Disabling sub-models¶

Certain major model components, unlike more peripheral ones like bed deformation or calving, are “on” by default. They do not need to be turned on explicitly. For example, the SIA computation is so common that it would be a hassle to require an option to turn it on every time you need it.

But sometimes one wants to disable particular components, during model spin-up, for example. PISM has the following “off” switches:

setting geometry.update.enabled to “false” disables the mass-continuity (conservation of mass) step
setting energy.model to “none” disables the conservation of energy computation
setting energy.model to “cold” makes PISM use temperature instead of enthalpy in the energy conservation code
setting stress_balance.model to “none” disables the stress balance computation (useful for testing surface mass balance inputs)