Ice-sheet model SICOPOLIS
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Version history (2.9 and older)
Current version : 2.9
Date : 2008-12-17
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V1.0: Modular version of SICOPOLIS, applicable to any
ice sheet.
-----------------------------------------------------------
Based on sicopolis_nhem.F95 V4.0
(northern-hemisphere version of SICOPOLIS).
-----------------------------------------------------------------
V1.1: Optional new boundary conditions for the ice
surface at the margin of the computational domain
(parameter BC_MARG).
-----------------------------------------------------------------
V1.2: Optional first-order-upstream discretization
of vertical advection terms without artificial
diffusion in the age equation
(parameter ADV_VERT).
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Optional exponential coupling between accumulation
and delta_ts (parameter ACCSURFACE==3).
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V1.3: New module for the southern hemisphere included
(parameter DOMAIN==4).
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Improved reading of ice-core-temperature and
sea-level data, no longer restricted to the
interval from 250 kyr BP to today.
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New model domain for Scandinavia included
(parameter DOMAIN==2).
-----------------------------------------------------------------
V1.4: New module for Antarctica included.
-----------------------------------------------------------
Bugfix in subroutines sico_init
(for grl, shem, nmars):
Parameter list in calls of subroutine boundary
for parameter ANF_DAT==3 corrected.
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Mars module: Degree-day model replaced by simpler
accumulation-ablation parameterization.
-----------------------------------------------------------------
V2.0: All file extensions changed from '.F95' to '.F90'.
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COMMON blocks in input file 'sico.common' replaced
by module 'sico_variables'.
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Character variable 'runname' (name of current run)
can have an arbitrary length of less than
100 characters.
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Variables d_help_c, d_help_t, h_diff,
maske, maske_help, n_cts, n_cts_neu, kc_cts,
as_perp, temp_s
now declared globally in module 'sico_variables'.
-----------------------------------------------------------
The header file 'sicoheader.F95' does no longer
exist; however, 'sicopolis.F90' is compiled
directly.
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Header file with simulation specifications must
be called 'sico_specs.h'.
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Explicit definition of paths INPATH (for input
files), OUTPATH (for output files), ANFDATPATH
(for initial-value file) and Z_SLE_PATH (for
previously computed time-series file with
sea-level equivalents) in specifications file.
-----------------------------------------------------------
Parameter DOMAIN removed. Instead, the
computational domain is now defined by a macro
ANT, GRL, SCAND, NHEM, SHEM, EMTP2SGE or NMARS.
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Parameter BC_MARG (see version 1.1) removed, back
to zero-thickness boundary condition at the margin
of the numerical domain as the only possibility.
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Geothermal heat flux (Q_GEO), flow-enhancement factor
(ENH) and minimum ice thickness interpreted as glaciation
(H_MIN) now defined in header file sico_specs.h.
-----------------------------------------------------------
Physical parameters now read from a file by the
new subroutine 'phys_para'.
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Indexing of arrays RF(T), KAPPA(T) and C(T)
changed such that the index T now corresponds to
the temperature in deg C.
-----------------------------------------------------------
Computation of the horizontal mass flux qx, qy
moved from subroutine 'calc_top' to subroutine
'calc_vxy'.
-----------------------------------------------------------
Forcing quantities delta_ts and z_sl added to
the output for the time-slice files produced by
subroutine 'output1'.
-----------------------------------------------------------
Bugfix in subroutine 'calc_top':
In the diffusive smoothing scheme for zs_neu, the
denominator of the correction factor 'korrfakt'
can no longer become zero due to the insertion
of a volume offset eps_vol.
-----------------------------------------------------------------
V2.0.1: Maximum surface velocity now written to the time-series
files.
-----------------------------------------------------------------
V2.0.2: Module for the southern hemisphere deleted.
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New Greenland topography data based on Letreguilly and
ETOPO5 with slightly smoothed relaxed bedrock used.
-----------------------------------------------------------------
V2.0.3: Limitation of the computed horizontal velocities to an
interval [-VH_MAX, VH_MAX] to be prescribed in the
header file.
-----------------------------------------------------------------
V2.0.4: Implementation of alternative flow laws
(Goldsby-Kohlstedt, Durham) in addition to the usual
Glen's flow law (parameter FLOW_LAW).
---------------------------------------------------------
For the north polar cap of Mars, the average dust content
of the ice can be specified (parameter FRAC_DUST).
-----------------------------------------------------------------
V2.1: Spatially variable geothermal heat flux implemented, can
be chosen by new parameter Q_GEO_MOD.
