Difference between revisions of "Continuum Database"

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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/  
+
As of February 2025, we have now implemented a new continuum database in the Generic PCM. The continuum files are provided here (please contact Martin if you have any suggestion, question, new additions you want to make): https://web.lmd.jussieu.fr/~lmdz/planets/generic/datagcm/continuum/
 +
As of April 2026, the continuum database is now splitted in two parts : a CIA database and a far wing database. Below we list the CIA tables of the database. The line far wing database is constructed from line lists and experimental correction factors, using codes like SpeCT or kspectrum.
 +
 
 +
= File format and location =
 +
 
 +
The files are stored here: https://web.lmd.jussieu.fr/~lmdz/planets/generic/datagcm/continuum/ in two sections : a CIA (collision-induced absorption) database and a line far wing database
 +
 
 +
The first line of the file (header) list the grid of temperatures.
 +
For the next lines, the first column corresponds to the wavenumber (in cm-1), then the absorption coefficient at the first temperature, etc.
 +
 
 +
Note : We have stored all the ancient continuum files (e.g., HITRAN format) in the https://web.lmd.jussieu.fr/~lmdz/planets/generic/datagcm/continuum/CIA_data/pre-2025_continua/ directory.
 +
 
 +
= Units =
 +
 
 +
The continuum absorption a_normXY units of the tables is cm-1 amagat-2. This is a standard units for continuum absorption.
 +
 
 +
The absorption coefficient a_XY (m-1) </math> for molecules X and Y can then be computed from the following equation:
 +
 
 +
  a_XY = 100.0 * a_normXY * amagat_X * amagat_Y !
 +
 
 +
  with amagat_X = (273.15/T)*(P_X/101325.0)
 +
  with amagat_Y = (273.15/T)*(P_Y/101325.0)
 +
 
 +
with T the temperature (in K), P_X and P_Y the partial pressure of the molecules X and Y (in Pascal units).
 +
 
 +
Note : The HITRAN continuum files are in cm^5 molecule-2 units. You can convert HITRAN continuum data into cm-1 amagat-2 by dividing them by <math>1.385 \times  10^{-39}</math>
 +
 
 +
= List of collision-induced absorption (CIA) 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 ==
 
== CO2-CO2 ==
Line 5: Line 34:
 
[[File:CO2-CO2 CIA new database fev2025.png|thumb|CO2-CO2 CIA new database fev2025.png]]
 
[[File:CO2-CO2 CIA new database fev2025.png|thumb|CO2-CO2 CIA new database fev2025.png]]
  
 +
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.
  
 
[[Category:Generic-Model]]
 
