Experiment Summary: ScenarioMIP (SM)

The Scenario Model Intercomparison Project (ScenarioMIP or SM) simulates future climate projections under alternative socioeconomic development and greenhouse gas emissions pathways spanning 2022 to 2100 (standard timeline) and extended to 2150 (long-term climate commitment and stabilization).

---

Emissions Pathways & Experimental Design

ACCESS-ESM1.6 configures 4 core Tier-1 and Tier-2 ScenarioMIP pathways:

Scenario	Pathway Description	Radiative Forcing Target	Narrative Context
h	High emissions	\(\sim 8.5\,\text{W}\,\text{m}^{-2}\) by 2100	Rapid fossil-fueled growth
hl	High-Low overshoot	High peak declining to low	Carbon removal & peak-and-decline
m	Medium emissions	\(\sim 4.5\,\text{W}\,\text{m}^{-2}\) by 2100	Intermediate climate policy action
vl	Very Low emissions	\(\sim 1.9\,\text{W}\,\text{m}^{-2}\) by 2100	Immediate aggressive mitigation (\(1.5^\circ\text{C}\) target)

2150 Extension Capabilities

Under the extended workflow mode (EXTEND_SM_* = True or CLI flag --ext), the suite automatically concatenates extension input datasets (2101-2200 chunks for GHG and Aerosols) or applies constant-year tiling (tile_constant_years for Ozone to 2151; final-year tiling for Nitrogen) to deliver continuous, validated 2022–2150 forcing fields.

---

Workflow Switches & Selectors

The execution, pathway selection, and temporal extension for ScenarioMIP are controlled centrally in rose-suite.conf:

• Experiment Activation Switch: USE_EXP['SM'] = True
SM is registered in MAIN_EXPS = ['HI', 'PI', 'SM']. When set to False, all ScenarioMIP tasks across all pathways are removed from the Cylc task DAG.
• Pathway Selectors (SCENARIOS & USE_SCEN):
  Active pathways are enumerated in SCENARIOS = ['h', 'hl', 'm', 'vl'] and toggled individually via:
  • USE_SCEN['h'] = True (High)
  • USE_SCEN['hl'] = True (High-Low)
  • USE_SCEN['m'] = True (Medium)
  • USE_SCEN['vl'] = True (Very Low)
• 2150 Extension Dictionaries (EXTEND_SM_*):
  Controls whether --ext is appended to extend the simulation timeline from 2100 to 2150:
  • EXTEND_SM_AEROSOL: {'h': True, 'hl': False, 'm': False, 'vl': True}
  • EXTEND_SM_CO2: {'h': True, 'hl': False, 'm': False, 'vl': True}
  • EXTEND_SM_GHG: {'h': True, 'hl': False, 'm': False, 'vl': True}
  • EXTEND_SM_NITROGEN: {'h': True, 'hl': True, 'm': True, 'vl': True}
  • EXTEND_SM_OZONE: {'h': True, 'hl': True, 'm': True, 'vl': True}
  • EXTEND_SM_SOLAR: True
  • EXTEND_SM_VOLCANIC: True
• Downstream Branch Mapping:
  Clones base branch ${GIT_CONFIG_BRANCH_PRE['SM']}-${GIT_SM_CONFIG_BRANCH_SUF[SCEN]} (e.g. pl-scen7-h, pl-scen7-hl, pl-scen7-m, pl-scen7-vl) from ${GIT_ORG_URL}/${GIT_CONFIG_REPO}.git into ${CYLC_WORKFLOW_SHARE_DIR}/SM_${SCEN}_${GIT_CONFIG_REPO}. Commits patched namelists to gen-${GIT_SM_CONFIG_BRANCH_SUF[SCEN]}-${UNIQUE_NAME} (gen-scen7-<scen>-<UUID>), and conditionally pushes if GIT_CONFIG_BRANCH_PUSH = true.
• Reference: See Suite Configuration & Parameters Reference for full object declarations.

