PR for updating icepack to version from OM3-0.4.0 (DO NOT MERGE) by blimlim · Pull Request #7 · ACCESS-NRI/Icepack

blimlim · 2025-04-16T02:28:27Z

Not to be merged

This PR describes the changes in updating the base of CM3's icepack version from 6703bc5 to 43ead56. If the changes are approved, I'll change the branch name from update-cm3-icepack to cm3-coupling-0.4.0.

This branch was created by rebasing cm3-coupling onto 43ead56.

Several conflicts came up in the merge. I'll record each of the conflicts here for the purpose of documentation. For review, I've separated them into more substantial conflicts, and much more straightforward ones where I'm more confident in my choice for resolution. Where relevant, I've tried to include some background on the upstream or local changes that caused the conflicts.

Conflicts

Clashes more likely to need review

Change of `hi_min` parameter

The minimum ice thickness hi_min was previously set in icepack_itd.F90, where it was given a default value and overwritten in specific cirumstances.

8fad768 on main moves its definition and default value to icepack_parameters.F90, making it definable in a CICE namelist. This includes for example the following changes in icepack_itd.F90:

+      use icepack_parameters, only: skl_bgc, z_tracers, hi_min
...

subroutine icepack_init_itd(hin_max)
...
-      hi_min = p01    ! minimum ice thickness allowed (m) for thermo
-                       ! note hi_min is reset to 0.1 for kitd=0, below

...

- #ifndef CESMCOUPLED
-             hi_min = p1    ! minimum ice thickness allowed (m) for thermo
- #endif

The following clashes between our branch and main occur in parts of icepack_itd.F90:

<<<<<<< HEAD
=======
#ifndef CESMCOUPLED
            hi_min = p1    ! minimum ice thickness allowed (m) for thermo
#endif
            hi_min =  p2
>>>>>>> c1e1d5d (increase ice and snow thickness minimum values to match CM2, revert conductive flux limits to CM2)

<<<<<<< HEAD
=======
      hi_min = p2    ! minimum ice thickness allowed (m) for thermo
                      ! note hi_min is reset to 0.1 for kitd=0, below

>>>>>>> e4815a4 (Swap hi_min to 0.2 and add aicenmin=1.e-5)

<<<<<<< HEAD
=======
#ifndef CESMCOUPLED
            hi_min = p1    ! minimum ice thickness allowed (m) for thermo
#endif
>>>>>>> e4815a4 (Swap hi_min to 0.2 and add aicenmin=1.e-5)

I think it makes sense for us to pick up the changes from main. Since our CM3 coupling requires hi_min=p1 to match the value in the UM, we need to be careful when bringing in this change.

I've changed the new default value of hi_min in icepack_parameters.F90 from p01 be p1 (required to match UM value), and will add a comment in the namelist warning that hi_min=p1 is required for CM3's coupling.

More straightforward clashes:

Details

In `icepack_therm_bl99.F90`:

<<<<<<< HEAD
      do k = 1, nilyr

         Iswabs_tmp = c0 ! all Iswabs is moved into fswsfc
         if (Tin_init(k) <= Tmlts(k) - sw_dtemp) then
            if (l_brine) then
               ci = cp_ice - Lfresh * Tmlts(k) / (Tin_init(k)**2)
               Iswabs_tmp = min(Iswabs(k), &
                                sw_frac*(Tmlts(k)-Tin_init(k))*ci/dt_rhoi_hlyr)
            else
               ci = cp_ice
               Iswabs_tmp = min(Iswabs(k), &
                                sw_frac*(-Tin_init(k))*ci/dt_rhoi_hlyr)
=======
         do k = 1, nilyr

            Iswabs_tmp = c0 ! all Iswabs is moved into fswsfc
            if (Tin_init(k) <= Tmlts(k) - sw_dtemp) then
               if (l_brine) then
                  ci = cp_ice - Lfresh * Tmlts(k) / (Tin_init(k)**2)
                  Iswabs_tmp = min(Iswabs(k), &
                                 sw_frac*(Tmlts(k)-Tin_init(k))*ci/dt_rhoi_hlyr)
               else
                  ci = cp_ice
                  Iswabs_tmp = min(Iswabs(k), &
                                 sw_frac*(-Tin_init(k))*ci/dt_rhoi_hlyr)
               endif
>>>>>>> b40315a (logging, tweaked newton solver tolerances, re-add einex)

This is an indentation change in our cm3-coupling branch, added to fix the indentation under if calc_Tsfc. Keep changes from cm3-coupling.

