3.1. The input files

The use of the externalized surface software in off-line mode requires the preparation of several types of file, especially the input data necessary for the run and the definition of the options specified in the namelist .

• OPTIONS.nam is the namelist name used in the off-line model. The same namelist is used for the PGD, PREP and RUN facilities. The description of the different namelist blocks for PGD ("The physiographic fields") and PREP ("Initialization of the prognostic fields") tools are described in the next chapter. The namelist block where functionnalities of the off-line run in terms of Input/Output is named NAM_IO_OFFLINE
• the princip of an off-line simulation is that the atmospheric variables are known in advance. Thus, time series of air temperature, humidity, wind speed, precipitation, pressure and radiation terms are known. These data are pre-treated in order to be written in specific files (see below) called forcing files.
• like for any model, some parameters related to the scheme have to be set and state variable have to be initialized. These two tasks are performed by mean of tools PGD and PREP which lead to create the initial file used in the simulation