---

Complete Task Roster for ScenarioMIP

The workflow orchestrates 46 tasks supporting ScenarioMIP across the 4 pathways:

1. Per-Scenario Atmospheric Forcings (\(4 \times 8 = 32\) tasks)

Forcing Domain	Task Pattern (<SCEN> in h, hl, m, vl)	Script Entrypoint	Output Ancillary / Target	Technical Specification
Greenhouse Gases	SM_<SCEN>_ancil_ghg	ghg.cmip7_SM_ghg_generate	Namelist &clmchfcg (2022–2150)	View Card
Black Carbon	SM_<SCEN>_ancil_aerosol_BC	aerosol.cmip7_SM_BC_interpolate	BC_<SCEN>_2022_2150_cmip7.anc	View Card
Biomass Burning	SM_<SCEN>_ancil_aerosol_Bio	aerosol.cmip7_SM_Bio_interpolate	Bio_<SCEN>_2022_2150_cmip7.anc	View Card
Organic Carbon	SM_<SCEN>_ancil_aerosol_OC	aerosol.cmip7_SM_OC_interpolate	OCFF_<SCEN>_2022_2150_cmip7.anc	View Card
Sulfur Cycle	SM_<SCEN>_ancil_aerosol_SO2	aerosol.cmip7_SM_SO2_interpolate	scycl_<SCEN>_2022_2150_cmip7.anc	View Card
Nitrogen Dep.	SM_<SCEN>_ancil_nitrogen	nitrogen.cmip7_SM_nitrogen_generate	Ndep_<SCEN>_2022_2150_cmip7.anc	View Card
Ozone (Stage 1)	SM_<SCEN>_ukesm_ancil_ozone	UKESM regridding toolchain	Intermediate NetCDF	View Card
Ozone (Stage 2)	SM_<SCEN>_ancil_ozone	ozone.cmip7_SM_ozone_generate	ozone_<SCEN>_2022_2150_cmip7.anc	View Card

2. Shared Natural & Radiative Forcings (2 tasks)

Task Name	Forcing Domain	Script Entrypoint	Output File	Description
SM_ancil_solar	Solar	solar.cmip7_SM_solar_generate	TSI_CMIP7_ESM	Projection solar variability (2022–2299)
SM_ancil_volcanic	Volcanic	volcanic.cmip7_SM_volcanic_generate	volcts_cmip7.dat	Post-2022 background volcanic optical depth

3. Git Branch Synchronization (8 tasks)

• Clone & Checkout: SM_{h,hl,m,vl}_git_clone_checkout prepares branches gen-scen7-{h,hl,m,vl}-<UUID>.
• Commit & Push: SM_{h,hl,m,vl}_git_commit_push stages and commits the patched &clmchfcg namelists.

4. Interactive Carbon-Cycle CO2 Fluxes (4 tasks)

• ES_{h,hl,m,vl}_ancil_co2 produces CO2_fluxes_{scen}_2022_2150_cmip7.anc for emission-driven runs (View Card).

---

Downstream Configuration Integration

Each ScenarioMIP pathway targets a dedicated configuration branch in access-esm1.6-configs:

• Branch Names: pl-scen7-h, pl-scen7-hl, pl-scen7-m, pl-scen7-vl.
• Namelists Patched: atmosphere/namelists updated with 129 annual points (2022–2150) in &clmchfcg.
• Output Directories: /g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/<DATE>/modern/scen7-<SCEN>/.

---

Execution Flow & Dependencies

graph TD subgraph SharedSetup["Shared Infrastructure"] O3Clone["git_clone_ozone_scripts"] --> O3Install["install_ozone_scripts"] end subgraph PerScenario["Per-Scenario DAG (Parallel for h, hl, m, vl)"] Clone["SM_[SCEN]_git_clone_checkout"] --> GHG["SM_[SCEN]_ancil_ghg"] --> Commit["SM_[SCEN]_git_commit_push"] BC["SM_[SCEN]_ancil_aerosol_BC"] Bio["SM_[SCEN]_ancil_aerosol_Bio"] OC["SM_[SCEN]_ancil_aerosol_OC"] SO2["SM_[SCEN]_ancil_aerosol_SO2"] Ndep["SM_[SCEN]_ancil_nitrogen"] O3_1["SM_[SCEN]_ukesm_ancil_ozone"] --> O3_2["SM_[SCEN]_ancil_ozone"] end subgraph SharedForcing["Shared Natural Forcings"] Solar["SM_ancil_solar"] Volc["SM_ancil_volcanic"] end O3Install --> O3_1