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…onductive flux limits to CM2
Co-authored-by: Kieran Ricardo <u5824685@anu.edu.au>
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hey @anton-seaice, can you give this a look over before I make a PR into the CICE-consortium icepack? 👀 |
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I will look properly, but i think split this into two changes, one for hs_min and one for the cap_fluxes stuff
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@anton-seaice yeah good point, I've remove the hs_min configurable stuff now |
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In general - are these changes due to undiscovered issues with the way the UM -> CICE coupling works? Or are these changes unavoidable ? Well need to have a good justification to get these into the consortium repo
(Oh and some extra notes in the documentation_
columnphysics/icepack_flux.F90
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| character(len=*),parameter :: subname='(set_sfcflux)' | ||
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| raicen = c1 | ||
| raicen = c1 / aicen |
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So this is the same as line 360 now?
The comment says (When in standalone mode, fluxes ! are input as per ice area.) does that mean there is a standalone icepack using this subroutine, or the comment is out of date ?
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I've changed this to use an #idfef(ACCESS3_CICE) (which is now defined in CICE)
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| real (kind=dbl_kind) :: fcondtopn_solve | ||
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| real (kind=dbl_kind), parameter :: ratio_Wm2_m = 1000.0, cold_temp_flag = c0 - 60.0 |
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I guess we should put these in icepack_parameter.F90 , and add them to icepack_init_parameters
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| !======================================================================= | ||
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| function cap_conductive_flux(nilyr, nslyr, fcondtopn, hin, zTsn, zTin, hslyr) result(fcondtopn_solve) |
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should this be a subroutine? is there a particular reason to have a function ?
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this just returns a single float, so a function felt cleaner to me here.
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| else ! ktherm | ||
| fcondtopn_solve = cap_conductive_flux(nilyr, nslyr, fcondtopn, hin, zTsn, zTin, hslyr) | ||
| fcondtopn_extra = fcondtopn - fcondtopn_solve |
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Does this need an if ( .not. calc_Tsfc ) ?
If CICE is internally calculating the conductive flux then there is hopefully no issue that would mean the flux needs capping ?
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good catch. this shouldn't be doing anything if calc_Tsfc=true bc fcondtop will be calculated in the following routine, but we should be needlessly capping a flux that potentially isn't even defined.
| !======================================================================= | ||
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| function cap_conductive_flux(nilyr, nslyr, fcondtopn, hin, zTsn, zTin, hslyr) result(fcondtopn_solve) | ||
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This will need a description of some form
Co-authored-by: Anton Steketee <79179784+anton-seaice@users.noreply.github.com>
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@anton-seaice nah these issues have been known for a long time, and CM2 actually had these same changes. If the fluxes are too large, then the ice can keep going above the melting point, and resetting infinitely - never converging! These code changes basically reduce the conductive flux if this happens, and pass the extra energy to the ocean. There's some mention of this in the Icepack documentation, e.g. second paragraph here: https://cice-consortium-icepack.readthedocs.io/en/main/science_guide/sg_boundary_forcing.html And towards of this section here: https://cice-consortium-icepack.readthedocs.io/en/main/science_guide/sg_thermo.html#bitz-and-lipscomb-thermodynamics-ktherm-1 |
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This looks good Kieran - feel free to submit upstream, where I expect there will be some questions about the details. I can run the Icepack repro tests after a first review. Note that this is already covered in the documentation - and give it a clear description (e.g. something like ("Cap effective conductive when |
| ! Alex West: return this energy to the ocean | ||
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| dqmat_sn = (zTsn(k)*cp_ice - Lfresh)*rhos - zqsn(k) | ||
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| ! Alex West: If this is the second time in succession that Tsn(1) has been | ||
| ! reset, tell the solver to reduce the forcing at the top, and | ||
| ! pass the difference to the array enum where it will eventually | ||
| ! go into the ocean | ||
| ! This is done to avoid an 'infinite loop' whereby temp continually evolves | ||
| ! to the same point above zero, is reset, ad infinitum |
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This will need a neater comment as well
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This introduces changes when running icepack in
calc_tsfc=.false.mode for coupling with fluxes supplied from an atmosphere model.Developer(s):
@kieranricardo @blimlim
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When
calc_tsfc=.false.the conductive flux is now capped, and it is also reduced duringtemperature_changesif the thermo solve is struggling to converge. The excess flux is accounted for in the energy calculations.Also,
hs_minis made configurable. A larger value than the default is needed for numerical stability when run withcalc_tsfc=.false..