There are lots of different timesteps and substepping going on in the ACME v1 model (much of which is inherited from v0). This page is an attempt to clarify what values we typically use for these substeps. Note that most of the substep values for dynamics are illustrated in this slide:
This table provides the values we've been using and explanation of what each quantity means.
| ne30 | ne120 before 8/10/16 | ne120 after 8/10/16 | Explanation | |
|---|---|---|---|---|
| dtime | 30 min | 15 min | 15 min | Timestep used for most physics processes and for coupling between physics and dynamics |
| se_nsplit | 2 | dtime/se_nsplit = time between vertical remaps of the semi-Lagrangian vertical coordinate. | ||
| se_qsplit | 1 | dtime/(se_nsplit*se_qsplit) = timestep used for tracer advection | ||
| se_rsplit | 4 | dtime/(se_nsplit*se_qsplit*se_rsplit) = timestep used for dynamics calculations | ||
| hypervis_subcycle | 3 | dtime/(se_nsplit_se_qsplit*se_rsplit*hypervis_subcycle) = timestep used for hyperviscosity calculation | ||
| cld_macmic_num_steps | 6 | Number of times the code surrounding macrophysics + microphysics is subcycled. This means that dtime/cld_macmic_num_steps = timestep used for macrophysics and microphysics. | ||
| clubb_timestep | 300 sec | I'm not sure what this means or how it relates to cld_macmic_num_steps | ||
| IRADSW | 2 steps | How frequently to compute SW radiation (in timesteps). Radiation tendencies are taken from previous steps for steps when radiation is not recalculated. I think some scaling is made to account for zenith angle changes? | ||
| IRADLW | 2 steps | How frequently to compute LW radiation (in timesteps). Radiation tendencies are taken from previous steps for steps when radiation is not recalculated. I think some scaling is made to account for zenith angle changes? |