data.exo

The data.exo file is used to set parameters for the physics used in expeRT/MITgcm.

A typical data.exo file may look like this:

C--   EXORAD interface parameter (namelist EXORAD_PARAMS):
# EXORAD_NEWTON :: flag to switch on/off simplfied radiative forcing
# EXORAD_FULL :: flag to switch on/off full radiative transfer
# EXORAD_LOW :: flag to enforce special treatment of lower layers
# EXORAD_TYPE :: flag to choose type of planet, GASY or ROCK (Char*4)
# EXORAD_DEEP_CONVERGENCE :: Use convergence acceleration or not (warning, only set if you really know what you do!)

 &EXORAD_PARAMS
 EXORAD_NEWTON =.FALSE.,
 EXORAD_FULL =.TRUE.,
 EXORAD_LOW =.FALSE.,
 EXORAD_TYPE ='GASY',
 EXORAD_DEEP_CONVERGENCE =.FALSE.,
 &

# SPONGE LAYER SETTING
# Rayleigh friction prescription to U and V wind field
# EXORAD_KTOP :: sets friction time scale (the same for both U and V)
#                [1/days-1]
# EXORAD_SIGMA_T :: Sets vertical pressure [Pa] for sponge layer
# EXORAD_PREF :: Reference pressure [Pa] for setting sponge layer. 1.0E6 means 1e-4 bar as the starting of the spongelayer (with sigma_T = 1.0E-10)
# EXORAD_DEITRICK_K_SPONGE :: Use the sponge layer magnitude description of Deitrick et al. (2019) instead of exorad description
# EXORAD_SPONGE_ZONAL :: Soft (True) or hard spongelayer (False)

 &EXORAD_SPONGE
 EXORAD_KTOP = 20.0,
 EXORAD_SIGMA_T=1.0E-10,
 EXORAD_PREF=1.0E6,
 EXORAD_SPONGE_ZONAL=.TRUE.
 EXORAD_DEITRICK_K_SPONGE=.FALSE.
 &

The EXORAD_PARAMS section sets flags for the physics that should be used in expeRT/MITgcm. If you want to use expeRT/MITgcm with full radiative transfer, you will need to set EXORAD_FULL to .TRUE. and EXORAD_NEWTON to .FALSE.. EXORAD_TYPE should always be GASY since ROCKY planets are not yet implemented in expeRT/MITgcm. EXORAD_LOW can be used to enforce temperature convergence to a specific temperature profile (as specified in data.exodeep). This method is described in more detail in Carone et al. (2020).

The EXORAD_SPONGE section is used to set the parameters of the sponge layer. There are two types of sponge layers implemented in expeRT/MITgcm: a soft and a hard sponge layer, where the soft spongelayer forces the zonal velocity towards its zonal mean instead of to zero (hard sponge layer). You can switch between those by using the EXORAD_SPONGE_ZONAL flag (.TRUE. uses the soft sponge layer, .FALSE. the hard). The magnitude of the sponge layer is set using EXORAD_KTOP.

Warning

If you encounter that your model crashs in the upper atmosphere due to weird behaviour in the upper atmosphere, you could consider using a stronger sponge layer (value for EXORAD_KTOP) and see if that helps.