[MITgcm-support] SEAICE, very thick ice

Mon May 18 11:38:36 EDT 2020

Hello everyone!

I get very thick sea ice at several locations in the high-res Kara Sea
model domain (horizontal resolution is 500-1200 m). Interestingly, the
general pattern of sea ice concentration and thickness is OK compared to
MERCATOR ocean reanalysis, but in some regions the modeled HEFF is reported
by the monitor to be about 15 m after 5 months of integration (starting
from realistic initial conditions). I have attached the figure to clarify
what I mean and where it happens.

I suspect the ridging process near the open boundaries to be involved in
this situation, but I do not know what can be done with it.

Such HEFF also produce problems in vertical layers when
useRealFreshWaterFlux is TRUE, but I checked that such too thick ice is
also produced when useRealFreshWaterFlux is OFF, so it is not a cause (at
least, not the main cause).

Unfortunately, there exist too many options to just iterate through all of
them.

May be you can advise what can be done to mitigate such overestimated HEFF?
My preliminary suggestions are as follows, but I am not sure about them:

- to switch off the uice and vice at the OBCS?

- to set SEAICE_no_slip=TRUE to reduce the sea ice velocities near the
coasts to prevent enhanced ridging?

- to use sponge at the open boundaries?

- there was a CPP key OBCS_SEAICE_AVOID_CONVERGENCE, but it is only for
OBCS_UVICE_OLD which, in turn, is undefined by default and even may be not
implemented, as stated.

Any advice is very welcome!

Stanislav

PS: I use a SEAICE package configuration which is very close to the default
one. What I have changed is:

#define SEAICE_VARIABLE_SALINITY

SEAICEadvScheme = 33,

SEAICE_multDim = 1,
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C     *==========================================================*
C     | SEAICE_OPTIONS.h
C     | o CPP options file for sea ice package.
C     *==========================================================*
C     | Use this file for selecting options within the sea ice
C     | package.
C     *==========================================================*

#ifndef SEAICE_OPTIONS_H
#define SEAICE_OPTIONS_H
#include "PACKAGES_CONFIG.h"
#include "CPP_OPTIONS.h"

#ifdef ALLOW_SEAICE
C     Package-specific Options & Macros go here

C--   Write "text-plots" of certain fields in STDOUT for debugging.
#undef SEAICE_DEBUG

C--   Allow sea-ice dynamic code.
C     This option is provided to allow use of TAMC
C     on the thermodynamics component of the code only.
C     Sea-ice dynamics can also be turned off at runtime
C     using variable SEAICEuseDYNAMICS.
#define SEAICE_ALLOW_DYNAMICS

C--   By default, the sea-ice package uses its own integrated bulk
C     formulae to compute fluxes (fu, fv, EmPmR, Qnet, and Qsw) over
C     open-ocean.  When this flag is set, these variables are computed
C     in a separate external package, for example, pkg/exf, and then
C     modified for sea-ice effects by pkg/seaice.
#define SEAICE_EXTERNAL_FLUXES

C--   This CPP flag has been retired.  The number of ice categories
C     used to solve for seaice flux is now specified by run-time
C     parameter SEAICE_multDim.
C     Note: be aware of pickup_seaice.* compatibility issues when
C     restarting a simulation with a different number of categories.
c#define SEAICE_MULTICATEGORY

C--   run with sea Ice Thickness Distribution (ITD);
C     set number of categories (nITD) in SEAICE_SIZE.h
#undef SEAICE_ITD

C--   Since the missing sublimation term is now included
C     this flag is needed for backward compatibility
#undef SEAICE_DISABLE_SUBLIM

C--   Suspected missing term in coupled ocn-ice heat budget (to be confirmed)
#undef SEAICE_DISABLE_HEATCONSFIX

C--   Default is constant seaice salinity (SEAICE_salt0); Define the following
C     flag to consider (space & time) variable salinity: advected and forming
C     seaice with a fraction (=SEAICE_saltFrac) of freezing seawater salinity.
C- Note: SItracer also offers an alternative way to handle variable salinity.
#define SEAICE_VARIABLE_SALINITY

