ESM forcing

Runs forced by Earth-System-Model (ESM) output (ISMIP7, TIPMIP, 1pctCO2) use the yelmox program with the ESM climate backend: [comps] climate = "esm". The backend wraps libs/esm_forcing.f90: a reference climatology at the current surface (lapse rate, precipitation scaling), plus ESM anomalies over historical and projection periods, optional climate variability and subglacial discharge.

Configuration

  • Run phase and calendar. [ctrl] run_step names the group holding the timeline ("spinup" or "transient"), with calendar = True and calendar_ref = 2000.0: the timeline is in calendar years. The same group holds the ESM periods (time_ref, time_hist, time_proj, time_esm_ref) and the variability switches (clim_var, clim_seed).
  • Experiment. [esm]: par_file (the ESM data configuration in input/esm/), experiment, esm_name, use_esm / use_var / use_hist / use_proj, and the physical parameters lapse, f_p, f_ocn, f_polar, dT_threshold, grid_src.
  • Surface mass balance. [comps] surface_method = "climate" takes the ESM’s own SMB (reference + anomaly, corrected from the present-day surface with the SMB elevation gradient); "smbpal" computes it from the ESM temperature and precipitation.
  • Update cadence. [comps] dt_clim = 1.0: the forcing is updated every step.
  • Cold start. [sim] init_kill_shelves (no ice where the present-day bed is ocean) and init_time_thrm (equilibration with topography fixed), shared with the other configurations.

What the backend supplies

  • the atmosphere (tas, pr) for smbpal, or the surface mass balance directly;
  • the ocean at the shelf base (T_shlf, S_shlf and their anomalies), interpolated from the reference ocean with the marine-shelf parameters, so step_shelf passes it straight to the marine shelf;
  • subglacial discharge Qd, landed on Yelmo by couple_to_yelmo.

Output

The shared per-module files (yelmo.nc, isos.nc, mshlf.nc, smbpal.nc, …), plus, with [output] write_clim, esm.nc (the ESM fields on the climate grid) and esm_ts.nc (the forcing averaged over the ice and the floating ice), and, with [output] write_cmip (every dt_cmip), the CMIP-formatted yelmo_cmip.nc and yelmo_ts_cmip.nc.