WRF-SFIRE simulations sometimes crash because of a too large time step. That motivates the use of an adaptive time step for running fire-atmosphere simulations with WRF-SFIRE. The main parameters to control the adaptive time step are defined in the domains section and they are:
Parameter | Default | Definition
use_adaptive_time_step | .false. | T/F use adaptive time stepping, ARW only
step_to_output_time | .true. | if adaptive time stepping, T/F modify the time steps so that the exact history time is reached
target_cfl (max_dom) | 1.2,1.2 | vertical and horizontal CFL <= to this value implies no reason to reduce the time step, and to increase it
max_step_increase_pct (max_dom) | 5,51 | percentage of previous time step to increase, if the max(vert cfl, horiz cfl) <= target_cfl, then the time will increase by max_step_increase_pct
starting_time_step (max_dom) | -1,-1 | flag = -1 implies use 6 * dx (defined in start_em), starting_time_step = 100 means the starting time step
max_time_step (max_dom) | -1,-1 | flag = -1 implies max time step is 3 * starting_time_step, max_time_step = 100 means that the time step will not
min_time_step (max_dom) | -1,-1 | flag = -1 implies max time step is 0.5 * starting_time_step, min_time_step = 100 means that the time step will not
adaptation_domain | 1 | default, all fine grid domains adaptive dt driven by coarse-grid; 2 = Fine grid domain #2 determines the fundamental adaptive dt.
A WRF-SFIRE adaptive time step test was performed in Cheyenne: /glade/u/home/angelfc/project/WRFx/wrfxpy/wksp/wfc-adaptive-test
The results need to be tested and validated against the same simulation but without adaptive time step also in Cheyenne here: /glade/u/home/angelfc/project/WRFx/wrfxpy/wksp/wfc-from-web-2021-09-26_15-15-35-2021-09-26_12:00:00-48