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Generalise rofi spreading #23

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Generalise rofi spreading #23

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18211b0
generalise rofi spreading to arbtitrary components, and add into post…
kieranricardo May 19, 2026
17dd52b
add missing variable declarations and imports
kieranricardo May 19, 2026
51a7084
update rofi field spreading name
kieranricardo May 25, 2026
1b264eb
share more code between post rof and post atm, add in `spread_rofi_*h…
kieranricardo Jun 16, 2026
1510809
remove uneccesary changes
kieranricardo Jun 16, 2026
5797ecb
add subroutine argument comment
kieranricardo Jun 16, 2026
bc1e91b
declare variables
kieranricardo Jun 16, 2026
85a2b4a
declare variables
kieranricardo Jun 16, 2026
93501fc
Update mediator/med_phases_post_rof_mod.F90
kieranricardo Jun 17, 2026
effb2d7
Update mediator/med_phases_post_rof_mod.F90
kieranricardo Jun 17, 2026
25aeed3
Update mediator/med_phases_post_atm_mod.F90
kieranricardo Jun 17, 2026
8eff754
review response
kieranricardo Jun 17, 2026
acfb661
review response
kieranricardo Jun 17, 2026
076447a
make spreading_initialized flag a local variable
kieranricardo Jun 17, 2026
2d58418
apply spreading to input field (pre-mapping)
kieranricardo Jun 29, 2026
ec42ea4
fix - use src_areas
kieranricardo Jun 29, 2026
ccb19c2
various fixes
kieranricardo Jun 29, 2026
e34215c
update comp in post atm
kieranricardo Jun 29, 2026
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14 changes: 14 additions & 0 deletions mediator/med_phases_post_atm_mod.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,9 @@ module med_phases_post_atm_mod

character(*), parameter :: u_FILE_u = &
__FILE__
character(len=9), parameter :: fields_to_spread_runoff(1) = &
['Faoa_rofi']

@anton-seaice anton-seaice Jun 16, 2026

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did rofi and rofl get seperated elsewhere ?

@kieranricardo kieranricardo Jun 17, 2026

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In access-esm rofl only contains the river runoff, and rofi contains both the iceberg basal and calving melt fluxes. The spreading here simultaneously does your calving flux spreading + a coastal distribution for the basal melt. Is that what you meant?

@anton-seaice anton-seaice Jun 17, 2026

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Oh - ah, I think it's better to have seperate steps in the mediator for basal and iceberg right ?

basal fraction, gets remapped with a fixed remapping weights file to put it along coastlines

and iceberg gets spread like this change

@anton-seaice anton-seaice Jun 18, 2026

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It would be great if what was done was as close as possible consistent with OM3.

So that would mean splitting the iceberg and basal proportions before they leave the mediator. And having separate rofi/rofl fields to correspond to the MOM fields. It's relatively clear in the MOM diagnostics that rofi should be for the iceberg fraction - e.g. https://github.com/ACCESS-NRI/access-om3-configs/blob/b14a2797812531d5b4728f04cd67dcee19bfe439/docs/available_diags.000000#L4548, although less clear about the liquid proportion (e.g. there are lrunoff_glc fields available which OM3 doesn't use). Having separate fields for rofi and rofl means the rofi spreading input file can be the same across the two models. It also supports future/ongoing work to figure out how to spread the basal melt fraction vertically

The proposal to put the basal melt component in rofi by having a single pattern with 50% of the volume at the coastline will continue to give issues with supercooled water & excess sea ice from the large latent heat flux at the coastlines.

@kieranricardo kieranricardo Jun 23, 2026

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Unfortunately this will be tricky! The coupled model needs to have energy balance, and ignoring the basal melt latent heat will give us a persistent +0.05 W/m^2 (averaged over the entire earth) bias.

The latent heat at the coastal point doesn't seem to cause issues, the maximum sea-ice thickness matches OM3. If it does cause issues in the future we can add this splitting in and put the latent heat somewhere else.

But either way I don't think this will change the spreading routine itself, just how and where we apply it in post_atm. Shall we leave this as is, and change how we apply the spreading routine to CM3 if needed in a future PR?

@anton-seaice anton-seaice Jun 25, 2026

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Isn't the atmosphere just a really basic glacier model ? 😅

Well probably need to split the rofl field from datm into rivers / basal at some point, so would be good if the same name could be used for both cases .

@dougiesquire dougiesquire Jun 25, 2026

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Well probably need to split the rofl field from datm into rivers / basal at some point, so would be good if the same name could be used for both cases .

Yeah. My thinking is that we want specific logic in MOM for the basal flux (latent heat and potentially other things, e.g. insertion at depth). I feels like the implementation will be cleaner with a new field.

@kieranricardo kieranricardo Jun 29, 2026 •
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Having an additional field in MOM, and spreading the freshwater and latent heat fluxes at depth sounds like the ideal approach.

We need the latent heat flux in the coupled model, so the existing liquid field _rofl fields won't be suitable. For now, we could either keep basal melt in Foxx_rofi, or move it into Foxx_rofi_glc. I suggest that we do one of these two options for now, and coordinate between OM3 and CM3 in the future (once OM3 handles the latent heat from the basal melt).

How does this sound? I see this PR as mostly about generalising the spreading routine, and we can iron out the model specifics later on.

@anton-seaice anton-seaice Jun 30, 2026

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We need the latent heat flux in the coupled model, so the existing liquid field _rofl

We can/will update MOM to address this

Do you have a preferred name for the new field @dougiesquire ?

Maybe

Foax_rofb (b for basal?)

@dougiesquire dougiesquire Jun 30, 2026

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Foax_rofb (b for basal?)

Seems sensible to me



!-----------------------------------------------------------------------------
contains
Expand All @@ -35,6 +38,7 @@ subroutine med_phases_post_atm(gcomp, rc)
use med_utils_mod , only : chkerr => med_utils_ChkErr
use med_internalstate_mod , only : compocn, compatm, compice, complnd, compwav, coupling_mode
use perf_mod , only : t_startf, t_stopf
use med_phases_post_rof_mod, only: med_phases_post_rof_spread_rofi_field_bundle

! input/output variables
type(ESMF_GridComp) :: gcomp
Expand Down Expand Up @@ -125,6 +129,16 @@ subroutine med_phases_post_atm(gcomp, rc)
if (ChkErr(rc,__LINE__,u_FILE_u)) return
end if

if (trim(coupling_mode) == 'access-esm') then
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! in access-esm, runoff comes from the atmosphere component, so spreading of iceberg melt here
call med_phases_post_rof_spread_rofi_field_bundle( &
gcomp, fields_to_spread_runoff, &
is_local%wrap%FBImp(compatm,compatm), &
is_local%wrap%FBImp(compatm,compocn), &
compatm, compocn, rc)
if (ChkErr(rc,__LINE__,u_FILE_u)) return
end if

if (dbug_flag > 20) then
call ESMF_LogWrite(subname//' done', ESMF_LOGMSG_INFO)
end if
Expand Down
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