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Output of time-series file for ice-core locations
prescribed in subroutine sico_init implemented
(parameter OUTSER==3).
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New module for the south-polar cap of Mars included
(macro SMARS).
-----------------------------------------------------------
For the Martian ice caps (NMARS, SMARS), the mass balance
is now converted from water equiv. to (ice+dust) equiv.
(previously the dust was ignored).
-----------------------------------------------------------------
V2.2: Sub-melt basal sliding implemented (parameter GAMMA_SLIDE
in phys_para file; 0: no sub-melt sliding).
-----------------------------------------------------------
Greenland:
- New Bamber topography implemented, horizontal resolution
40, 20 or 10 km.
- Surface temperatures (mean annual, mean July)
parameterised by Ritz et al. (1997).
- Precipitation instead of solid accumulation used as
input.
- Reeh's degree day model with statistical fluctuations,
supplemented by explicit consideration of rainfall
and different ice/snow degree-day factors for warm
and cold conditions (parameters BETA1_LT_0, BETA1_HT_0,
BETA2_LT_0, BETA2_HT_0 in phys_para file).
- Net surface mass balance computed as precipitation minus
runoff (previously solid accumulation minus melting).
- Optional climate forcing by glacial index and prescribed
LGM anomalies for surface temperature and precipitation
(parameters TSURFACE==5 and ACCSURFACE==5).
-----------------------------------------------------------
Martian ice caps (NMARS, SMARS):
- Accumulation input either in water equiv.
or in (ice+dust) equiv. (parameter ACC_UNIT).
- Lower limit of -125/-128 deg C (sublimation temperature
of CO2 over the NPC/SPC) introduced for the ice surface
temperature.
-----------------------------------------------------------------
V2.3: Implementation of Bjoern Grieger's surface-temperature
parameterisation for the Martian ice caps (parameter
TSURFACE==6).
-----------------------------------------------------------
Greenland: Optional linear or exponential interpolation
function for glacial-index-based precipitation forcing
(parameter PRECIP_ANOM_INTERPOL).
-----------------------------------------------------------------
V2.4: Implementation of an elastic lithosphere (ELRA model),
based on Sascha Knell's diploma thesis
(parameter REBOUND==2)
-----------------------------------------------------------
Implementation of Bernd Muegge's conservative first-order
upstream scheme for the age equation
(parameters ADV_HOR==3 and ADV_VERT==3).
-----------------------------------------------------------
Antarctica, Scandinavia (Greenland see V2.2):
- Precipitation instead of solid accumulation used as
input.
- Reeh's degree day model with statistical fluctuations,
supplemented by explicit consideration of rainfall.
- Net surface mass balance computed as precipitation minus
runoff (previously solid accumulation minus melting).
- Optional climate forcing by glacial index and prescribed
LGM anomalies for surface temperature and precipitation
(parameters TSURFACE==5 and ACCSURFACE==5).
-----------------------------------------------------------
Northern-hemisphere module no longer up-to-date, therefore
deleted for the time being.
-----------------------------------------------------------
Compatibility check between version number of SICOPOLIS
and version number in header file.
-----------------------------------------------------------------
V2.4.1: Antarctica, Scandinavia, Greenland:
- Optional computation of surface melting (ablation)
by the positive-degree-day (PDD) method
or the linear-temperature-index (LTI) method
(parameter ABLSURFACE).
- Computation of positive degree days (subroutine pdd)
changed from annual sinus cycle of the surface
temperature to direct use of monthly-mean temperatures.
---------------------------------------------------------
Scandinavia:
- Climate input (surface temperature, precipitation)
changed from seasonal to monthly-mean values.
- Optional horizontal resolutions 40, 20 or 10 km.
-----------------------------------------------------------------
V2.5: Basal sliding now computed in new subroutine calc_vxy_b.
Parameters of sliding law are set in the header file
(previously in phys_para file). New options: Weertman
exponents can be chosen freely, alternative use of
full or reduced pressure in sliding law.
-----------------------------------------------------------
Antarctica, Greenland, Scandinavia:
Two variants of PDD, either with instantaneous runoff of
rainfall (ABLSURFACE==1), or with contribution of rainfall
to formation of superimposed ice (ABLSURFACE==2).
Linear-temperature-index (LTI) method is now chosen by
ABLSURFACE==3.
-----------------------------------------------------------
North- and south-polar cap of Mars:
In addition to the density and the heat conductivity,
now the specific heat is also computed as a
volume-fraction-weighed mean of the ice and dust values,
respectively. Function c_val changed accordingly.
