Support Sturm1997 snow parameterisation

[s-poll]

Hi all,

there seems to be high snow amounts in the euro-11 eCLM simulation. The issue is known for CLM5.0. There is a fix using Sturm1997 snow parameterisation, which is also the default from CLM v5.1 onwards.

More information can be found at ctsm5.1.dev174

Maybe this is also related to #90 and #66.

Could we please update the CLM version, maybe directly to v5.4?

[kvrigor]

Fixing the eCLM snow model only requires these PRs, which were suggested by Heidrun Matthes when we worked on Helmholtz funding proposal last year (which we unfortunately didn't get):

• Changes to improve vegetation health at high latitudes
• User control over snow thermal conductivity scheme over glaciers

These fixes were initiated in response to the ff. findings by Heidrun's group:

Damseaux, A., Matthes, H., Dutch, V. R., Wake, L., and Rutter, N.: Impact of snow thermal conductivity schemes on pan-Arctic permafrost dynamics in the Community Land Model version 5.0, The Cryosphere, 19, 1539–1558, https://doi.org/10.5194/tc-19-1539-2025, 2025.

[jjokella]

I think we can split this into two issues

• updated parameterisation: handled as described in @kvrigor's comment
• scheme for updating the CLM underlying eCLM: possibly related to eCLM branch with full history from CLM5, CIME, FATES, MOSART #96