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Experiment Summary: Historical (HI)

The Historical (HI or historical) experiment simulates the continuous transient evolution of Earth's climate from 1850 to 2023, forced by observed historical emissions, atmospheric concentrations, solar variability, and volcanic eruptions.

Physical Forcing Rationale & Setup

The historical forcing suite provides transient, continuous boundary conditions across the 175-year timeline:

  • Greenhouse Gases: Annual global-mean surface concentrations for 9 species from 1850 to 2024 interpolated to January 1 and injected into &clmchfcg.
  • Total Solar Irradiance: Transient annual solar variability from SOLARIS-HEPPA padded from 1700 to 2300 in TSI_CMIP7_ESM.
  • Volcanic Optical Depth: Monthly 4-band stratospheric aerosol optical depth (SAOD) from UOEXETER capturing major historical eruptions (Krakatoa, Mount Pinatubo, El Chichón) in volcts_cmip7.dat.
  • Aerosol & DMS Emissions: Monthly gridded emissions of anthropogenic BC, OC, and SO2 from CEDS alongside marine DMS.
  • Biomass Burning: Monthly particulate emissions from BB4CMIP7.
  • Reactive Nitrogen: Monthly deposition fluxes from FZJ.
  • Ozone: Monthly 3D zonal-mean ozone concentrations on N96 L85 derived from UKESM1.

Workflow Switches & Selectors

The execution of Historical experiment tasks is governed by parameters in rose-suite.conf:

  • Experiment Activation Switch: USE_EXP['HI'] = True
    HI is registered in MAIN_EXPS = ['HI', 'PI', 'SM']. When set to False, all 12 historical tasks are excluded from the Cylc task DAG.
  • Master Forcing Toggles:
    Controlled by 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 ${GIT_CONFIG_BRANCH_PRE['HI']}-${GIT_CONFIG_BRANCH_SUF['HI']} (dev-historical) from ${GIT_ORG_URL}/${GIT_CONFIG_REPO}.git into ${CYLC_WORKFLOW_SHARE_DIR}/HI_${GIT_CONFIG_REPO}. Commits patched atmosphere/namelists to gen-${GIT_CONFIG_BRANCH_SUF['HI']}-${UNIQUE_NAME} (gen-historical-<UUID>), and conditionally pushes if GIT_CONFIG_BRANCH_PUSH = true.
  • Reference: See Suite Configuration & Parameters Reference for full object declarations.

Complete Task Roster for Historical

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

Task Name Forcing Domain Python Script Entrypoint Primary Input / Dataset Output Type / Destination Technical Specification
HI_ancil_ghg Greenhouse Gases ghg.cmip7_HI_ghg_generate CR-CMIP-1-0-0 (gm yr) Namelist patch (&clmchfcg) View Card
HI_ancil_aerosol_BC Aerosols aerosol.cmip7_HI_BC_interpolate CEDS-CMIP-2025-04-18 .anc (BC_1849_2023_cmip7.anc) View Card
HI_ancil_aerosol_Bio Aerosols aerosol.cmip7_HI_Bio_interpolate BB4CMIP7 biomass .anc (Bio_1849_2023_cmip7.anc) View Card
HI_ancil_aerosol_OC Aerosols aerosol.cmip7_HI_OC_interpolate CEDS-CMIP-2025-04-18 .anc (OCFF_1849_2023_cmip7.anc) View Card
HI_ancil_aerosol_SO2 Aerosols aerosol.cmip7_HI_SO2_interpolate CEDS-CMIP + ESM1.5 DMS .anc (scycl_1849_2023_cmip7.anc) View Card
HI_ancil_nitrogen Nitrogen nitrogen.cmip7_HI_nitrogen_generate FZJ-CMIP-nitrogen-1-2 .anc (Ndep_1849_2023_cmip7.anc) View Card
HI_ukesm_ancil_ozone Ozone UKESM ozone toolchain UKESM1 annual NetCDF Intermediate NetCDF View Card
HI_ancil_ozone Ozone ozone.cmip7_HI_ozone_generate Intermediate NetCDF .anc (ozone_1849_2023_cmip7.anc) View Card
HI_ancil_solar Solar solar.cmip7_HI_solar_generate SOLARIS-HEPPA-CMIP-4-6 ASCII TSI_CMIP7_ESM View Card
HI_ancil_volcanic Volcanic volcanic.cmip7_HI_volcanic_generate UOEXETER-CMIP-2-2-1 ASCII volcts_cmip7.dat View Card
HI_git_clone_checkout Git Sync Bash (git clone) access-esm1.6-configs Local workspace checkout View Card
HI_git_commit_push Git Sync Bash (git commit/push) Modified atmosphere/namelists Downstream git configuration branch View Card

Downstream Configuration Integration

Artifacts feed directly into the dev-historical configuration branch in access-esm1.6-configs:

  • Namelist Updates:
    • atmosphere/namelists: Populates &clmchfcg with 175 annual points (1850–2024) of mass mixing ratios for the 11 greenhouse gas species.
  • Ancillary Installation: Files installed into /g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/<DATE>/modern/historical/:
    • atmosphere/aerosol/global.N96/<DATE>/ (BC_1849_2023_cmip7.anc, Bio_1849_2023_cmip7.anc, OCFF_1849_2023_cmip7.anc, scycl_1849_2023_cmip7.anc)
    • atmosphere/nitrogen/global.N96/<DATE>/ (Ndep_1849_2023_cmip7.anc)
    • atmosphere/forcing/global.N96/<DATE>/ (ozone_1849_2023_cmip7.anc, TSI_CMIP7_ESM, volcts_cmip7.dat)

Execution Flow & Dependencies

graph TD subgraph PreReqs["Prerequisites"] O3Clone["git_clone_ozone_scripts"] --> O3Install["install_ozone_scripts"] end subgraph ParallelTasks["Concurrent Ancillary and Forcing Tasks"] BC["HI_ancil_aerosol_BC"] Bio["HI_ancil_aerosol_Bio"] OC["HI_ancil_aerosol_OC"] SO2["HI_ancil_aerosol_SO2"] Ndep["HI_ancil_nitrogen"] O3Stage1["HI_ukesm_ancil_ozone"] --> O3Stage2["HI_ancil_ozone"] Solar["HI_ancil_solar"] Volc["HI_ancil_volcanic"] end subgraph SerialGit["Namelist Git Synchronization"] Clone["HI_git_clone_checkout"] --> GHG["HI_ancil_ghg"] GHG --> Commit["HI_git_commit_push"] end O3Install --> O3Stage1