[[Category:Generic-Model]]
 +
 +
== 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).
 +
 +
The temperature dependency is extrapolated from 70 to 500K.
 +
 +
[[File:N2-N2 CIA new database fev2025.png|thumb|N2-N2 CIA new database fev2025.png]]
 +
 +
== 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).
 +
 +
The temperature dependency is extrapolated from 100 to 400K.
 +
 +
[[File:O2-O2 CIA new database fev2025.png|thumb|O2-O2 CIA new database fev2025.png]]
 +
 +
== 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).
 +
 +
The temperature dependency is extrapolated from 40 to 500K.
 +
 +
[[File:CH4-CH4 CIA new database fev2025.png|thumb|CH4-CH4 CIA new database fev2025.png]]
 +
 +
== 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.
 +
 +
[[File:H2O-H2O CIA new database fev2025.png|thumb|H2O-H2O CIA new database fev2025.png]]
 +
 +
== H2-H2 ==
 +
 +
The H2-H2 continuum file combines the H2-H2 file previously used for temperate-to-hot gas giants (H2-H2_2011_extended.cia.txt extended to wavelengths > 10,000cm-1 and temperatures up to 10,000K ; work done by Lucas Teinturier using codes provided by Bruno Bézard) and the (low-temperature) H2-H2 file used for solar system giant planets (provided by Gwenael Milcareck). The first file is used for T>400K and the second file for T<=400K.
 +
 +
We took the "equilibrium" files 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.
 +
 +
[[File:H2-H2 CIA new database fev2025.png|thumb|H2-H2 CIA new database fev2025.png]]
 +
 +
== CO2-H2 ==
 +
 +
The CO2-H2 continuum file combines all data from Turbet+20, Mondelain+21 and Fakhardji+21.
 +
 +
The temperature dependency is extrapolated from 100 to 800K.
 +
 +
[[File:CO2-H2 CIA new database fev2025.png|thumb|CO2-H2 CIA new database fev2025.png]]
 +
 +
== CO2-CH4 ==
 +
 +
The CO2-H2 continuum file is built from Turbet+20.
 +
 +
The temperature dependency is extrapolated from 100 to 800K.
 +
 +
[[File:CO2-CH4 CIA new database fev2025.png|thumb|CO2-CH4 new database fev2025.png]]
 +
 +
== 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).
 +
 +
The temperature dependency is extrapolated from 100 to 600K.
 +
 +
[[File:CO2-O2 CIA new database fev2025.png|thumb|CO2-O2 new database fev2025.png]]
 +
 +
== 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).
 +
 +
The temperature dependency is extrapolated from 100 to 500K.
 +
 +
[[File:O2-N2 CIA new database fev2025.png|thumb|O2-N2 new database fev2025.png]]
 +
 +
== 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)
 +
 +
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.
 +
 +
'''In practice, we take the H2O-O2 continuum equal to the MT_CKD H2O-AIR continuum. The H2O-N2 continuum is taken equal to the H2O-AIR MT_CKD continuum + the CIA band of Baranov+2012/Hartmann+2017 near 2400cm-1.'''
 +
 +
[[File:H2O-O2 CIA new database fev2025.png|thumb|H2O-AIR/H2O-O2 new database fev2025.png]]
 +
 +
[[File:H2O-N2 CIA new database fev2025.png|thumb|H2O-N2 new database fev2025.png]]
 +
 +
== 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.
 +
 +
[[File:H2O-CO2 CIA new database fev2025.png|thumb|H2O-CO2 new database fev2025.png]]
 +
 +
== CH4-N2 ==
 +
 +
The CH4-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (N2-CH4_2011.cia file).
 +
 +
The temperature dependency is extrapolated from 40 to 600K.
 +
 +
[[File:CH4-N2 CIA new database fev2025.png|thumb|CH4-N2 new database fev2025.png]]
 +
 +
== H2-N2 ==
 +
 +
The H2-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (N2-H2_2011.cia).
 +
 +
The temperature dependency is extrapolated from 40 to 600K.
 +
 +
[[File:H2-N2 CIA new database fev2025.png|thumb|H2-N2 new database fev2025.png]]
 +
 +
== H2-He ==
 +
 +
The H2-He continuum file combines the H2-He file previously used for temperate-to-hot gas giants (H2-He_2011.cia file provided in HITRAN) and the (low-temperature) H2-He file used for solar system giant planets (provided by Gwenael Milcareck ; file name was H2-He_eq_0-15000cm-1_40-400K.cia) and that we extended up to 20,000cm-1. The first file is used for T>400K and the second file for T<=400K.
 +
 +
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.
 +
 +
[[File:H2-He CIA new database fev2025.png|thumb|H2-He new database fev2025.png]]
 +
 +
== 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.
 +
 +
The temperature dependency is extrapolated from 40 to 600K.
 +
 +
[[File:H2-CH4 CIA new database fev2025.png|thumb|H2-CH4 new database fev2025.png]]
 +
 +
= Words of caution =
 +
 +
Beware that some of the correlated-k tables do already include some of the continuum terms here. For instance CO2_H2Ovar correlated-k table (and most of the CO2-thick historical correlated-k table) include the 0-250cm-1 CIA band and the Fermi doublet of CO2-CO2. For these "old" tables, we recommend that you switch back to the old continuum tables, to avoid counting some terms twice.
 +
 +
Recent tables (e.g. CO2-H2Ovar_2026) now don't include far wing absorption, and it can be added directly in the GCM using continuum_far_wing = .true.

Latest revision as of 11:43, 13 April 2026

As of February 2025, we have now implemented a new continuum database in the Generic PCM. The continuum files are provided here (please contact Martin if you have any suggestion, question, new additions you want to make): https://web.lmd.jussieu.fr/~lmdz/planets/generic/datagcm/continuum/ As of April 2026, the continuum database is now splitted in two parts : a CIA database and a far wing database. Below we list the CIA tables of the database. The line far wing database is constructed from line lists and experimental correction factors, using codes like SpeCT or kspectrum.

File format and location

The files are stored here: https://web.lmd.jussieu.fr/~lmdz/planets/generic/datagcm/continuum/ in two sections : a CIA (collision-induced absorption) database and a line far wing database

The first line of the file (header) list the grid of temperatures. For the next lines, the first column corresponds to the wavenumber (in cm-1), then the absorption coefficient at the first temperature, etc.