C--   Tracers of ice and/or ice cover.
#undef ALLOW_SITRACER
#ifdef ALLOW_SITRACER
C--   To try avoid 'spontaneous generation' of tracer maxima by advdiff.
# define ALLOW_SITRACER_ADVCAP
#endif

C--   Enable grease ice parameterization
C     The grease ice parameterization delays formation of solid
C     sea ice from frazil ice by a time constant and provides a
C     dynamic calculation of the initial solid sea ice thickness
C     HO as a function of winds, currents and available grease ice
C     volume. Grease ice does not significantly reduce heat loss
C     from the ocean in winter and area covered by grease is thus
C     handled like open water.
C     (For details see Smedsrud and Martin, 2014, Ann.Glac.)
C     Set SItrName(1) = 'grease' in namelist SEAICE_PARM03 in data.seaice
C     then output SItr01 is SItrNameLong(1) = 'grease ice volume fraction',
C     with SItrUnit(1) = '[0-1]', which needs to be multiplied by SIheff
C     to yield grease ice volume. Additionally, the actual grease ice
C     layer thickness (diagnostic SIgrsLT) can be saved.
#undef SEAICE_GREASE
C--   grease ice uses SItracer:
#ifdef SEAICE_GREASE
# define ALLOW_SITRACER
# define ALLOW_SITRACER_ADVCAP
#endif

C--   Historically, the seaice model was discretized on a B-Grid. This
C     discretization should still work but it is not longer actively tested
C     and supported. The following flag should always be set in order to use
C     the operational C-grid discretization.
#define SEAICE_CGRID

C--   Only for the C-grid version it is possible to
#ifdef SEAICE_CGRID
C     enable advection of sea ice momentum
# undef SEAICE_ALLOW_MOM_ADVECTION
C     enable JFNK code by defining the following flag
# define SEAICE_ALLOW_JFNK
C     enable Krylov code by defining the following flag
# define SEAICE_ALLOW_KRYLOV
C     enable LSR to use global (multi-tile) tri-diagonal solver
# undef SEAICE_GLOBAL_3DIAG_SOLVER
C     enable EVP code by defining the following flag
# define SEAICE_ALLOW_EVP
# ifdef SEAICE_ALLOW_EVP
C--   When set use SEAICE_zetaMin and SEAICE_evpDampC to limit viscosities
C     from below and above in seaice_evp: not necessary, and not recommended
#  undef SEAICE_ALLOW_CLIPZETA
# endif /* SEAICE_ALLOW_EVP */
C     smooth regularization (without max-function) of delta for
C     better differentiability
# undef SEAICE_DELTA_SMOOTHREG
C     regularize zeta to zmax with a smooth tanh-function instead
C     of a min(zeta,zmax). This improves convergence of iterative
C     solvers (Lemieux and Tremblay 2009, JGR). No effect on EVP
# define SEAICE_ZETA_SMOOTHREG
C     allow the truncated ellipse rheology (runtime flag SEAICEuseTEM)
# undef SEAICE_ALLOW_TEM
C     Use LSR vector code; not useful on non-vector machines, because it
C     slows down convergence considerably, but the extra iterations are
C     more than made up by the much faster code on vector machines. For
C     the only regularly test vector machine these flags a specified
C     in the build options file SUPER-UX_SX-8_sxf90_awi, so that we comment
C     them out here.
# undef SEAICE_VECTORIZE_LSR
C     Use zebra-method (alternate lines) for line-successive-relaxation
C     This modification improves the convergence of the vector code
C     dramatically, so that is may actually be useful in general, but
C     that needs to be tested. Can be used without vectorization options.
# undef SEAICE_LSR_ZEBRA
C     Use parameterisation of grounding ice for a better representation
C     of fastice in shallow seas
# undef SEAICE_ALLOW_BOTTOMDRAG
#else /* not SEAICE_CGRID, but old B-grid */
C--   By default for B-grid dynamics solver wind stress under sea-ice is
C     set to the same value as it would be if there was no sea-ice.
C     Define following CPP flag for B-grid ice-ocean stress coupling.
# define SEAICE_BICE_STRESS

