "conco" are ignored. If no concentrations are provided for a given species, its initial field is set at 1d-17 (see :bash:`iniconc`). 

.. warning:: check that no species is set at null initial concentrations due to forgetting it in INI_CONCS.0.nc since no error is then raised.

The initial concentrations provided in dry air mole fractions can be converted into total air mole fractions for use by CHIMERE, following the specifications of the user in the ACTIVE_SPECIES file of the :doc:`chemical scheme<chemistry>`. 


See also :doc:`the fields plugins for CHIMERE </documentation/plugins/fields/chimere_icbc>` for documentation on this file and the information to provide to the CIF to generate it.

The format of INI_CONCS.0.nc is as follows, with NVERTI, NZONAL and NMERID given the relevant values, NS the number of species in the file (the "normal" and "conco" concentrations do not use the same name), UNITS is either ppb, in which case the values are converted into molec/cm3, or anything else, in which case it is assumed that they already are molec/cm3. XX PUT A CHECK OF THIS IN CHIMEREXX

.. literalinclude:: dump_iniconcs.txt
     :language: text

Important points:
  - there is only one record so that Time is not a record dimension.
  - the species names can be as long as SpStrLen = 23 characters including the _o
  - the concentrations must be written as :bash:`double` and NOT :bash:`float` to ensure enough precision for the adjoint.