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Greenhouse Gases (GHG) Forcing Specifications

The Greenhouse Gas (GHG) forcing pipeline ingests CMIP7 global-mean annual surface volume mixing ratios for 9 primary greenhouse gas species, converts them into mass mixing ratios (MMR), linearly interpolates values to January 1, and directly updates the model climate forcing namelist (&clmchfcg) in the downstream ACCESS-ESM1.6 configurations.

Physical Domain & Scientific Scope

  • Species Modeled (9 gases): Carbon Dioxide (co2), Methane (ch4), Nitrous Oxide (n2o), CFC-11 (cfc11), CFC-12 (cfc12), CFC-113 (cfc113), HCFC-22 (hcfc22), HFC-125 (hfc125), and HFC-134a (hfc134a).
  • Source Representation: Global-mean annual timeseries (yr, gm) distributed in NetCDF format via input4MIPs.
  • Target Representation: In-memory array of mass mixing ratios written into the Unified Model &clmchfcg namelist group, dimensioned (nyears, 11) across the 11 UM radiatively active gases.
  • Temporal Interpolation Scheme: CMIP7 source concentrations represent annual means centered at mid-year. Because the UM radiation scheme linearly interpolates between specified annual control points, mid-year values are interpolated to January 1 (\(t_{Jan1} = 0.5 \times (t_{yr} + t_{yr+1})\)) so that UM monthly integration reproduces the annual means.

Controlling Suite Switches

The execution, scenario extension, and downstream configuration synchronization for greenhouse gases are controlled by parameters in rose-suite.conf:

  • Master Activation Switch: ANCIL_CREATE_GHG = true
    When set to false, greenhouse gas processing and associated namelist patching tasks are excluded from the execution graph.
  • Experiment Activation: Governed by USE_EXP['PI'], USE_EXP['HI'], and USE_EXP['SM'].
  • Scenario Extension Controls (EXTEND_SM_GHG):
    Controls whether future pathways concatenate extension files (2101–2200) to cover up to 2150 with --ext:
    • 'h': True (Extended to 2150 via CR-h-ext-1-1-0)
    • 'hl': False (Bounded to 2100)
    • 'm': False (Bounded to 2100)
    • 'vl': True (Extended to 2150 via CR-vl-ext-1-1-0)
  • Downstream Configuration Branching:
    Greenhouse gases directly patch the &clmchfcg namelist in clones of access-esm1.6-configs. The source branches are configured via GIT_CONFIG_BRANCH_PRE (dev for PI/HI, pl for SM) and suffixes GIT_CONFIG_BRANCH_SUF (piControl, historical) / GIT_SM_CONFIG_BRANCH_SUF (scen7-<scen>). Remote push is gated by GIT_CONFIG_BRANCH_PUSH = false.
  • Reference: See Suite Configuration & Parameters Reference for full object definitions.

