Update depth-dependent ice-shelf basal melt parameterization and add variability input field #103

mshiv · 2024-02-07T21:10:27Z

This PR replaces an existing ice shelf basal melt parameterization method and adds a basal melt variability input field, both in support of test cases where MALI is forced directly from the basal melt variable.

Draft-dependent basal melt parameterization method:

The draft_dependence method is introduced to calculate basal melt as a function of ice shelf draft.
It replaces the previously define seroussi method. A key difference is that these coefficients are now expected as user-defined input fields, allowing for spatially varying coefficient values.
In its current form, this is a linear function with two coefficients, draftDepenBasalMeltAlpha0 (intercept parameter) and draftDepenBasalMeltAlpha1 (slope parameter).
These coefficients are presently time-independent, and defined via offline pre-processing (regressing basal melt with draft)
Currently, this method is used when MALI is forced directly using the ice shelf basal melt (floatingBasalMassBal) variable.

Input field for basal melt adjustment:

A new variable floatingBasalMassBalAdjustment is defined, also as a user-defined input field.
When MALI is forced directly by floatingBasalMassBal, this adjustment field can be used to add basal melt forcing components that are not draft dependent. For example: linear trend, seasonality, internal climate variability components.
This can be a spatially and temporally varying 3-dimensional field.

Add Registry and ice shelf melt driver changes to support new calculate_aislens_melt_variability_adjustment subroutine call

Add linear draft-dependent (spatial dependence) basal melt adjustment for AISLENS generator.

Add slopeGen and interceptGen coefficients for the draft dependence

…melt generator Define draft dependence function variables for calculating floatingBasalMassBalAdjustment in aislens basalMassBal adjustment subroutine

Define slopeGen, interceptGen, zDraft variables as part of aislens package

matthewhoffman

@mshiv , thanks for putting this PR together. After looking over it again, I have a few more requests. Also, please update the description of the PR (on the main PR page below the PR title) with a few details:

describe how/why the slope and intercept are fields rather than namelist options
describe the new floatingBasalMassBalAdjustment field, which is not directly related to the depth-dependent melt param.
explain that this new method is replacing the 'seroussi' option

components/mpas-albany-landice/src/Registry.xml

Co-authored-by: Matt Hoffman <wyeast@gmail.com>

Rename interceptGen to draftDepenBasalMeltAlpha0 Rename slopeGen to draftDepenBasalMeltAlpha1 This will allow for easier changes to the functional form used in the draft dependence melt parameterization

Update variables for the basal_melt_draft_dependence subroutine: rename: interceptGen -> draftDepenBasalMeltAlpha0 and slopeGen -> draftDepenBasalMeltAlpha1 Update definitions Add the above variables and floatingBasalMassBalAdjustment to input and restart streams.

components/mpas-albany-landice/src/Registry.xml

trhille · 2024-03-15T20:45:48Z

Is there a configuration that makes this equivalent to config_basal_mass_bal_float = 'seroussi'? We will need to update several COMPASS tests in full_integration that currently use seroussi:

00:11 FAIL landice_thwaites_fo_decomposition_test
00:13 FAIL landice_thwaites_fo_restart_test
00:08 FAIL landice_thwaites_fo-depthInt_decomposition_test
00:07 FAIL landice_thwaites_fo-depthInt_restart_test

All other tests passed validation and baseline comparison.

trhille · 2024-03-15T20:53:11Z

components/mpas-albany-landice/src/Registry.xml

@@ -1224,6 +1220,15 @@ is the value of that variable from the *previous* time level!
                <var name="floatingBasalMassBal" type="real" dimensions="nCells Time" units="kg m^{-2} s^{-1}"
                     description="Potential basal mass balance on floating regions"
                />
+                <var name="floatingBasalMassBalAdjustment" type="real" dimensions="nCells Time" units="kg m^{-2} s^{-1}" default_value="0.0"


It's not clear what the difference is between floatingBasalMassBalAdjustment and draftDepenBasalMeltAlpha0. The descriptions need more detail. For which cases is floatingBasalMassBalAdjustment used?

Technically, they are similar in that they are both added to the product of draft and draftDepenBasalMeltAlpha1. Main difference is that draftDepenBasalMeltAlpha0 (and draftDepenBasalMeltAlpha1) is time independent while floatingBasalMassBalAdjustment can be time dependent, with the latter being read in via a forcing file input stream.

draftDepenBasalMeltAlpha0 and draftDepenBasalMeltAlpha1 are maps derived via a regression of basal melt with draft.

floatingBasalMassBalAdjustment is treated as an optional additional basal melt forcing value - in the context of the AISLENS experiments, it includes time varying basal melt forcing that can have secular/seasonal trends and variability, or a combination of them. Will update the main description above as well.

components/mpas-albany-landice/src/mode_forward/mpas_li_iceshelf_melt.F

trhille · 2024-03-15T21:18:39Z

components/mpas-albany-landice/src/mode_forward/mpas_li_iceshelf_melt.F

         ! Shut off melt at an arbitrary shallow depth to discourage ice from disappearing.
-         if ( (li_mask_is_floating_ice(cellMask(iCell))) .and. (lowerSurface(iCell) < -10.0_RKIND) ) then
+         if ( li_mask_is_floating_ice(cellMask(iCell))) then


To be completely accurate, this should probably treat dynamic and non-dynamic cells differently. Melt rates for non-dynamic cells should probably be calculated using the draft values from neighboring dynamic cells. @matthewhoffman, what do you think?

