User Instructions for PISM PIK

Here you find some additional features of the PISM project (https://github.com/pism/pism) that will be soon merged into the main development trunk.

In the following you find some intructions how to use those modules:

pik_pdd_scheme_07:

• For precipitation scaling with air temperature using an expontential function result.scale(exp(0.05*dT)) use the -paleo_precip modifier. The parameter can be changed using a pism_override.cdl file (see below). Do we need a precipitation_standard field to enable restart from file? Shouldn't be an issue if the forcing file is external... However, there is no lapse_rate considered for precipitation, not is it point-wise dependent on the surface temperature...

• PDD parameters can be changed using a pism_override.cdl file rather than adding/setting options...

  netcdf pism_parameter { variables: byte pism_overrides;

  pism_overrides:atmosphere.precip_exponential_factor_for_temperature = 0.07041666667;

  pism_overrides:surface.pdd.factor_snow = 0.0032967032967033; pism_overrides:surface.pdd.factor_ice = 0.00879120879120879; pism_overrides:surface.pdd.std_dev = 5.0; } //ncgen -o pism_config_override.nc pism_parameter.cdl //bed_config="-config_override ${INITDIR}/beddef_config.nc"

read_kill_ocean_mask_07:

• Identify the -ocean_kill_file and use additional option -ocean_kill_mask to read the ocean_kill_mask instead of ice thickness and bed topography, to calculate ocean_kill_mask

paleo_init_07:

• Running an (simple inversion) optimization method for the till friction angle analogous to Pollard et al., 2012, where tauc has been optimized with respect to a target surface elevation (Bedmap2). Use option -iterative_phi filename to read usurf as target. Parameters can be set for period of adjustments -tphi_inverse 500, relative surface anomaly -hphi_inverse 500, maximum till friction angle -phimax_inverse 60, minimal till friction angle for marine sediments-phimin_inverse 1 and a convergence criterion -phimod_inverse 0.01 of change in surface elevation per year for varied till friction angle.

cavity:

• Ocean Box Model is now named PICaM (Potsdam Ice shelf CAvity Model) and is the transferred model of ocean_box_model_06.

pik_dev_07:

• Merged development branch, where all individual developments are included.

Generally be aware that all input files use double values to avoid errors due to misfitting domains!

ncap2 -O -s 'x=double(x);y=double(y)' filename.nc or ncks -A -v x,y initfile.nc forcefile.nc