Model tasks

In FALL3D, the former pre-process auxiliary programs (SetTgsd, SetDbs and SetSrc) have been parallelized and embedded within the main code, so that a single executable file exists for all the pre-process steps and execution workflow. These formerly independent programs can still be run individually invoked as model tasks (specified by a program call argument) or, alternatively, concatenated as a single model execution. In the first case, pre-process tasks generate output files that are later on furnished as inputs to the model (or to subsequent pre-process tasks). In contrast, the second option does not require of intermediate file writing/reading and, therefore, saves disk space and overall computing time.

The next figure shows a diagram of the FALL3D workflow, the data transfer between different tasks and the involved I/O files:

FAILED workflow

List of model tasks

This is the list of available tasks:

  • Task SetTgsd generates particle Total Grain Size Distributions (TGSD) for species of category particles or radionuclides
  • Task SetDbs interpolates (for a defined time slab) meteorological variables from the meteorological model grid to the FAL3D computational domain
  • Task SetSrc generates emission source terms for the different species. It can also perform a-priori particle aggregation and a TGSD cut-off
  • Task FALL3D runs the FALL3D solver
  • Task ALL runs all previous tasks concatenated
  • Task PosEns merges and post-processes outputs from single ensemble members. Only for ensemble runs
  • Task PosVal validates single or ensemble-based results

All the tasks require a common configuration file as an input, i.e. the namelist file name.inp. In addition, there are different input and output files associated with each task, as is summarized in the next table:

TaskNamelist file requiredMandatory
input files
Optional input filesOutput files
SetTgsdYesCustom distributionname.specie.tgsd
SetDbsYesMeteorological file in netCDF formatDictionary,
SetSrcYesname.specie.tgsd, name.dbs.proname.specie.grn, name.src
FALL3DYesname.src, name.specie.grn,,
AllYesMeteorological file in netCDF,
PosEnsYesList of or name.ens.ncsee section Task PosVal

The task SetEns is not explicitly executed by the user, but is automatically invoked when ensemble runs are performed in order to set up the ensemble. The ensemble run option is enabled whenever FALL3D is executed with the argument -nens, which allows one to define the size of the ensemble.


  • The model tasks SetEns, PosEns and PosVal have been added from version 8.1.

The namelist file

The namelist file name.inp is an input configuration file in ASCII format required by all tasks. It consists of a set of blocks defining physical parameterisations, time ranges, model domain, emission source, numerical schemes, etc. Each task reads only the necessary blocks generating self-consistent input files. Parameters within a block are listed one per record, in arbitrary order, and optionally can be followed by one (or more) blank space and a comment. Comments start with the exclamation mark symbol "!". Real numbers can be expressed using the FORTRAN notation (e.g. 12E7).

See section Namelist file for a full description of the file structure.

The LOG file

In addition, each task TASK produces a log file name.TASK.log reporting relevant information and potential errors or warnings.