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EISMINT Phase 2 Simplified Geometry Experiment:
Input file surf_para_emtp2sge.dat and subroutine surf_para
deleted. Parameters now defined in header file.
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Minimum bedrock elevation for extent of marine ice
defined by new variable z_mar. Can be chosen as a constant
(MARGIN==2, old option), as proportional to the sea-level
stand (MARGIN==3, new option) or as a piecewise linear
function of sea level (MARGIN==4, new option; as proposed
by Zweck and Huybrechts, 2005).
-----------------------------------------------------------------
V2.6: New module for ISMIP HEINO included (defined by macro
HEINO).
-----------------------------------------------------------
Additional output of the basal frictional heating in the
time-series file for the ice-core locations.
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All constants throughout the program defined consistently
as double-precision constants.
-----------------------------------------------------------
New global parameters pi, pi_inv, pi_180, pi_180_inv, eps.
-----------------------------------------------------------------
V2.7: Special treatment for the chasms of the Martian NPC (Chasma
Borealis) and SPC (Chasma Australis) implemented (optional,
parameter CHASM==2). Chasm regions defined in additional
mask file -> larger geothermal heat flux and wind erosion
rate active within prescribed time interval (specified in
header file).
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ISMIP HEINO: Time-series output for the sediment region
("Hudson Bay, Hudson Strait") in new file runname.sed.
-----------------------------------------------------------
Improved restart: Time derivatives dzs_dtau, dzm_dtau,
dzb_dtau, dH_c_dtau and dH_t_dtau written to time-slice
files and read by restart routine topography3. Further,
Q_b_tot is computed as the sum of Q_bm and Q_tld in
initialization routine sico_init.
-----------------------------------------------------------
In addition to Q_b_tot (formerly called Q_mean), now also
limitations of Q_bm and Q_tld with the same lower and upper
limits, QB_MIN and QB_MAX, respectively.
-----------------------------------------------------------
In subroutine output2 Reinhard Calov's method for computing
the ice equivalent of the water volume below the sea level
(V_ges_redu) implemented.
-----------------------------------------------------------------
V2.7.1: Martian ice caps (NMARS, SMARS):
New topography inputs based on the MOLA MEGDR data with
64 pix/deg resolution. Optional horizontal resolutions
20, 10 or 5 km.
-----------------------------------------------------------------
V2.7.2: x and y coordinates of the origin point (i,j) = (0,0)
now defined in header file as X0 and Y0.
---------------------------------------------------------
Optional computation of the evolution of the free
surface as usual (parameter ZS_EVOL==1),
or keeping the free surface fixed on the initial
topography (parameter ZS_EVOL==0).
---------------------------------------------------------
Greenland:
Update of the ice-core positions according to Dahl-Jensen
(pers. comm. 2006) and inclusion of the planned NEEM
core.
---------------------------------------------------------
Martian ice caps (NMARS, SMARS):
New version of module instemp for the LIT scheme
implemented.
-----------------------------------------------------------------
V2.8: Greenland:
Optional special sliding law for the North-East Greenland
Ice Stream NEGIS (parameter ICE_STREAM==2).
Surface meltwater effect on basal sliding implemented.
-----------------------------------------------------------
ISMIP HEINO:
Optional 25-km resolution implemented (in addition to the
standard resolution of 50 km).
-----------------------------------------------------------
Antarctica:
Re-formatting and re-naming of the input data (now same
style and units like for Greenland). Topography input newly
created from RAMPDEM V2 and BEDMAP data-sets, with an
additional 20-km resolution implemented.
-----------------------------------------------------------------
V2.8.1: Northern-hemisphere module reintroduced, topography
files newly created for horizontal resolutions of
80, 40 and 20 km.
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Explicit introduction of the evaporation (variable evap).
In the modules for the terrestrial ice sheets, evap is
set to zero, whereas in the modules for the Martian
ice caps, evap accounts for the entire ablation.
---------------------------------------------------------
ISMIP HEINO:
Introduction of the option ANF_DAT==1, which defines the
initial topography as a thin ice layer (with a thickness
of 2*H_MIN) everywhere on the land area.
-----------------------------------------------------------------
V2.9: New module for Tibet included (defined by macro TIBET).
-----------------------------------------------------------
Greenland:
Parameterization for the surface meltwater effect on basal
sliding changed; additional dependence on ice thickness
and possible nonlinear dependence on runoff.
-----------------------------------------------------------
Topography files (for zs, zb, zb0, mask) can now be
specified in the header file.
*****************************************************************
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