Enable HLM to create multiple columns for the vegetated landunit

[glemieux]

The current model assumes a single column for the vegetated landunit, which is added upon gridcell initliazation:

E3SM/components/elm/src/main/initGridCellsMod.F90

Lines 347 to 348 in 67abd00

	! Assume one column on the landunit
	call add_column(ci=ci, li=li, ctype=1, wtlunit=1.0_r8)

We will need to allow multiple soil columns for a vegetated land unit to be added during initialization such that when we have disturbance of the soil we move the appropriate patches and their area to the appropriate time-since-fire age class bin column. This movement will need to be triggered by a disturbance mechanism similar to what we do with fates.

This will require updating the column weighting for the relevant upstream hierarchical unit:

E3SM/components/elm/src/data_types/ColumnType.F90

Lines 34 to 40 in 67abd00

	! indices and weights for higher subgrid levels (landunit, topounit, gridcell)
	integer , pointer :: gridcell (:) => null() ! index into gridcell level quantities
	real(r8), pointer :: wtgcell (:) => null() ! weight (relative to gridcell)
	integer , pointer :: topounit (:) => null() ! index into topounit level quantities
	real(r8), pointer :: wttopounit (:) => null() ! weight (relative to topounit)
	integer , pointer :: landunit (:) => null() ! index into landunit level quantities
	real(r8), pointer :: wtlunit (:) => null() ! weight (relative to landunit)

Tasks

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1. Add mechanism to trigger column re-weighting based on soil disturbance #3
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2. Update column weighting upon disturbance #4
   0 of 3
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3. Update handling of fates sites area to maintain consistency across fates columns in a given gridcell #6
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4. Update HLM decomposition of columns to make sure that fates columns that are passing patches are colocated on a clump #7
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5. Allow FATES parameter to control the time-since-disturbance host land model column binning #12
   0 of 1
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[glemieux]

Not that currently all calls to add_column take place in initGridCellsMod via different set_landunit_... calls. These are all wrapped up in the initGridCells subroutine:

E3SM/components/elm/src/main/initGridCellsMod.F90

Lines 138 to 140 in 67abd00

	call set_landunit_veg_compete( &
	ltype=istsoil, gi=top_pp%gridcell(topounit), ti=topounit,topo_ind=topo_ind, li=li, ci=ci, pi=pi, &
	setdata=.true.)