6.9. Calving

6.9.1. Ice-shelf calving

The options for calving of ice shelves (floating ice) can be selected in the run-specs headers by the parameter ICE_SHELF_CALVING:

  • 1: Unlimited expansion of ice shelves, no calving.

  • 2: Instantaneous calving of ice shelves if the thickness is less than a threshold thickness, specified by the parameter H_CALV.

  • 3: “Float-kill”: Instantaneous removal of all floating ice.

For the Antarctic ice sheet, yearly ISMIP6-type ice-shelf collapse masks can be prescribed (Seroussi et al. [48]). This requires the setting ICE_SHELF_COLLAPSE_MASK = 1 and additional parameters as described in the run-specs headers.

6.9.2. Marine-ice calving

For calving of grounded marine ice, the following options are available:

  • Parameterization for “underwater-ice” calving (Dunse et al. [12]).
    To be selected by the following combination of run-specs-header parameters:
    MARGIN = 2, MARINE_ICE_FORMATION = 2, MARINE_ICE_CALVING = 9.
    Further parameters (CALV_UW_COEFF, R1_CALV_UW, R2_CALV_UW) as described in the run-specs headers.

For the Greenland ice sheet, yearly ISMIP6-type retreat masks can be prescribed (Goelzer et al. [16]). This requires the setting RETREAT_MASK = 1 and additional parameters as described in the run-specs headers.