I think we should probably be doing that, but if we include that, it should probably be done for all melt options. Looks like we sort of say we are doing that at line 586 but it's not actually doing it. Or maybe it should happen where BMB is actually applied, using the dynamic mask that exists at that point. I think that should be a separate PR, given it would change the application of all melt rate methods.

Delete stray comments from previously defined seroussi method Co-authored-by: Trevor Hillebrand <trhille@lanl.gov>

Co-authored-by: Trevor Hillebrand <trhille@lanl.gov>

Update components/mpas-albany-landice/src/mode_forward/mpas_li_iceshelf_melt.F Co-authored-by: Trevor Hillebrand <trhille@lanl.gov>

mshiv · 2024-07-16T15:26:43Z

Is there a configuration that makes this equivalent to config_basal_mass_bal_float = 'seroussi'? We will need to update several COMPASS tests in full_integration that currently use seroussi:
00:11 FAIL landice_thwaites_fo_decomposition_test
00:13 FAIL landice_thwaites_fo_restart_test
00:08 FAIL landice_thwaites_fo-depthInt_decomposition_test
00:07 FAIL landice_thwaites_fo-depthInt_restart_test
All other tests passed validation and baseline comparison.

That might require a rewrite of draft_dependence to include the sillDepth and maxMeltSer parameters defined in seroussi. Would it be worth doing that, @matthewhoffman?

mshiv added the in progress Still being worked on, don't merge yet! label Feb 7, 2024

Shivaprakash Muruganandham and others added 2 commits February 7, 2024 14:56

Add basal melt draft dependence subroutine

07cac84

add driver changes for calculate_aislens_melt_variability_adjustment

cfe4264

Add Registry and ice shelf melt driver changes to support new calculate_aislens_melt_variability_adjustment subroutine call

matthewhoffman force-pushed the mshiv/mali/basal_melt_draft_dependence branch from 76bb23d to cfe4264 Compare February 7, 2024 22:58

mshiv added 6 commits February 15, 2024 08:09

Define draft dependence function for basal melt adjustment

8611707

Add linear draft-dependent (spatial dependence) basal melt adjustment for AISLENS generator.

Update draft dependence function for basalMassBalAdjustment

b64b61b

Add slopeGen and interceptGen coefficients for the draft dependence

Add draft dependent co-efficient variables for the aislens ice shelf …

8f9f6cb

…melt generator Define draft dependence function variables for calculating floatingBasalMassBalAdjustment in aislens basalMassBal adjustment subroutine

Update calculate_aislens_melt_variability_adjustment subroutine

9f124fc

Add aislens namelist and streams variables and package

2dc1067

Define slopeGen, interceptGen, zDraft variables as part of aislens package

Add draft dependence subroutine

bb469c4

mshiv force-pushed the mshiv/mali/basal_melt_draft_dependence branch from 98a86c9 to bb469c4 Compare February 16, 2024 22:24

matthewhoffman added enhancement New feature or request and removed in progress Still being worked on, don't merge yet! labels Feb 17, 2024

matthewhoffman self-assigned this Feb 20, 2024

matthewhoffman changed the title ~~Add basal melt variability emulator~~ Update depth-dependent ice-shelf basal melt parameterization and add variability input field Feb 20, 2024

Update description of draft dependent melt rate subroutine

b9c50e3

matthewhoffman requested changes Feb 28, 2024

View reviewed changes

mshiv and others added 2 commits March 1, 2024 11:37

Update comments for draft dependent parameterization

ec75f7a

Co-authored-by: Matt Hoffman <wyeast@gmail.com>

Update config option description for basal mass balance methods

dce872d

Co-authored-by: Matt Hoffman <wyeast@gmail.com>

trhille unassigned matthewhoffman Mar 1, 2024

trhille self-requested a review March 1, 2024 21:12

mshiv added 4 commits March 8, 2024 07:44

Cleanup comments

9b3cdd0

Rename draft dependent melt parameterization variables

23440c8

Rename interceptGen to draftDepenBasalMeltAlpha0 Rename slopeGen to draftDepenBasalMeltAlpha1 This will allow for easier changes to the functional form used in the draft dependence melt parameterization

Update basal melt config options description

0e3a4fb

matthewhoffman reviewed Mar 8, 2024

View reviewed changes

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matthewhoffman reviewed Mar 8, 2024

View reviewed changes

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matthewhoffman reviewed Mar 8, 2024

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components/mpas-albany-landice/src/Registry.xml Show resolved Hide resolved

Remove package assignment for floatingBasalMassBalAdjustment

f50f131

trhille requested changes Mar 15, 2024

View reviewed changes

mshiv and others added 3 commits March 18, 2024 11:49

Clean up draft_dependence ice shelf basal melt method

b3c1eb0

Delete stray comments from previously defined seroussi method Co-authored-by: Trevor Hillebrand <trhille@lanl.gov>

Clean up draft_dependence ice shelf basal melt method

50abf8d

Co-authored-by: Trevor Hillebrand <trhille@lanl.gov>

Update floatingBasalMassBal calculation for consistent SI units

a84cd6a

Update components/mpas-albany-landice/src/mode_forward/mpas_li_iceshelf_melt.F Co-authored-by: Trevor Hillebrand <trhille@lanl.gov>

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Update depth-dependent ice-shelf basal melt parameterization and add variability input field #103

Update depth-dependent ice-shelf basal melt parameterization and add variability input field #103

mshiv commented Feb 7, 2024 •

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mshiv commented Jul 16, 2024

Update depth-dependent ice-shelf basal melt parameterization and add variability input field #103

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Update depth-dependent ice-shelf basal melt parameterization and add variability input field #103

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