MartinDix
commented
1 day ago The Met Office n96orca1 PI control, e.g. u-ct598, instead tunes some cloud ice detrainment parameters. Compared to the AMIP configuration we've used until now changed parameters are
| Parameter | AMIP | PI control |
|---|---|---|
| cff_spread | 1.0e-5 | 1.0e-10 |
| tice | 263.15 | 253.15 |
| starticeTKelvin | 263.15 | 265.15 |
| alliceTdeg | -20 | -32 |
| two_d_fsd_factor | 1.65 | 1.67 |
Latest CM3 runs (e.g.
cm3-run-16-09-2024) have a net TOA energy flux around 2.7 W/m^2 initially.Met Office GC5 AMIP runs were tuned to give the desired radiation balance at N216, not N96. The tuning is described at https://code.metoffice.gov.uk/trac/gmed/wiki/ticket/573/TicketDetails describes the radiation tuning of the N216 version.
This is an extract of the table near the end of https://code.metoffice.gov.uk/trac/gmed/wiki/ticket/577/TicketSensitivityTests
RC3 is almost the same as the final version, except for an update to the boundary layer buoyancy https://code.metoffice.gov.uk/trac/jules/ticket/1242.
Alejandro Bodas's presentation at the 2023 Momentum Workshop says they retuned the GC5-N96ORCA1 PI control aiming at rsut=99, rlut=240.5, close to CERES EBAF4 values (because UKESM suggested PI and current were pretty close). Used
two_d_fsd_factor = 1.70, cape_timescale =2700 sin place of standardtwo_d_fsd_factor=1.65 cape_timescale=1800.0, though not clear if this is the final value.