C--   By default for B-grid dynamics solver surface tilt is obtained
C     indirectly via geostrophic velocities. Define following CPP
C     in order to use ETAN instead.
# define EXPLICIT_SSH_SLOPE
C--   Defining this flag turns on FV-discretization of the B-grid LSOR solver.
C     It is smoother and includes all metric terms, similar to C-grid solvers.
C     It is here for completeness, but its usefulness is unclear.
# undef SEAICE_LSRBNEW
#endif /* SEAICE_CGRID */

C--   When set limit the Ice-Loading to mass of 1/5 of Surface ocean grid-box
#undef SEAICE_CAP_ICELOAD
C--   When set use SEAICE_clipVelocties = .true., to clip U/VICE at 40cm/s,
C     not recommended
#undef SEAICE_ALLOW_CLIPVELS
C--   When set cap the sublimation latent heat flux in solve4temp according
C     to the available amount of ice+snow. Otherwise this term is treated
C     like all of the others -- residuals heat and fw stocks are passed to
C     the ocean at the end of seaice_growth in a conservative manner.
C     SEAICE_CAP_SUBLIM is not needed as of now, but kept just in case.
#undef SEAICE_CAP_SUBLIM

C--   Enable the adjointable sea-ice thermodynamic model
C     uses seaice_growth_adx.F and seaice_solve4temp_adx.F
#undef ALLOW_SEAICE_GROWTH_ADX

C--   Enable free drift code
#undef SEAICE_ALLOW_FREEDRIFT

C--   pkg/seaice cost functions compile flags
c       >>> Sea-ice volume (requires pkg/cost)
#undef ALLOW_COST_ICE
c       >>> Sea-ice misfit to obs (requires pkg/cost and ecco)
#undef ALLOW_SEAICE_COST_SMR_AREA

#endif /* ALLOW_SEAICE */
#endif /* SEAICE_OPTIONS_H */

CEH3 ;;; Local Variables: ***
CEH3 ;;; mode:fortran ***
CEH3 ;;; End: ***
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#ifndef CPP_OPTIONS_H
#define CPP_OPTIONS_H

CBOP
C !ROUTINE: CPP_OPTIONS.h
C !INTERFACE:
C #include "CPP_OPTIONS.h"

C !DESCRIPTION:
C *==================================================================*
C | main CPP options file for the model:
C | Control which optional features to compile in model/src code.
C *==================================================================*
CEOP

C CPP flags controlling particular source code features

C-- Forcing code options:

C o Shortwave heating as extra term in external_forcing.F
C Note: this should be a run-time option
#define SHORTWAVE_HEATING

C o Include/exclude Geothermal Heat Flux at the bottom of the ocean
#undef ALLOW_GEOTHERMAL_FLUX

C o Allow to account for heating due to friction (and momentum dissipation)
#undef ALLOW_FRICTION_HEATING

C o Allow mass source or sink of Fluid in the interior
C   (3-D generalisation of oceanic real-fresh water flux)
#undef ALLOW_ADDFLUID

C o Include pressure loading code
#define ATMOSPHERIC_LOADING

C o Include/exclude balancing surface forcing fluxes code
#undef ALLOW_BALANCE_FLUXES

C o Include/exclude balancing surface forcing relaxation code
#undef ALLOW_BALANCE_RELAX

C o Include/exclude checking for negative salinity
#define CHECK_SALINITY_FOR_NEGATIVE_VALUES

C-- Options to discard parts of the main code:

C o Exclude/allow external forcing-fields load
C   this allows to read & do simple linear time interpolation of oceanic
C   forcing fields, if no specific pkg (e.g., EXF) is used to compute them.
#undef EXCLUDE_FFIELDS_LOAD