<<<<<<< HEAD

               call get_matrix_elements_know_Tsfc (          &
=======
               fcondtopn_force = fcondtopn - fcondtopn_reduction
               call get_matrix_elements_know_Tsfc (nilyr, nslyr, &
>>>>>>> b40315a (logging, tweaked newton solver tolerances, re-add einex)

05ac0ec on main removed the nilyr and nslyr arguments to this subroutine, as they are already available from

use icepack_tracers, only: nilyr, nslyr

at the top of the module. Combine the changes from both branches resulting in:

               fcondtopn_force = fcondtopn - fcondtopn_reduction
               call get_matrix_elements_know_Tsfc (          &

icepack_therm_vertical.F90

<<<<<<< HEAD

      subroutine thermo_vertical (dt,          aicen,     &
=======
      subroutine thermo_vertical (nilyr,       nslyr,     &
                                  dt,          aicen,     &
>>>>>>> b40315a (logging, tweaked newton solver tolerances, re-add einex)

Use changes from main, which remove redundant subroutine arguments.

<<<<<<< HEAD
      massice(:) = c0
      massliq(:) = c0
=======
      e_num = c0
      fcondtopn_extra = c0
>>>>>>> b40315a (logging, tweaked newton solver tolerances, re-add einex)

Separate variable initialisations were added in each branch. Use both changes

      call thickness_changes(dt,          yday,      &
                             efinal,                 &
                             hin,         hilyr,     &
                             hsn,         hslyr,     &
                             zqin,        zqsn,      &
                             smice,       massice,   &
                             smliq,       massliq,   &
                             fbot,        Tbot,      &
                             flatn,       fsurfn,    &
                             fcondtopn_solve,   fcondbotn, &
                             fsnow,       hsn_new,   &
                             fhocnn,      evapn,     &
                             evapsn,      evapin,    &
                             meltt,       melts,     &
                             meltsliq,    frain,     &
                             meltb,                  &
                             congel,      snoice,    &
                             mlt_onset,   frz_onset, &
                             zSin,        sss,       &
<<<<<<< HEAD
                             sst,                    &
                             dsnow,       rsnw)
=======
                             dsnow,       rsnw,       &
                             e_num, fcondtopn_extra   )
>>>>>>> b40315a (logging, tweaked newton solver tolerances, re-add einex)

sst added as argument in main in 4c87095 to allow for one-step congelation formulation. e_num, fcondtopn_extra added in cm3-coupling. Combine both changes into

                             sst,                    &
                             dsnow,       rsnw,      &
                             e_num, fcondtopn_extra  )

Same changes added further down in subroutine definition.

icepack_itd.F90

<<<<<<< HEAD
      use icepack_parameters, only: c0, c1, c2, c3, c15, c25, c100, p1, p01, p001, p5, puny
      use icepack_parameters, only: Lfresh, rhos, ice_ref_salinity, hs_min, cp_ice, rhoi
      use icepack_parameters, only: rhosi, sk_l, hs_ssl, min_salin, rsnw_fall, rhosnew
      use icepack_tracers,    only: ncat, nilyr, nslyr, nblyr, ntrcr, nbtrcr, n_aero
=======
      use icepack_parameters, only: c0, c1, c2, c3, c15, c25, c100, p1, p01, p001, p5, puny, p2
      use icepack_parameters, only: Lfresh, rhos, ice_ref_salinity, hs_min, cp_ice, Tocnfrz, rhoi
      use icepack_parameters, only: rhosi, sk_l, hs_ssl, min_salin, rsnw_fall
>>>>>>> c1e1d5d (increase ice and snow thickness minimum values to match CM2, revert conductive flux limits to CM2)

cm3-coupling adds p2 for use as a minimum ice-thickness. 8fad768 on main removes Tocnfrz, replacing it with Tf (provided as an input from CICE). Main adds rhosnew. 05ac0ec on main adds the line

use icepack_tracers,    only: ncat, nilyr, nslyr, nblyr, ntrcr, nbtrcr, n_aero

and removes these parameters from subroutine arguments.

