6.2. Initial conditions

6.2.1. Topography

The initial conditions for the ice topography can be chosen in the run-specs headers by the parameter ANF_DAT (“ANF” being a remaining Germanicism in the code, derived from the German word “Anfang” = start, beginning, initial):

  • 1: Present-day initial topography.

  • 2: Ice-free initial topography with relaxed lithosphere.

  • 3: Initial values from previous simulation.

For specifying the topography files, see Section “Model domain, grid and time/Topography”.

6.2.2. Temparature

In case of ANF_DAT = 1, initial conditions for the 3D temperature field must also be prescribed. This is done by the parameter TEMP_INIT:

  • 1: Constant value in the entire ice sheet (defined by parameter TEMP_INIT_VAL).

  • 2: In each ice column equal to the local ice surface temperature.

  • 3: Ice temperature linearly increasing with depth.

  • 4: Ice-temperature profiles from analytical solution for 1D steady-state advection-diffusion equation under the assumption of linearly varying \(v_z\) (Robin [54] solution).

  • 5: Ice temperature from previous simulation.

The settings ANF_DAT = 3, or ANF_DAT = 1 and TEMP_INIT = 5, require specifying an initial-value file, which is typically a time-slice output file from a previous simulation (see Section “Output files”). This is done by assigning the parameter ANFDATNAME a text string with the file name. In addition, the path where this file is located must be given as an option -a /path/to/initial/value/directory to the script sico.sh when running SICOPOLIS (see Section “How to run a simulation”).