Difference between revisions of "Continuum Database"
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Revision as of 10:37, 11 February 2025
As of February 2025, we have now implemented a new continuum database in the Generic PCM. The continuum files are available here: https://web.lmd.jussieu.fr/~lmdz/planets/LMDZ.GENERIC/datagcm/continuum_data/
Contents
File format and location
TBD
Units
TBD
List of continua in the database
Below we provide the list of continua included in the database, with some details on how they were computed.
CO2-CO2
The CO2-CO2 continuum file combines:
- the COA CIA band at 0-250cm-1 (Gruszka and Borysow, 1997), extrapolated down to 100K.
- All CIA and dimer bands listed in Tran et al. 2024 (see Table), using the functional formula for the shape and band intensity (as a function of temperature). Temperature dependency is extended from 100 to 800K.
N2-N2
The N2-N2 continuum file combines all data (roto-translational, fundamental and first overtone bands) from Karman+2019: https://hitran.org/cia/ (N2-N2_2021.cia file).
O2-O2
The O2-O2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (O2-O2_2018b.cia and O2-O2_theory_temp_2018.cia files).
CH4-CH4
The CH4-CH4 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (CH4-CH4_2011.cia file). Only a single CH4 CIA band has been characterized so far (see Borysow & Frommhold 1987).
H2O-H2O
The H2O-H2O continuum is taken and interpolated from the MT_CKD continuum v_4.0.1 (https://github.com/AER-RC/MT_CKD_H2O). The H2O-H2O MT_CKD continuum is frequently updated, but most of the time the changes are very minor.
Note that the H2O-H2O MT_CKD continuum includes CIA and dimer bands, but also the absorption from the far wing (anything that absorbs beyond +/- 25cm-1 of each H2O line) and the plinth (the absorption at +/- 25cm-1) of H2O monomers (broadened by H2O).
Note that give the assumption of the MT_CKD continuum (continuum above 25cm-1), it is required that a 25cm-1 cutoff is applied to the absorption by the H2O monomers, and that the plinth is removed.
H2-H2
The H2-H2 continuum file combines ...
TBD
We took the "equilibrium" file which is the most accurate choice in general for most of our giant planet (H2-rich atmospheres) applications. Differences between "equilibrium" and "norm" appear at temperatures << 100K.
CO2-H2
The CO2-H2 continuum file combines all data from Turbet+20, Mondelain+21 and Fakhardji+21.
CO2-CH4
The CO2-H2 continuum file is built from Turbet+20.
CO2-O2
The CO2-O2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (O2-CO2_2011.cia file) and data from Baranov et al. 2004 (digitized from Fig. 7).
O2-N2
The O2-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (O2-N2_2021.cia and O2-N2_theory_temp_2018.cia).
H2O-AIR (H2O-O2 / H2O-N2)
The H2O-AIR continuum is taken and interpolated from the MT_CKD continuum v_4.0.1 (https://github.com/AER-RC/MT_CKD_H2O)
HERE WE NEED TO ADD THE DISTINCTION BETWEEN H2O-O2 and H2O-N2 (additional CIA from Baranov) Note that the H2O-AIR MT_CKD continuum includes CIA and dimer bands, but also the absorption from the far wing (anything that absorbs beyond +/- 25cm-1 of each H2O line) and the plinth (the absorption at +/- 25cm-1) of H2O monomers (broadened by "air").
Note that "AIR" here corresponds to the present-day Earth mixture of O2 and N2. In practice in the model, we will use the H2O-AIR continuum for both H2O-O2 and H2O-N2 continuum.
Note that give the assumption of the MT_CKD continuum (continuum above 25cm-1), it is required that a 25cm-1 cutoff is applied to the absorption by the H2O monomers, and that the plinth is removed.
H2O-CO2
The H2O-CO2 continuum file was recalculated following the procedure described in Tran, Turbet et al. 2018 (using HITRAN 2016 line list modified with CO2-broadening coefficient) and extended up to 20,000cm-1. The temperature dependency was calculated using Ma & Tipping 1992 results (only from 0-10000cm-1, because we have no data above).
We also added the H2O-CO2 CIA band from Fleurbaey et al. 2022 (but the temperature dependency is not known).
Note that we followed the MT_CKD framework (continuum above 25cm-1), so it is required that a 25cm-1 cutoff is applied to the absorption by the H2O monomers, and that the plinth is removed.
CH4-N2
The CH4-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (N2-CH4_2011.cia file).
H2-N2
The H2-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (N2-H2_2011.cia).
H2-He
The H2-He continuum file combines ...
TBD
We took the "equilibrium" file which is the most accurate choice in general for most of our giant planet (H2-rich atmospheres) applications. Differences between "equilibrium" and "norm" appear at temperatures << 100K.
H2-CH4
The H2-CH4 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (H2-CH4_eq_2011.cia). We took the "equilibrium" file which is the most accurate choice in general for most of our giant planet (H2-rich atmospheres) applications. Differences between "equilibrium" and "norm" appear at temperatures << 100K.
Words of caution
TBD
