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Experiment Summary: Pre-Industrial Control (PI)

The Pre-Industrial Control (PI or piControl) experiment establishes the unperturbed pre-industrial climate baseline (representative of year 1850 conditions). It serves as the reference benchmark against which historical and scenario climate change forced responses are evaluated.

Physical Forcing Rationale & Setup

The forcing suite provides time-invariant or cyclic climatological boundary conditions:

  • Greenhouse Gases: Constant 1850 global-mean surface concentrations for 9 species patched into &clmchfcg.
  • Total Solar Irradiance: Time-invariant pre-industrial solar constant \(S_0 = 1361.603\,\text{W}\,\text{m}^{-2}\) patched into namelist variable SC in &coupling.
  • Volcanic Aerosols: Mean background stratospheric aerosol optical depth (SAOD) calculated from UOEXETER climatology patched into VOLCTS_val = 0.17 in &coupling.
  • Aerosol & DMS Emissions: 12-month cyclic emissions of anthropogenic BC, OC, and SO2 from CEDS alongside marine DMS from CMIP6.
  • Biomass Burning: 12-month cyclic particulate emissions from BB4CMIP7.
  • Reactive Nitrogen: 12-month cyclic surface deposition fluxes from FZJ.
  • Ozone: 12-month equilibrium 3D ozone concentrations derived from UKESM1.

Workflow Switches & Selectors

The execution of Pre-Industrial Control tasks is governed by parameters in rose-suite.conf:

  • Experiment Activation Switch: USE_EXP['PI'] = True
    PI is registered in MAIN_EXPS = ['HI', 'PI', 'SM']. When set to False, all 12 pre-industrial tasks are excluded from the Cylc task DAG.
  • Master Forcing Toggles:
    Individual components are activated via ANCIL_CREATE_AEROSOL, ANCIL_CREATE_GHG, ANCIL_CREATE_NITROGEN, ANCIL_CREATE_OZONE, ANCIL_CREATE_SOLAR, and ANCIL_CREATE_VOLCANIC.
  • Downstream Branch Synchronization:
    Clones base branch ${GIT_CONFIG_BRANCH_PRE['PI']}-${GIT_CONFIG_BRANCH_SUF['PI']} (dev-piControl) from ${GIT_ORG_URL}/${GIT_CONFIG_REPO}.git into ${CYLC_WORKFLOW_SHARE_DIR}/PI_${GIT_CONFIG_REPO}. Commits patched namelists to gen-${GIT_CONFIG_BRANCH_SUF['PI']}-${UNIQUE_NAME} (gen-piControl-<UUID>), and conditionally pushes if GIT_CONFIG_BRANCH_PUSH = true.
  • Reference: See Suite Configuration & Parameters Reference for full object declarations.

Complete Task Roster for Pre-Industrial Control

The following 12 Cylc workflow tasks generate all necessary ancillaries and namelist patches for the PI configuration:

Task Name Forcing Domain Python Script Entrypoint Primary Input / Dataset Output Type / Destination Technical Specification
PI_ancil_ghg Greenhouse Gases ghg.cmip7_PI_ghg_generate CR-CMIP-1-0-0 (gm yr) Namelist patch (&clmchfcg) View Card
PI_ancil_aerosol_BC Aerosols aerosol.cmip7_PI_BC_interpolate CEDS-CMIP-2025-04-18 .anc (BC_1850_cmip7.anc) View Card
PI_ancil_aerosol_Bio Aerosols aerosol.cmip7_PI_Bio_interpolate BB4CMIP7 biomass .anc (Bio_1850_cmip7.anc) View Card
PI_ancil_aerosol_OC Aerosols aerosol.cmip7_PI_OC_interpolate CEDS-CMIP-2025-04-18 .anc (OCFF_1850_cmip7.anc) View Card
PI_ancil_aerosol_SO2 Aerosols aerosol.cmip7_PI_SO2_interpolate CEDS-CMIP + ESM1.5 DMS .anc (scycl_1850_cmip7.anc) View Card
PI_ancil_nitrogen Nitrogen nitrogen.cmip7_PI_nitrogen_generate FZJ-CMIP-nitrogen-1-2 .anc (Ndep_1850_cmip7.anc) View Card
PI_ukesm_ancil_ozone Ozone UKESM ozone toolchain UKESM1 annual NetCDF Intermediate NetCDF View Card
PI_ancil_ozone Ozone ozone.cmip7_PI_ozone_generate Intermediate NetCDF .anc (ozone_1850_cmip7.anc) View Card
PI_ancil_solar Solar solar.cmip7_PI_solar_generate SOLARIS-HEPPA-CMIP-4-6 (fx) Namelist SC patch (&coupling) View Card
PI_ancil_volcanic Volcanic volcanic.cmip7_PI_volcanic_generate UOEXETER-CMIP-2-2-1 (ext) Namelist VOLCTS_val (&coupling) View Card
PI_git_clone_checkout Git Sync Bash (git clone) access-esm1.6-configs Local workspace checkout View Card
PI_git_commit_push Git Sync Bash (git commit/push) Modified namelists / ancils Downstream git configuration branch View Card

Downstream Configuration Integration

The artifacts generated by the pre-industrial suite feed directly into the dev-piControl configuration branch in access-esm1.6-configs:

  • Namelist Updates:
    • atmosphere/input_atm.nml: Updates SC = 1361.603 and VOLCTS_val = 0.17 in namelist group &coupling.
    • atmosphere/namelists: Updates &clmchfcg with 1850 mass mixing ratios for the 11 radiatively active gases.
  • Ancillary Installation: Files installed into /g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/<DATE>/modern/pre-industrial/:
    • atmosphere/aerosol/global.N96/<DATE>/ (BC_1850_cmip7.anc, Bio_1850_cmip7.anc, OCFF_1850_cmip7.anc, scycl_1850_cmip7.anc)
    • atmosphere/nitrogen/global.N96/<DATE>/ (Ndep_1850_cmip7.anc)
    • atmosphere/forcing/global.N96/<DATE>/ (ozone_1850_cmip7.anc)

Execution Flow & Dependencies

graph TD subgraph PreReqs["Prerequisites"] O3Clone["git_clone_ozone_scripts"] --> O3Install["install_ozone_scripts"] end subgraph ParallelAncils["Independent Ancillary Generators"] BC["PI_ancil_aerosol_BC"] Bio["PI_ancil_aerosol_Bio"] OC["PI_ancil_aerosol_OC"] SO2["PI_ancil_aerosol_SO2"] Ndep["PI_ancil_nitrogen"] O3Stage1["PI_ukesm_ancil_ozone"] --> O3Stage2["PI_ancil_ozone"] end subgraph SerialNamelists["Namelist Sequential Chain"] Clone["PI_git_clone_checkout"] --> GHG["PI_ancil_ghg"] GHG --> Solar["PI_ancil_solar"] Solar --> Volc["PI_ancil_volcanic"] Volc --> Commit["PI_git_commit_push"] end O3Install --> O3Stage1