Conversion

This page groups all conversions performed by i7aof.convert to avoid scattering details across multiple pages. It focuses on inputs, units, and algorithm‑specific configuration without repeating the end‑to‑end ordering from End‑to‑End Workflows.

Contents:

  1. thetao/so → ct/sa (TEOS‑10)

  2. ct/sa → TF (thermal forcing)

  3. ct/sa → thetao/so (back‑conversion)

1) thetao/so → ct/sa (TEOS‑10)

Convert CMIP thetao and so on the native model grid to TEOS‑10 conservative temperature (ct) and absolute salinity (sa).

  • Inputs: monthly Omon thetao, so on the native grid

  • Outputs: ct, sa on the same native grid and vertical coordinate

  • CLI: ismip7-antarctic-convert-cmip-to-ct-sa

  • Python: i7aof.convert.cmip_to_ct_sa

Units and conventions:

  • thetao: potential temperature, units degC or K (CF‑compliant). Ensure attributes are correct for the conversion path.

  • so: Practical Salinity (PSS‑78). If inputs are Absolute Salinity, convert to Practical or preprocess accordingly.

  • Vertical: provide a monotonic depth or pressure coordinate.

Configuration:

[convert_cmip]
time_chunk = 12          # months per compute chunk

Tuning:

  • Larger time_chunk reduces Python overhead but increases memory.

  • For large 3D grids, 6–12 months per chunk is a good starting point.

Outputs:

<workdir>/convert/<model>/<scenario>/Omon/ct_sa/*_{ct,sa}_native.nc

Validation:

  • Profiles show plausible ct and sa ranges.

  • No time gaps or duplicates; dimensions/chunks match downstream expectations.

Troubleshooting:

export I7AOF_DEBUG_TEOS10=1

Minimal example:

from i7aof.convert.cmip_to_ct_sa import convert_cmip_to_ct_sa

convert_cmip_to_ct_sa('CESM2-WACCM', 'historical', user_config_filename='my.cfg')

2) ct/sa → TF (thermal forcing)

Compute Thermal Forcing from CT/SA. For CMIP this uses bias‑corrected monthly CT/SA; for climatology, the extrapolated fields.

  • CMIP CLI: ismip7-antarctic-cmip-ct-sa-to-tf

  • Climatology CLI: ismip7-antarctic-clim-ct-sa-to-tf

  • Python: i7aof.convert.ct_sa_to_tf

Inputs and outputs:

  • CMIP input: <workdir>/biascorr/<model>/<scenario>/<clim>/Omon/ct_sa/*_biascorr_*.nc

  • CMIP output: <workdir>/biascorr/<model>/<scenario>/<clim>/Omon/ct_sa_tf0/*_{ct,sa,tf}_*.nc

  • Climatology input: <workdir>/extrap/climatology/<clim>/*_{ct,sa}_extrap.nc

  • Climatology output: <workdir>/extrap/climatology/<clim>/*_tf_extrap.nc

Notes:

  • Internally computes the in‑situ freezing point from salinity/pressure and derives TF accordingly.

  • Ensure bias correction is complete for both scenarios before running the CMIP TF step.

Validation:

  • TF should generally be positive in warm waters and near zero in near‑freezing conditions; spot‑check profiles.

Minimal examples:

from i7aof.convert.ct_sa_to_tf import cmip_ct_sa_to_tf, clim_ct_sa_to_tf

cmip_ct_sa_to_tf('CESM2-WACCM', 'ssp585', clim_name='zhou_annual_06_nov', user_config_filename='my.cfg')
clim_ct_sa_to_tf('zhou_annual_06_nov', user_config_filename='my.cfg')

3) ct/sa → thetao/so (back‑conversion)

Provide thetao/so from CT/SA for downstream consumers. For CMIP this is run on annual means and also carries TF; for climatology it produces static thetao/so from extrapolated CT/SA.

  • CMIP CLI: ismip7-antarctic-cmip-annual-ct-sa-to-thetao-so

  • Climatology CLI: ismip7-antarctic-clim-ct-sa-to-thetao-so

  • Python: i7aof.convert.ct_sa_to_thetao_so

Inputs and outputs:

  • CMIP input: <workdir>/biascorr/<model>/<scenario>/<clim>/Oyr/ct_sa_tf/*_ann.nc

  • CMIP output: <workdir>/biascorr/<model>/<scenario>/<clim>/Oyr/thetao_so_tf/*_{thetao,so,tf}_ann.nc

  • Climatology input: <workdir>/extrap/climatology/<clim>/*_{ct,sa}_extrap.nc

  • Climatology output: <workdir>/extrap/climatology/<clim>/*_{thetao,so}_extrap.nc

Notes:

  • Uses TEOS‑10 relationships to back‑convert; ensure metadata/units are consistent.

  • CMIP path requires annual averages to exist (see Annual Averages (CMIP)).

Minimal examples:

from i7aof.convert.ct_sa_to_thetao_so import (
    cmip_ct_sa_ann_to_thetao_so_tf, clim_ct_sa_to_thetao_so,
)

cmip_ct_sa_ann_to_thetao_so_tf(
    model='CESM2-WACCM',
    scenario='ssp585',
    clim_name='zhou_annual_06_nov',
    user_config_filename='my.cfg',
)

clim_ct_sa_to_thetao_so('zhou_annual_06_nov', user_config_filename='my.cfg')