Module time

This IGM module computes the time step such that:
i) It satisfies the CFL condition (controlled by the parameter processes.time.cfl).
ii) It is lower than a given maximum time step (controlled by the parameter processes.time.step_max).
iii) It aligns exactly with specified saving times (controlled by the parameter processes.time.save).

The module also updates the current simulation time \(t\) in addition to determining the time step.

For stability reasons related to the transport scheme for ice thickness evolution, the time step must adhere to the CFL condition. This condition is governed by the parameter processes.time.cfl, which specifies the maximum number of cells that can be crossed in one iteration (this parameter cannot exceed 1). By default, processes.time.cfl is set to 0.3. Additionally, the time step is constrained by a user-defined maximum time step, processes.time.step_max, and must align with the saving frequency defined by processes.time.save (default: 1 year).

Key parameters of this module include:
- processes.time.start: Defines the simulation start time.
- processes.time.end: Defines the simulation end time.
- processes.time.save: Specifies the frequency at which results are saved (default: 10 years).

Further details on the time step stability conditions can be found in the following paper:

Reference: Jouvet, G., Cordonnier, G., Kim, B., Lüthi, M., Vieli, A., & Aschwanden, A. (2022). Deep learning speeds up ice flow modelling by several orders of magnitude. Journal of Glaciology, 68(270), 651-664.

Contributors: G. Jouvet

Config Structure

time:
  start: 2000.0
  end: 2100.0
  save: 10.0
  cfl: 0.3
  step_max: 1.0

Parameters

Name	Type	Units	Description	Default Value
start	float	y	Start time of the simulation	2000.0
end	float	y	End time of the simulation	2100.0
save	float	y	Frequency of saving the simulation results	10.0
cfl	float	dimless	CFL condition for time stepping	0.3
step_max	float	y	Maximum time step allowed	1.0