1. Pre-Industrial Experiment (PI)

PI_ancil_ghg

  • 1. Description & Purpose:
    Extracts perpetual pre-industrial (year 1850) global-mean greenhouse gas concentrations for the 9 species from the CMIP7 historical dataset, converts them to mass mixing ratios, and patches the &clmchfcg namelist in the pre-industrial configuration branch.
  • 2. CLI Arguments Passed:
    python -m esm1p6_ancil.ghg.cmip7_PI_ghg_generate \
    --ancil-target-dirname "${VAR.ANCIL_TARGET_PATH}" \
    # Current: "/g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/$(isodatetime -f CCYY.MM.DD)"
    --cmip7-source-data-dirname "${VAR.CMIP7_SOURCE_PATH}" \
    # Current: "/g/data/qv56/replicas/input4MIPs/CMIP7"
    --esm15-inputs-dirname "${VAR.ESM15_INPUTS_PATH}" \
    # Current: "/g/data/vk83/configurations/inputs/access-esm1p5"
    --dataset-version "${CMIP7_GHG_VERSION}" \
    # Current: "CR-CMIP-1-0-0"
    --dataset-vdate "${CMIP7_GHG_VDATE}" \
    # Current: "v20250228"
    --dataset-date-range "${CMIP7_GHG_DATE_RANGE}"
    # Current: "1750-2022"
  • 3. Input4MIPs Versions & Temporal Metadata:
    • Dataset Version: ${CMIP7_GHG_VERSION} (CR-CMIP-1-0-0)
    • Version Date (vdate): ${CMIP7_GHG_VDATE} (v20250228)
    • Input Date Range: ${CMIP7_GHG_DATE_RANGE} (1750-2022)
    • Extracted Year: 1850
  • 4. Input4MIPs Directory Path & Filenames:
    • Directory Path: ${VAR.CMIP7_SOURCE_PATH}/CMIP/CR/${CMIP7_GHG_VERSION}/atmos/yr/{ghg}/gm/${CMIP7_GHG_VDATE}/
      (Evaluated: /g/data/qv56/replicas/input4MIPs/CMIP7/CMIP/CR/CR-CMIP-1-0-0/atmos/yr/{ghg}/gm/v20250228/)
    • Filenames (9 gases): {ghg}_input4MIPs_GHGConcentrations_CMIP_${CMIP7_GHG_VERSION}_gm_${CMIP7_GHG_DATE_RANGE}.nc
  • 5. Python Scripts & Functions:
    • Main Script / Entrypoint: esm1p6_ancil.ghg.cmip7_PI_ghg_generate
    • Key Functions Called: load_cmip7_ghg_point_mmr, cmip7_ghg_mmr, cmip7_scale, cmip7_pro_greg_date_constraint_from_years, cmip7_ghg_update_namelists_file, format_namelist
    • Shared Libraries: iris, cftime, numpy, f90nml
  • 6. Function-Level Cube Transformations & Constraints:
    • Input Cubes & Coordinates: 1D NetCDF cubes loaded via iris.load_cube per gas species with 1D Proleptic Gregorian time coordinate. Validates attribute assert ghg == cube.metadata.attributes["variable_id"].
    • Constraints Applied: Date constraint cmip7_pro_greg_date_constraint_from_years(1850, 1850) filtering point cftime.DatetimeProlepticGregorian(1850, 1, 1) <= cell.point <= cftime.DatetimeProlepticGregorian(1850, 12, 31).
    • Coordinate Bounds & Manipulation: Single annual point extracted without bounds. Scaled from volume mixing ratio (parts per volume) to mass mixing ratio via molar mass ratios: $\(\text{MMR} = \text{VMR} \times \frac{M_{\text{gas}}}{M_{\text{air}}}\)$
    • Created / Output Cubes: Scalar float values assembled into an 11-species row vector passed to cmip7_ghg_update_namelists_file.
  • 7. Produced File Versions & Date Ranges:
    None (Direct namelist generation). Represents perpetual year 1850 conditions.
  • 8. Produced File Directory Paths & Filenames:
    None. No .anc or binary data files created.
  • 9. Namelist File & Variable Updates:
    • Target File: ${GIT_PI_CONFIG_DIR}/atmosphere/namelists
    • Namelist Group: &clmchfcg
    • Variables Updated: 
      l_clmchfcg = .TRUE.
clim_fcg_nyears = 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
clim_fcg_years = 1850
clim_fcg_levls = <1850 MMR values for 11 species>
clim_fcg_rates = -32768.0

