Testsuite: art_global_r02b05_OH_CHEMISTRY
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This script prepares an ICON-ART global NWP experiment using simplified tropospheric OH chemistry. The configuration is based on a global domain at ~80 km resolution (R02B05). A simplified chemical mechanism is used to represent OH-related oxidation processes.

Required data for this testcase:
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  - icon_grid_0007_R02B04_R.nc                (radiation grid for R02B04)
  - icon_grid_0008_R02B05_G.nc                (dynamics grid for R02B05)
  - icon_extpar_0008_R02B05_G.nc              (external parameters for R02B05)
  - ifs_remap_0008_R02B05_2013110500.nc       (IFS input for initialization)
  - rrtmg_lw.nc                               (longwave radiation data)
  - ECHAM6_CldOptProps.nc                     (cloud optical properties)
  - mozart_coord.nc                           (MOZART coordinate mapping)
  - Linoz2004Br.dat                           (ozone loss rates)
  - Simnoy2002.dat                            (NOx-related chemistry data)
  - FJX_j2j.dat, FJX_j2j_extended.dat         (photolysis transition data)
  - FJX_scat-aer.dat, FJX_scat-cld.dat,
    FJX_scat-ssa.dat, FJX_scat-UMa.dat        (photolysis scattering data)
  - FJX_spec.dat, FJX_spec_extended.dat,
    FJX_spec_extended_lyman.dat               (photolysis spectral data)
  - atmos_std.dat, atmos_h2och4.dat           (standard atmosphere and CH₄/H₂O absorption)
  - tracers_chemtracer_simple_OH.xml          (OH chemistry tracer configuration)
  - exp.testsuite.nwp_oh_chemistry_base       (runscript)
  - README.txt                                (this file)

Model setup and configuration:
------------------------------
  - Domain: Global (R02B05)
  - Resolution: ~80 km
  - Model type: ATMO
  - Start date: 2013-11-05T00:00:00
  - Forecast length: 1 day
  - Time step: 360 seconds
  - Vertical levels: 90
  - Equation system: Non-hydrostatic (iequations=3)
  - Dynamics: Enabled (ldynamics=.TRUE.)
  - Transport: Enabled (ltransport=.TRUE.)
  - Chemistry: Enabled (lart_chem=.TRUE.)
  - Aerosols: Disabled (lart_aerosol=.FALSE.)
  - Radiation: Enabled (inwp_radiation=4)
  - Grid setup: Dynamics → R02B05, Radiation → R02B04
  - Restart interval: every 60 days
  - Checkpoint interval: P10D
  - Output variables: temperature, pressure, OH_Nconc, O1D_Nconc, ART_CHEMISTRY group
  - Output frequency: hourly (3600 seconds)

Description:
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This testcase performs a global ICON-ART simulation to investigate hydroxyl (OH) chemistry processes. It provides a simplified chemistry for testing the oxidation capacity of the atmosphere through reactive species such as OH and O1D and the tracer setup in 'tracers_chemtracer_simple_OH.xml'.

