Define draft dependence function for basal melt adjustment

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

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

@@ -629,10 +629,16 @@ end subroutine li_basal_melt_floating_ice
 !
 !  !  routine calculate_aislens_melt_variability_adjustment
 !
-!> \brief Calculate ice shelf melt rate from depth param.
+!> \brief Calculate the draft dependent ice shelf melt rate component
+!         from the draft params.
 !> \author Shivaprakash Muruganandham
 !> \date   February 2024
-!> \details
+!> \details A melt rate parameterization with a linear melt rate - draft
+!          relationship. In the variability ensemble generator workflow,
+!          this adjustment is the F_d(x_0) term in Eqn 1, from 
+!          Muruganandham, S., Robel, A. A., Hoffman, M. J., & Price, S. (2023).
+!          Statistical Generation of Ocean Forcing With Spatiotemporal Variability for Ice Sheet Models. 
+!          Computing in Science & Engineering.
 !>
 !-----------------------------------------------------------------------
 
@@ -671,20 +677,37 @@ subroutine calculate_aislens_melt_variability_adjustment( &
       !-----------------------------------------------------------------
       ! local variables
       !-----------------------------------------------------------------
-      !real (kind=RKIND) :: slopeSer  ! slope of relation between depth and melt rate
-      !real (kind=RKIND) :: interceptSer  ! depth at which melting goes to 0
+
+      ! slopeSer and interceptSer variables: should they be defined as
+      ! input or local variables for this subroutine?
+
+      real (kind=RKIND) :: slopeSer  ! slope of relation between depth and melt rate
+      real (kind=RKIND) :: interceptSer  ! depth at which melting goes to 0
       !real (kind=RKIND) :: maxMeltSer  ! maximum allowable melt rate
       !real (kind=RKIND) :: sillDepth  ! depth below which melt rate no longer increases
       !real (kind=RKIND), pointer :: config_basal_mass_bal_seroussi_amplitude
       !real (kind=RKIND), pointer :: config_basal_mass_bal_seroussi_period
       !real (kind=RKIND), pointer :: config_basal_mass_bal_seroussi_phase
       !real(kind=RKIND) :: hCavity               ! depth of ice cavity beneath floating ice (m)
-      !real(kind=RKIND) :: zDraft                ! draft of floating ice (m below sea level)
+      real(kind=RKIND) :: zDraft                ! draft of floating ice (m below sea level)
       !integer :: iCell
 
 
       err = 0
+      
+      !Input field values for slopeSer(iCell) and interceptSer(iCell)
+      !from file
 
+
+      do iCell = 1, nCellsSolve
+          zDraft(iCell) = lowerSurface(iCell) - config_sea_level
+          floatingBasalMassBalAdjustment(iCell) = interceptSer(iCell) + &
+                                                  zDraft(iCell) * slopeSer(iCell)
+      enddo ! iCell
+        
+      ! Optional if below is required within subroutine:
+      ! floatingBasalMassBalAdjustment(:) = floatingBasalMassBalAdjustment(:) * config_ice_density / scyr
+      
       !call mpas_pool_get_config(liConfigs, 'config_basal_mass_bal_seroussi_amplitude', &
       !   config_basal_mass_bal_seroussi_amplitude) ! meters
       !call mpas_pool_get_config(liConfigs, 'config_basal_mass_bal_seroussi_period', &
@@ -702,6 +725,7 @@ subroutine calculate_aislens_melt_variability_adjustment( &
       !   err = ior(err, 1)
       !endif
 
+      
       ! Modify intercept height for variability parameters
       !interceptSer = interceptSer + config_basal_mass_bal_seroussi_amplitude * &
       !        sin( (2.0_RKIND * pii / config_basal_mass_bal_seroussi_period) * (daysSinceStart/365.0_RKIND) &