Keep the changes from both branches, i.e:

      use icepack_parameters, only: c0, c1, c2, c3, c15, c25, c100, p1, p01, p001, p5, puny, p2
      use icepack_parameters, only: Lfresh, rhos, ice_ref_salinity, hs_min, cp_ice, rhoi
      use icepack_parameters, only: rhosi, sk_l, hs_ssl, min_salin, rsnw_fall, rhosnew
      use icepack_tracers,    only: ncat, nilyr, nslyr, nblyr, ntrcr, nbtrcr, n_aero

Additional changes required after resolving merge conflicts

Some additional small changes were needed to get the model to build and run:

Details

Deprecated zsalinity

f5e093f on main deprecated zsalinity.

One solve_zsal flag remained after the rebase due to an indentation change in b40315a, causing the build to fail.

         if (solve_zsal) sw_dtemp = p1  ! lower tolerance with dynamic salinity

This line should be removed to match the changes in main

…onductive flux limits to CM2

…isse

kieranricardo

Looks good to me! Only suggestion is to delete some of the old comments to clean up the diff a little

kieranricardo · 2025-04-23T06:53:23Z

columnphysics/icepack_itd.F90


      use icepack_kinds
-      use icepack_parameters, only: c0, c1, c2, c3, c15, c25, c100, p1, p01, p001, p5, puny
+      use icepack_parameters, only: c0, c1, c2, c3, c15, c25, c100, p1, p01, p001, p5, puny, p2


Do we use p2 here?

Great point. p2 shouldn't be needed here anymore. I've removed it in 33bbca5

columnphysics/icepack_therm_bl99.F90

kieranricardo · 2025-04-23T06:55:16Z

columnphysics/icepack_therm_bl99.F90

            ! Flux extra energy out of the ice
-            fcondbot = fcondbot + einex/dt
+            ! fcondbot = fcondbot + einex/dt



Can delete these commented lines

Removed in 33bbca5!

columnphysics/icepack_therm_vertical.F90

Co-authored-by: Kieran Ricardo <u5824685@anu.edu.au>

kieranricardo and others added 17 commits March 31, 2025 21:48

logging, tweaked newton solver tolerances, re-add einex

0b5be47

extra logging

03d5235

fix argument ordering in set_sfcflux

80dc402

remove cm2 style conductive flux limiting

3d50087

use cm2 style conductive flux limiting

1b539cf

change flux energy error threshold, and reduce fsurf before thermo solve

4d4c7b1

don't reduce fsurf before thermo solve - has no effect

862c39c

convert GBM ice fluxes to local

8f336c5

remove scaling by inverse ice fraction

ca72f1b

reduce fcondtop limiting threshold

e6419ab

increase ice and snow thickness minimum values to match CM2, revert c…

a2d88f3

…onductive flux limits to CM2

scale ice fluxes by changing ice area

0a4650f

more agressively zap small ice areas

9d7ef62

revert zapping back to original values - possible water conservation …

d5296fe

…isse

Swap hi_min to 0.2 and add aicenmin=1.e-5

5cb072d

Remove stray deprecated zsal flag

0cfa7fd

Change default hi_min to p1

31305ce

blimlim mentioned this pull request Apr 17, 2025

Cm3 update cice ACCESS-NRI/CICE#20

Draft

blimlim requested a review from kieranricardo April 21, 2025 23:34

kieranricardo approved these changes Apr 23, 2025

View reviewed changes

kieranricardo changed the base branch from main to cm3-coupling April 23, 2025 07:02

kieranricardo changed the base branch from cm3-coupling to main April 23, 2025 07:06

blimlim and others added 2 commits April 24, 2025 09:43

Remove unnecessary comments

05e415d

Co-authored-by: Kieran Ricardo <u5824685@anu.edu.au>

Review suggestions: remove unnecessary include and comment

33bbca5

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PR for updating icepack to version from OM3-0.4.0 (DO NOT MERGE)#7

PR for updating icepack to version from OM3-0.4.0 (DO NOT MERGE)#7
blimlim wants to merge 19 commits intomainfrom
update-cm3-icepack

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blimlim commented Apr 16, 2025

Not to be merged

Conflicts

Clashes more likely to need review

Change of hi_min parameter

More straightforward clashes:

icepack_therm_vertical.F90

icepack_itd.F90

Additional changes required after resolving merge conflicts

Deprecated zsalinity

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Change of `hi_min` parameter