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Introduction

This presentation: a few explanations, many pointers to web sites and to paths on French super-computers. A large part of this presentation is a bird's eye inventory of input files for LMDZ.

A lot of this, you do not have to know if you use libIGCM, because choosing and getting the necessary files will be automated. Note: there are regular training sessions for libIGCM. The information here may be useful if you have non-standard needs.

LMDZ may be coupled with other models:

The sets of input files and input parameters vary with the set of models you couple. For example, you need to provide sea-surface temperature in an input file only if you do not couple LMDZ with an ocean model.

LMDZ itself has several configurations which impact the input files it requires:

  • Longitude-latitude "dynamical" part of the model or Dynamico
  • 1 or 3 dimensions
  • Nudging or not
  • Realistic or idealized "physical" part of the model

For example, you need to provide special input files for nudging.

In the rest of this presentation, we will look only at a particular setup, which is a good reference point to understand input:

  • LMDZ alone (no coupling with another model), longitude-latitude dynamics
  • 3 dimensions
  • No nudging
  • Realistic (terrestrial) physics and surface (well, more or less: the continents and relief are there, but not Orchidee)

We may distinguish several types of input, conceptually:

  • Initial state
  • Boundary conditions: surface conditions and solar irradiance
  • Forcing inside the atmosphere: concentration of greenhouse gases, ozone field, fields of aerosols
  • Number and behaviour of tracers
  • Behaviour of the gcm: choosing between alternate physical parameterizations, choosing parameters within physical parameterizations, dynamics parameters, etc.
  • Choice of output

From a practical computer-side point of view, we will have to provide several types of input files:

  • NetCDF files
  • Text files
    • files in a special format for a procedure called getin
    • a file in a special format to describe tracers
    • XML files