Update MT_CKD continuum

[nichollsh]

Migrated from nichollsh/SOCRATES#11

We use MT_CKD 4.1.1 as the nominal water continuum in spectral files at the moment.
We should update to the latest version (4.2 or 4.3?), which comes with some fixes.

These continuum changes lead to a significant decrease in downwelling longwave flux at the surface for moist atmospheres and a modest increase in outgoing longwave radiation. The increased fraction of surface-leaving radiation that escapes to space leads to a notable increase (∼5–10%) in climate feedback, implying that climate simulations that use the new infrared window continuum will show somewhat less warming than before

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024JD041366
https://github.com/AER-RC/MT_CKD_H2O/releases/tag/4.3

[nichollsh]

Original comment by @timlichtenberg on 2025-05-29T09:22:28Z\n\nShould this go in hand with some additional molecules to be incorporated into the spectral files and also the extension of some opacities toward shorter wavelenghts?

[nichollsh]

Original comment by @nichollsh on 2025-05-29T10:11:23Z\n\nYes absolutely - I was thinking the same thing.

We could build an updated collection of files. It's still useful to have restricted ones, because they have a lower computational load (e.g. pure steam). We can have something like Honeyside with the usual volatiles. Would also be a good time to integrate some rock vapour species.

Integrating UV data from MPI makes sense.

Could also explore different numbers of bands (8, 64 and 128 band cases would be good)

[nichollsh]

Original comment by @timlichtenberg on 2025-05-29T10:30:10Z\n\nWhen doing this, would it be possible to extend the document of your scripts a bit more to enable more people to use them? Even though we try to be as comprehensive as possible each time, I think we will have to re-do this time and time again as we are making the code(s) more general.

[nichollsh]

Original comment by @timlichtenberg on 2025-05-29T10:30:25Z\n\nWhich species were you thinking about in terms of volatiles and refractories?

[nichollsh]

Original comment by @nichollsh on 2025-05-29T10:46:24Z\n\nAlso while we are at it, see also https://github.com/nichollsh/SOCRATES/issues/12

[nichollsh]

Original comment by @nichollsh on 2025-05-29T10:48:08Z\n\n> When doing this, would it be possible to extend the document of your scripts a bit more to enable more people to use them? Even though we try to be as comprehensive as possible each time, I think we will have to re-do this time and time again as we are making the code(s) more general.

I agree that this would be good to do. Made an issue: https://github.com/nichollsh/SOCRATES/issues/13
There's also information on the AGNI wiki which could be incorporated: https://nichollsh.github.io/AGNI/dev/model/#Radiative-transfer

[nichollsh]

Original comment by @nichollsh on 2025-05-29T10:51:09Z\n\n> Which species were you thinking about in terms of volatiles and refractories?

Makes sense to include the volatiles from PROTEUS as the standard set, which are mostly covered by Honeyside currently: "H2O", "CO2", "O2", "H2", "CH4", "CO", "N2", "NH3", "S2", "SO2", "H2S".

Could potentially add phosphorous-bearing species (PS, PH3)?

Go-to refractories would be "SiO", "SiO2", "MgO", "FeO2". Could be benchmarked against Alex's "Rocks" spectral file.

This paper might also be a useful reference: https://arxiv.org/abs/2503.15844

[nichollsh]

Original comment by @timlichtenberg on 2025-05-29T18:28:24Z\n\nSound all good and reasonable. Some more for thinking about (this is only checking what would make sense, not if the abundances are available):

• CN, HCN
• PO, PN (if the background gas is different)
• SiH4
• Si, SiO, SO2 as a series (from reduced to oxidized)
• FeH, Fe, FeO, FeO2 as a series (from reduced to oxidized)
• Na, NaO
• at some point it may be interesting to add all purported biosignature gases: https://arxiv.org/pdf/2504.12946