GC5 central configuration

[MartinDix]

Try coupled and AMIP runs with the Met Office GC5 central configuration. This has lower climate sensitivity. Is the initial TOA radiative balance better?

See also #34 for attempts to improve radiation balance.

[MartinDix]

https://code.metoffice.gov.uk/trac/gmed/ticket/699 points to an GC5 central N96ORACA1 PI control suite u-dp657 using um vn13.8, with standard GC5 u-dk922.

Differences in physics
https://code.metoffice.gov.uk/trac/roses-u/changeset?reponame=&new=318839%40d%2Fp%2F6%2F5%2F7%2Ftrunk&old=318831%40d%2Fp%2F6%2F5%2F7%2Ftrunk

Are there changes to parameters here that aren't in vn13.1?

[MartinDix]

Changes for GC5 central in a vn12.2 suite u-dm675
https://code.metoffice.gov.uk/trac/roses-u/changeset?reponame=&new=308779%40d%2Fm%2F6%2F7%2F5%2Ftrunk&old=308761%40d%2Fm%2F6%2F7%2F5%2Ftrunk

Build has extra branches

jules_sources=branches/dev/martinbest/vn6.3_MO_buoyancy_calc@22879
             =branches/dev/johnrostron/vn6.3_GA9PPE_extendranges@22966
             =branches/dev/stevenrumbold/vn6.3_albedo_whitecap@27716
um_sources=branches/dev/martinwillett/vn12.2_ModMidPert@107867
          =branches/dev/martinwillett/vn12.2_BlackCarbonRho1900@107868
um_sources=branches/dev/martinwillett/vn12.2_ModMidPert@107867
          =branches/dev/martinwillett/vn12.2_BlackCarbonRho1900@107868
          =branches/dev/johnrostron/vn12.2_GA9PPE@108907
          =branches/dev/stevenrumbold/vn12.2_Seawater_DMS_flux_hard_limit@125971

which need to be checked.

[kieranricardo]

@MartinDix unfortunately GC5 central params makes radiation balance significantly worse (swapped to GC5 central at year 50)

[MartinDix]

There should be Met Office runs showing the TOA radiation for the all the GC5 central candidate experiments.

GC5 central is based on the P01 set of parameters described here, https://code.metoffice.gov.uk/trac/gmed/ticket/670. Base run (u-cz982) had TOA energy balance of ~ + 1.0 in a PI control, so perhaps ~ 2 in a PD control.

There was extra tuning to reduce the imbalance but it's not easy to trace it through. Some of the tuning parameters aren't in the namelists at vn13.0 so it might be better to move to an updated code. E.g. u-cz982 at vn12.2 uses an extra branch and defines ent_fac_sh=1.95 which we don't currently have.

[kieranricardo]

I missed changes in f0_io, nl0_io, and tupp_io - not sure what these do but they do but might help!

[MartinDix]

These are all JULES vegetation parameters so I don't expect they will have much effect on the radiation.

[access-hive-bot]

This issue has been mentioned on ACCESS Hive Community Forum. There might be relevant details there:

https://forum.access-hive.org.au/t/access-cm3-technical-meeting-minutes/5429/2