The ATHAM Model: Code Structure and Usage

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The ATHAM Model Code Structure and Usage

• Michael Herzog, GFDL Princeton, USA
• Gunnar Luderer, MPI Mainz, Germany
• Joerg Trentmann, University of Mainz, Germany
• Christiane Textor, LSCE Paris, France
• ATHAM Workshop, Cambridge, UK, June 19-22, 2006

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Features of New ATHAM Code

• revised code structure
• namelist control to avoid recompile
• directory structure to separate code from i/o
• more user-friendly (makefiles, libraries, defined
  interfaces for adding new modules or variables)
• MPI support for parallel computing
• larger problem size (3d, more processes)(in
  cylindric coordinates serial only)

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Getting Started (unix-like system)

• expand archive file atham_dd.mm.yyyy_tar.gz
• subdirectories source/ and input/
• create directories exec/, output/, save/
• specify compiler/flags in source/Makefile.COMPILE
• compile code, create executable make atham,
  rebuild
• modify input files in input/
• run executable exec/atham (or with make run)
• visualize and analyze output files in output/

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Input Files

• vertical profiles
• INPUT_profile T(z), RH(z), u(z), v(z)
• INPUT_kinetic viscosity, free path length of air
  
• namelist files
• INPUT_atham_setup type, domain, timing
• INPUT_volcano processes, tracer, forcing
• INPUT_procsconfig, INPUT_fireforcing,
  INPUT_twomicrophys, INPUT_zgrid,
  INPUT_coignimbrit, INPUT_dynamic_setup

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INPUT_atham_setup

• type or configuration e.g. if volcano_setup
  read INPUT_volcano
• coordinate system cylindric or cartesian
• boundary condition cyclic or no slip
• output format netcdf or binary
• domain size, number of grid points
• number of processors for MPI version
• location of zoom, spatial resolution at zoom

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INPUT_volcano

• active process modules (bulk cloud microphysic)
• number of tracer (ntrac, ntgas, ntpas)
• tracer properties (cp, cv, density, radius)
• tracer names for output files

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Executing and Output

• executable exec/atham
• reads from input/ (except restart from output/)
• writes to output/ (old output files overwritten)
• output from Parallel (MPI) version
• separate restart and output files for each
  processor, e.g. ATDAT_ltpxgt_ltpygt
• output files can be recombined with exec/rebuild
• no(!) rebuild for ATDAT
• single output file if netcdf
• output can be viewed with grads (qview) or ferret

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Code Structure

• subdirectories in source/
• Basic/ data module, phys constants
• Atham/ dynamical core
• ProcessModules/ processes, forcing
• gt add new process using process_data, .e.g.
  radiation
• Configurations/ problem description
• gt add new problem, e.g. coignimbrit eruption

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Adding a ProcessExample Radiation for
volcano_setup

• add radiation.F90 in source/ProcessModules/
• use data from module process_data.F90 (and
  atham_module.F90)
• register radiation module in module
  processes.F90 and Makefile.COMPILE
• add temperature forcing to tetflx
• add radiation calls in source/Configurations/volca
  no.F90
• radiation_init in routine volcano_init
• radiation_preset in routine volcano_preset
• radiation_flux in routine volcano_flux
• diagnostics in volcano_diagnostic
  and volcano_final_diagnostic

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Treating a New ProblemExample Co-ignimbrite
Eruption

• add coignimbrit.F90 in source/Configurations/
  containing
• coignimbrit_init (coignimbrit_pointer)
• coginimbrit_preset
• coignimbrit_flux (incl. coignimbrit_forcing)
• coignimbrit_fallvel
• coignimbrit_diagnostic, coignimbrit_final_diagnost
  ic
• register coignimbrit module in module
  configurations.F90 and Makefile.COMMON
• use data from atham_module
• add flag coignimbrit_setup in source/Basic/atham_m
  odule.F90
• add coignimbrit calls in source/Atham/atham_setup.
  F90, atham_forcing.F90, atham_fallvelocity.F90,
  atham_output.F90

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Questions, Comments?