C o Include/exclude phi_hyd calculation code
#define INCLUDE_PHIHYD_CALCULATION_CODE

C-- Vertical mixing code options:

C o Include/exclude call to S/R CONVECT
#define INCLUDE_CONVECT_CALL

C o Include/exclude call to S/R CALC_DIFFUSIVITY
#define INCLUDE_CALC_DIFFUSIVITY_CALL

C o Allow full 3D specification of vertical diffusivity
#undef ALLOW_3D_DIFFKR

C o Allow latitudinally varying BryanLewis79 vertical diffusivity
#undef ALLOW_BL79_LAT_VARY

C o Exclude/allow partial-cell effect (physical or enhanced) in vertical mixing
C   this allows to account for partial-cell in vertical viscosity and diffusion,
C   either from grid-spacing reduction effect or as artificially enhanced mixing
C   near surface & bottom for too thin grid-cell
#undef EXCLUDE_PCELL_MIX_CODE

C-- Time-stepping code options:

C o Include/exclude combined Surf.Pressure and Drag Implicit solver code
#undef ALLOW_SOLVE4_PS_AND_DRAG

C o Include/exclude Implicit vertical advection code
#define INCLUDE_IMPLVERTADV_CODE

C o Include/exclude AdamsBashforth-3rd-Order code
#undef ALLOW_ADAMSBASHFORTH_3

C-- Model formulation options:

C o Allow/exclude "Exact Convervation" of fluid in Free-Surface formulation
C   that ensures that d/dt(eta) is exactly equal to - Div.Transport
#define EXACT_CONSERV

C o Allow the use of Non-Linear Free-Surface formulation
C   this implies that grid-cell thickness (hFactors) varies with time
#define NONLIN_FRSURF
C#undef NONLIN_FRSURF

C o Include/exclude nonHydrostatic code
#undef ALLOW_NONHYDROSTATIC

C o Include/exclude GM-like eddy stress in momentum code
#undef ALLOW_EDDYPSI

C-- Algorithm options:

C o Use Non Self-Adjoint (NSA) conjugate-gradient solver
#undef ALLOW_CG2D_NSA

C o Include/exclude code for single reduction Conjugate-Gradient solver
#define ALLOW_SRCG

C o Choices for implicit solver routines solve_*diagonal.F
C   The following has low memory footprint, but not suitable for AD
#undef SOLVE_DIAGONAL_LOWMEMORY
C   The following one suitable for AD but does not vectorize
#undef SOLVE_DIAGONAL_KINNER

C-- Retired code options:

C o ALLOW isotropic scaling of harmonic and bi-harmonic terms when
C   using an locally isotropic spherical grid with (dlambda) x (dphi*cos(phi))
C *only for use on a lat-lon grid*
C   Setting this flag here affects both momentum and tracer equation unless
C   it is set/unset again in other header fields (e.g., GAD_OPTIONS.h).
C   The definition of the flag is commented to avoid interference with
C   such other header files.
C   The preferred method is specifying a value for viscAhGrid or viscA4Grid
C   in data which is then automatically scaled by the grid size;
C   the old method of specifying viscAh/viscA4 and this flag is provided
C   for completeness only (and for use with the adjoint).
C#define ISOTROPIC_COS_SCALING

C o This flag selects the form of COSINE(lat) scaling of bi-harmonic term.
C *only for use on a lat-lon grid*
C   Has no effect if ISOTROPIC_COS_SCALING is undefined.
C   Has no effect on vector invariant momentum equations.
C   Setting this flag here affects both momentum and tracer equation unless
C   it is set/unset again in other header fields (e.g., GAD_OPTIONS.h).
C   The definition of the flag is commented to avoid interference with
C   such other header files.
C#define COSINEMETH_III

C o Use "OLD" UV discretisation near boundaries (*not* recommended)
C   Note - only works with pkg/mom_fluxform and "no_slip_sides=.FALSE."
C          because the old code did not have no-slip BCs
#undef OLD_ADV_BCS