Note : We have stored all the ancient continuum files (e.g., HITRAN format) in the https://web.lmd.jussieu.fr/~lmdz/planets/generic/datagcm/continuum/CIA_data/pre-2025_continua/ directory.

Units

The continuum absorption a_normXY units of the tables is cm-1 amagat-2. This is a standard units for continuum absorption.

The absorption coefficient a_XY (m-1) </math> for molecules X and Y can then be computed from the following equation: 

 a_XY = 100.0 * a_normXY * amagat_X * amagat_Y ! 

 with amagat_X = (273.15/T)*(P_X/101325.0)
 with amagat_Y = (273.15/T)*(P_Y/101325.0)

with T the temperature (in K), P_X and P_Y the partial pressure of the molecules X and Y (in Pascal units).

Note : The HITRAN continuum files are in cm^5 molecule-2 units. You can convert HITRAN continuum data into cm-1 amagat-2 by dividing them by \(1.385 \times 10^{-39}\)

List of collision-induced absorption (CIA) 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

CO2-CO2 CIA new database fev2025.png

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).

The temperature dependency is extrapolated from 70 to 500K.

N2-N2 CIA new database fev2025.png

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).

The temperature dependency is extrapolated from 100 to 400K.

O2-O2 CIA new database fev2025.png

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).

The temperature dependency is extrapolated from 40 to 500K.

CH4-CH4 CIA new database fev2025.png

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.

H2O-H2O CIA new database fev2025.png

H2-H2

The H2-H2 continuum file combines the H2-H2 file previously used for temperate-to-hot gas giants (H2-H2_2011_extended.cia.txt extended to wavelengths > 10,000cm-1 and temperatures up to 10,000K ; work done by Lucas Teinturier using codes provided by Bruno Bézard) and the (low-temperature) H2-H2 file used for solar system giant planets (provided by Gwenael Milcareck). The first file is used for T>400K and the second file for T<=400K.

We took the "equilibrium" files 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-H2 CIA new database fev2025.png

CO2-H2

The CO2-H2 continuum file combines all data from Turbet+20, Mondelain+21 and Fakhardji+21.

The temperature dependency is extrapolated from 100 to 800K.

CO2-H2 CIA new database fev2025.png

CO2-CH4

The CO2-H2 continuum file is built from Turbet+20.

The temperature dependency is extrapolated from 100 to 800K.

CO2-CH4 new database fev2025.png

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).

The temperature dependency is extrapolated from 100 to 600K.

CO2-O2 new database fev2025.png

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).

The temperature dependency is extrapolated from 100 to 500K.

O2-N2 new database fev2025.png

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)

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.

In practice, we take the H2O-O2 continuum equal to the MT_CKD H2O-AIR continuum. The H2O-N2 continuum is taken equal to the H2O-AIR MT_CKD continuum + the CIA band of Baranov+2012/Hartmann+2017 near 2400cm-1.

H2O-AIR/H2O-O2 new database fev2025.png
H2O-N2 new database fev2025.png

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.

H2O-CO2 new database fev2025.png

CH4-N2

The CH4-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (N2-CH4_2011.cia file).

The temperature dependency is extrapolated from 40 to 600K.

CH4-N2 new database fev2025.png

H2-N2

The H2-N2 continuum file combines all data from Karman+2019: https://hitran.org/cia/ (N2-H2_2011.cia).

The temperature dependency is extrapolated from 40 to 600K.

H2-N2 new database fev2025.png

H2-He

The H2-He continuum file combines the H2-He file previously used for temperate-to-hot gas giants (H2-He_2011.cia file provided in HITRAN) and the (low-temperature) H2-He file used for solar system giant planets (provided by Gwenael Milcareck ; file name was H2-He_eq_0-15000cm-1_40-400K.cia) and that we extended up to 20,000cm-1. The first file is used for T>400K and the second file for T<=400K.

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-He new database fev2025.png

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.

The temperature dependency is extrapolated from 40 to 600K.

H2-CH4 new database fev2025.png

Words of caution

Beware that some of the correlated-k tables do already include some of the continuum terms here. For instance CO2_H2Ovar correlated-k table (and most of the CO2-thick historical correlated-k table) include the 0-250cm-1 CIA band and the Fermi doublet of CO2-CO2. For these "old" tables, we recommend that you switch back to the old continuum tables, to avoid counting some terms twice.

Recent tables (e.g. CO2-H2Ovar_2026) now don't include far wing absorption, and it can be added directly in the GCM using continuum_far_wing = .true.

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