1. 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

2. 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)

3. 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/

4. 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

5. 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

6. 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

7. 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_<px>_<py>
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

8. Code Structure subdirectories in source/:
Basic/: data module, phys constants
Atham/: dynamical core
ProcessModules/: processes, forcing
=> add new process using process_data, .e.g. radiation
Configurations/: problem description
=> add new problem, e.g. coignimbrit eruption

9. Adding a Process Example: 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/volcano.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

10. Treating a New Problem Example: 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_diagnostic
register coignimbrit module in module configurations.F90 and Makefile.COMMON
use data from atham_module
add flag coignimbrit_setup in source/Basic/atham_module.F90
add coignimbrit calls in source/Atham/atham_setup.F90, atham_forcing.F90, atham_fallvelocity.F90, atham_output.F90

11. Questions, Comments?