C o Use LONG.bin, LATG.bin, etc., initialization for ini_curviliear_grid.F
C   Default is to use "new" grid files (OLD_GRID_IO undef) but OLD_GRID_IO
C   is still useful with, e.g., single-domain curvilinear configurations.
#define OLD_GRID_IO

C o Use thsice+seaice (old) call sequence: ice-Dyn,ice-Advect,ice-Thermo(thsice)
C              as opposed to new sequence: ice-Thermo(thsice),ice-Dyn,ice-Advect
#undef OLD_THSICE_CALL_SEQUENCE

C o Use old EXTERNAL_FORCING_U,V,T,S subroutines (for backward compatibility)
#undef USE_OLD_EXTERNAL_FORCING

C-- Other option files:

C o Execution environment support options
#include "CPP_EEOPTIONS.h"

C o Include/exclude single header file containing multiple packages options
C   (AUTODIFF, COST, CTRL, ECCO, EXF ...) instead of the standard way where
C   each of the above pkg get its own options from its specific option file.
C   Although this method, inherited from ECCO setup, has been traditionally
C   used for all adjoint built, work is in progress to allow to use the
C   standard method also for adjoint built.
c#ifdef PACKAGES_CONFIG_H
c# include "ECCO_CPPOPTIONS.h"
c#endif

#endif /* CPP_OPTIONS_H */
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C CPP options file for OBCS package
C Use this file for selecting options within the OBCS package

#ifndef OBCS_OPTIONS_H
#define OBCS_OPTIONS_H
#include "PACKAGES_CONFIG.h"
#include "CPP_OPTIONS.h"

#ifdef ALLOW_OBCS
C Package-specific Options & Macros go here

C Enable individual open boundaries
#define ALLOW_OBCS_NORTH
#undef ALLOW_OBCS_SOUTH
#define ALLOW_OBCS_EAST
#define ALLOW_OBCS_WEST

C This include hooks to the Orlanski Open Boundary Radiation code
#undef ALLOW_ORLANSKI

C Enable OB values to be prescribed via external fields that are read
C from a file
#define ALLOW_OBCS_PRESCRIBE

C Enable OB conditions following Stevens (1990)
#undef ALLOW_OBCS_STEVENS

C Allow sponge layer treatment of open boundary conditions
#define ALLOW_OBCS_SPONGE

C Include hooks to sponge layer treatment of pkg/seaice variables
#define ALLOW_OBCS_SEAICE_SPONGE

C balance barotropic velocity
#define ALLOW_OBCS_BALANCE

C add tidal contributions to normal OB flow
C NOTE that at the moment tidal forcing is applied
C only to "normal" flow.
#undef ALLOW_OBCS_TIDES

C Use older implementation of obcs in seaice-dynamics
C note: most of the "experimental" options listed below have not yet
C       been implementated in new version.
#undef OBCS_UVICE_OLD

#ifdef OBCS_UVICE_OLD
C     The following five CPP options are experimental and aim to deal
C     with artifacts due to the low-frequency specification of sea-ice
C     boundary conditions compared to the model forcing frequency.
C     Ice convergence at edges can cause model to blow up.  The
C     following CPP option fixes this problem at the expense of less
C     accurate boundary conditions.
#undef OBCS_SEAICE_AVOID_CONVERGENCE

C     Smooth the component of sea-ice velocity perpendicular to the edge.
#undef OBCS_SEAICE_SMOOTH_UVICE_PERP

C     Smooth the component of sea ice velocity parallel to the edge.
#undef OBCS_SEAICE_SMOOTH_UVICE_PAR

C     Compute rather than specify seaice velocities at the edges.
#undef OBCS_SEAICE_COMPUTE_UVICE
#endif /* OBCS_UVICE_OLD */

C     Smooth the tracer sea-ice variables near the edges.
#define OBCS_SEAICE_SMOOTH_EDGE

#endif /* ALLOW_OBCS */
#endif /* OBCS_OPTIONS_H */
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