Building Opacity Tables - Revision history

Martin.turbet: /* Adding continuum opacities */

2026-04-13T09:40:21Z

‎Adding continuum opacities

Martin.turbet at 20:47, 6 February 2026

2026-02-06T20:47:32Z

Martin.turbet at 10:13, 30 April 2025

2025-04-30T10:13:56Z

Martin.turbet: /* Calculation of high-resolution spectra */

2025-04-30T10:06:53Z

‎Calculation of high-resolution spectra

Martin.turbet at 09:58, 30 April 2025

2025-04-30T09:58:40Z

Martin.turbet: /* Correlated-k table data unit and organization */

2025-04-30T09:53:16Z

‎Correlated-k table data unit and organization

Martin.turbet: /* Building correlated-k tables */

2025-04-30T09:45:57Z

‎Building correlated-k tables

Martin.turbet at 09:41, 30 April 2025

2025-04-30T09:41:58Z

Martin.turbet at 09:31, 30 April 2025

2025-04-30T09:31:29Z

Martin.turbet: /* Calculation of high-resolution spectra */

2025-04-30T09:00:59Z

‎Calculation of high-resolution spectra

@@ Line 67: / Line 67: @@
 == Adding continuum opacities ==
-Finally, you may want to add continuum opacities (CIA, dimer). We have a dedicated page for that: https://lmdz-forge.lmd.jussieu.fr/mediawiki/Planets/index.php/Continuum_Database
+Finally, you may want to add continuum opacities (CIA, dimer) and far wings, in case it is not included in your opacity correlated-k table. We have a dedicated page for that: https://lmdz-forge.lmd.jussieu.fr/mediawiki/Planets/index.php/Continuum_Database
 [[Category:Generic-Model]]

@@ Line 64: / Line 64: @@
 You can use exo-k to modify existing correlated-k tables.
 You can also use home-made Fortran or Python scripts to do that, provided here: https://svn.lmd.jussieu.fr/Planeto/trunk/LMDZ.GENERIC/utilities/correlatedk_utilities/scripts_read_corrk/
 [[Category:Generic-Model]]

@@ Line 32: / Line 32: @@
 Some people have calculated high-resolution spectra and provided them to the community. Below, we provide a list of the available databases:
 - ExoMOL : https://www.exomol.com
 - petitradtrans : https://petitradtrans.readthedocs.io/en/latest/content/available_opacities.html

← Older revision		Revision as of 10:06, 30 April 2025
Line 28:		Line 28:

	These tools (speCT, kspectrum, ...) should be used to compute grids of high-resolution spectra depending on temperature, pressure and mixing ratio values that encompass the expected pressure/temperature/mixing ratio that you want to simulate in your atmosphere.		These tools (speCT, kspectrum, ...) should be used to compute grids of high-resolution spectra depending on temperature, pressure and mixing ratio values that encompass the expected pressure/temperature/mixing ratio that you want to simulate in your atmosphere.
		+
		+	=== Databases of high-resolution spectra ===
		+
		+	Some people have calculated high-resolution spectra and provided them to the community. Below, we provide a list of the available databases:
		+	- ExoMOL : https://www.exomol.com
		+	- petitradtrans : https://petitradtrans.readthedocs.io/en/latest/content/available_opacities.html
		+
		+	ps: careful when you use these databases to check that the assumptions (e.g. line list, etc.) that were made are compatible with the type of atmospheres you want to simulate in the model.

	== Building correlated-k tables ==		== Building correlated-k tables ==

@@ Line 54: / Line 54: @@
 You can use exo-k to modify existing correlated-k tables.
 You can also use home-made Fortran or Python scripts to do that, provided here: https://svn.lmd.jussieu.fr/Planeto/trunk/LMDZ.GENERIC/utilities/correlatedk_utilities/scripts_read_corrk/
 [[Category:Generic-Model]]

@@ Line 41: / Line 41: @@
 === Correlated-k table data unit and organization ===
-* The units of correlated-k tables is cm^2/molec.
+* The units of correlated-k tables (corrk_gcm_IR.dat and corrk_gcm_VI.dat file) is cm^2/molec.
 * The format of correlated-k tables is (n_temperature, n_pressure, n_vmr, n_band, n_gauss)
 === Note on how to modify existing correlated-k tables ===

@@ Line 33: / Line 33: @@
 Once you have your grid of high-resolution spectra (for a grid of temperatures, pressures and possibly mixing ratios), you need to post-process the spectra to generate so-called "correlated-k" opacity tables. '''HERE WE NEED TO WRITE A PARAGRAPH (maybe a dedicated page?) to explain the motivations for using correlated-k tables'''
-Historically, we have been using home-made scripts (kdistribution / generate_kmatrix) to convert high-resolution spectra into correlated-k tables.
+=== Tools ===
 Since 2020, we now have a dedicated, reference python package developed by Jeremy Leconte, called ''exo-k'', that we routinely use to do this operation. We recommend all user to use exo-k for this step. Tutorials are provided on the exo-k webpage: https://perso.astrophy.u-bordeaux.fr/~jleconte/exo_k-doc/index.html
-describe the tools we used:
+=== Correlated-k table data unit and organization ===
 * The units of correlated-k tables is cm^2/molec.
@@ Line 47: / Line 45: @@
 === Note on how to modify existing correlated-k tables ===
 == Adding continuum opacities ==

@@ Line 5: / Line 5: @@
 * (2) convert these high-resolution spectra into correlated-k tables
 * (3) add continuum opacity tables
 == Calculation of high-resolution spectra ==
@@ Line 27: / Line 26: @@
 As of April 2025, speCT should be the reference code to use to compute high-resolution spectra for H2O, CO2 and N2. For the other gases, you should use kspectrum. In the coming years, speCT should be able to handle more and more gases so it is intended to eventually replace kspectrum.
 == Building correlated-k tables ==
 describe the tools we used:

@@ Line 5: / Line 5: @@
 * (2) convert these high-resolution spectra into correlated-k tables
 * (3) add continuum opacity tables
 == Calculation of high-resolution spectra ==
@@ Line 10: / Line 11: @@
 === Line Lists ===
-The first thing you need to compute high-resolution spectra is to get line lists of the molecules (and/or atoms) that you want to simulate in the atmosphere.
+The first thing you need to compute high-resolution spectra is to get line lists of the molecules (and/or atoms) that you want to simulate in your atmosphere.
-For temperate  planets (Earth, Mars, etc.), the best line lists are provided by HITRAN: https://hitran.org
+For temperate  planets (Earth, Mars, etc.), the best line lists are usually provided in HITRAN: https://hitran.org
-For hot planets (Venus, etc.), the best line lists are provided by HITEMP: https://hitran.org/hitemp/
+For hot planets (Venus, etc.), the best line lists are usually provided in HITEMP: https://hitran.org/hitemp/
-These two databases (HITRAN and HITEMP) however often miss some molecules, or some line list parameters. If you reach such problem, ExoMOL (https://www.exomol.com) can be a good resource. It is less reliable than HITRAN and HITEMP because it is based on theoretical calculations, but it can be extremely useful to get line list/parameters where HITRAN and HITEMP have no data.
+These two databases (HITRAN and HITEMP) however often miss some molecules, or some line list parameters (broadening coefficients, temperature dependencies, etc.). If you reach such problem, ExoMOL (https://www.exomol.com) can be a good resource to look at. It is less reliable than HITRAN and HITEMP because it is based on theoretical calculations, but it can be extremely useful to get line list/parameters where HITRAN and HITEMP have no data. For instance and for this reason, ExoMOL is often used to simulate opacity tables for hot, gas giant exoplanets.
 === Tools to generate high-resolution absorption spectra ===
@@ Line 21: / Line 22: @@
 Once you have your line lists for all the molecules/atoms you want to simulate, you need to use tools to compute high-resolution absorption spectra.
 Historically, we have been using the code ''k-spectrum'' to compute high-resolution spectra. We have stored an historical version of the code here: http://svn.lmd.jussieu.fr/KSPECTRUM/trunk/kspectrum/
-describe the tools we used :
+More recently, we have developed (Guillaume Chaverot et al.) a new tool, called speCT (linked to be added here soon), to produce high-resolution spectra. Compared to k-spectrum, this new code is much more efficient (written and parallelized more efficiently) and include more subtle spectroscopic effects (broadening coefficients for multiple collisional partners), which is essential if you want to use big line lists like HITEMP (that contain many, and more more lines and parameters).
-* k-spectrum
+As of April 2025, speCT should be the reference code to use to compute high-resolution spectra for H2O, CO2 and N2. For the other gases, you should use kspectrum. In the coming years, speCT should be able to handle more and more gases so it is intended to eventually replace kspectrum.
 == Building correlated-k tables ==
@@ Line 42: / Line 38: @@
 * The units of correlated-k tables is cm^2/molec.
 * The format of correlated-k tables is (n_temperature, n_pressure, n_vmr, n_band, n_gauss)
 == Adding continuum opacities ==

← Older revision		Revision as of 09:00, 30 April 2025
Line 7:		Line 7:

	== Calculation of high-resolution spectra ==		== Calculation of high-resolution spectra ==
		+
		+	=== Line Lists ===
		+
		+	The first thing you need to compute high-resolution spectra is to get line lists of the molecules (and/or atoms) that you want to simulate in the atmosphere.
		+
		+	For temperate planets (Earth, Mars, etc.), the best line lists are provided by HITRAN: https://hitran.org
		+	For hot planets (Venus, etc.), the best line lists are provided by HITEMP: https://hitran.org/hitemp/
		+
		+	These two databases (HITRAN and HITEMP) however often miss some molecules, or some line list parameters. If you reach such problem, ExoMOL (https://www.exomol.com) can be a good resource. It is less reliable than HITRAN and HITEMP because it is based on theoretical calculations, but it can be extremely useful to get line list/parameters where HITRAN and HITEMP have no data.
		+
		+	=== Tools to generate high-resolution absorption spectra ===
		+
		+	Once you have your line lists for all the molecules/atoms you want to simulate, you need to use tools to compute high-resolution absorption spectra.
		+
		+	Historically, we have been using the code ''k-spectrum'' to compute high-resolution spectra. We have stored an historical version of the code here: http://svn.lmd.jussieu.fr/KSPECTRUM/trunk/kspectrum/
		+
		+	More recently, we have developed (Guillaume Chaverot et al.) a new tool, called speCT (linked to be added here soon), to produce high-resolution spectra. Compared to k-spectrum, this new code is much more efficient (written and parallelized more efficiently), which is essential if you want to
		+
		+

	describe the tools we used :		describe the tools we used :