2. Historical Experiment (HI)

HI_ancil_ghg

  • 1. Description & Purpose:
    Reads CMIP7 historical annual global-mean surface concentrations for the 9 GHG species from 1750 to 2022, converts volume mixing ratios to mass mixing ratios, linearly interpolates values to January 1 across the model timeframe 1850–2024, and patches the &clmchfcg namelist in the historical configuration branch.
  • 2. CLI Arguments Passed:
    python -m esm1p6_ancil.ghg.cmip7_HI_ghg_generate \
    --ancil-target-dirname "${VAR.ANCIL_TARGET_PATH}" \
    # Current: "/g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/$(isodatetime -f CCYY.MM.DD)"
    --cmip7-source-data-dirname "${VAR.CMIP7_SOURCE_PATH}" \
    # Current: "/g/data/qv56/replicas/input4MIPs/CMIP7"
    --esm15-inputs-dirname "${VAR.ESM15_INPUTS_PATH}" \
    # Current: "/g/data/vk83/configurations/inputs/access-esm1p5"
    --dataset-version "${CMIP7_GHG_VERSION}" \
    # Current: "CR-CMIP-1-0-0"
    --dataset-vdate "${CMIP7_GHG_VDATE}" \
    # Current: "v20250228"
    --dataset-date-range "${CMIP7_GHG_DATE_RANGE}"
    # Current: "1750-2022"
  • 3. Input4MIPs Versions & Temporal Metadata:
    • Dataset Version: ${CMIP7_GHG_VERSION} (CR-CMIP-1-0-0)
    • Version Date (vdate): ${CMIP7_GHG_VDATE} (v20250228)
    • Input Date Range: ${CMIP7_GHG_DATE_RANGE} (1750-2022)
    • Processed Model Timeline: 1850-2024 (175 annual points)
  • 4. Input4MIPs Directory Path & Filenames:
    • Directory Path: ${VAR.CMIP7_SOURCE_PATH}/CMIP/CR/${CMIP7_GHG_VERSION}/atmos/yr/{ghg}/gm/${CMIP7_GHG_VDATE}/
      (Evaluated: /g/data/qv56/replicas/input4MIPs/CMIP7/CMIP/CR/CR-CMIP-1-0-0/atmos/yr/{ghg}/gm/v20250228/)
    • Filenames (9 gases): {ghg}_input4MIPs_GHGConcentrations_CMIP_${CMIP7_GHG_VERSION}_gm_${CMIP7_GHG_DATE_RANGE}.nc
  • 5. Python Scripts & Functions:
    • Main Script / Entrypoint: esm1p6_ancil.ghg.cmip7_HI_ghg_generate
    • Key Functions Called: load_cmip7_ghg_series_mmr, cmip7_ghg_update_namelists_file, cmip7_ghg_namelist_str, cmip7_ghg_mmr, cmip7_scale, cmip7_pro_greg_date_constraint_from_years, read_namelists_lines_up_to, format_namelist
    • Shared Libraries: iris, cftime, numpy, f90nml
  • 6. Function-Level Cube Transformations & Constraints:
    • Input Cubes & Coordinates: 1D NetCDF cubes loaded via iris.load_cube per gas species, with time coordinate defined on the Proleptic Gregorian calendar. Validates attribute assert ghg == full_cube.metadata.attributes["variable_id"].
    • Constraints Applied:
      • Date range constraint: cmip7_pro_greg_date_constraint_from_years(1850, 2024) filtering points within 1850-01-01 to 2024-12-31.
      • Annual point constraint: cmip7_pro_greg_date_constraint_from_years(year, year) in extraction loop.
    • Coordinate Bounds & Manipulation:
      • Mid-year values interpolated to Jan 1 (0.5 * (val[:-1] + val[1:])).
      • Backwards extrapolation for first year (beg_year_cube.data[0] = val[0] + 0.5 * (val[0] - val[1])), setting time point to January 1, 00:00:00.
      • Time bounds dropped completely (beg_year_cube_time.bounds = None, new_cube_time.bounds = None).
      • Concatenates backwards-extrapolated cube with main cube via iris.cube.CubeList.concatenate_cube() after iris.util.unify_time_units and iris.util.equalise_attributes.
    • Created / Output Cubes: Produces sliced scalar year_cube instances converted via cmip7_ghg_mmr into mass mixing ratio floating point series passed directly to namelist construction.
  • 7. Produced File Versions & Date Ranges:
    None (Direct namelist generation). Temporal coverage encoded into namelist: 1850–2024 (175 annual points).
  • 8. Produced File Directory Paths & Filenames:
    None. No .anc or binary data files created.
  • 9. Namelist File & Variable Updates:
    • Target File: ${GIT_HI_CONFIG_DIR}/atmosphere/namelists
    • Namelist Group: &clmchfcg
    • Variables Updated: 
      l_clmchfcg = .TRUE.
clim_fcg_nyears = 175, 175, 175, 175, 175, 175, 175, 175, 175, 175, 175
clim_fcg_years = 1850..2024
clim_fcg_levls = <175 rows of MMR values for 11 species>
clim_fcg_rates = -32768.0

3. ScenarioMIP Experiment (SM)

SM_{h,hl,m,vl}_ancil_ghg

Tasks generate future greenhouse gas concentration timeseries across the four ScenarioMIP pathways (h, hl, m, vl). Extension to 2150 is controlled per scenario via EXTEND_SM_GHG[SCEN].

  • 1. Description & Purpose:
    Reads ScenarioMIP high-emissions (h) greenhouse gas concentrations, concatenates extension dataset chunks (2101–2200) when EXTEND_SM_GHG['h'] is active (--ext) to cover the timeline to 2150, extrapolates annual values to January 1, and patches the &clmchfcg namelist in the gen-scen7-h-<UUID> branch.
  • 2. CLI Arguments Passed:
    python -m esm1p6_ancil.ghg.cmip7_SM_ghg_generate \
    --ancil-target-dirname "${VAR.ANCIL_TARGET_PATH}" \
    # Current: "/g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/$(isodatetime -f CCYY.MM.DD)"
    --cmip7-source-data-dirname "${VAR.CMIP7_SOURCE_PATH}" \
    # Current: "/g/data/qv56/replicas/input4MIPs/CMIP7"
    --esm15-inputs-dirname "${VAR.ESM15_INPUTS_PATH}" \
    # Current: "/g/data/vk83/configurations/inputs/access-esm1p5"
    --dataset-version "${CMIP7_SM_GHG_VERSION[SCEN]}" \
    # Current: "CR-h-1-1-0"
    --dataset-vdate "${CMIP7_SM_GHG_VDATE[SCEN]}" \
    # Current: "v20260327"
    --dataset-date-range "${CMIP7_SM_GHG_DATE_RANGE}" \
    # Current: "2022-2100"
    --ext \
    --dataset-ext-version "${CMIP7_SM_EXT_GHG_VERSION[SCEN]}" \
    # Current: "CR-h-ext-1-1-0"
    --dataset-ext-vdate "${CMIP7_SM_EXT_GHG_VDATE[SCEN]}" \
    # Current: "v20260327"
    --dataset-ext-date-range "${CMIP7_SM_EXT_GHG_DATE_RANGE}"
    # Current: "2101-2200"
  • 3. Input4MIPs Versions & Temporal Metadata:
    • Base Dataset: ${CMIP7_SM_GHG_VERSION['h']} (CR-h-1-1-0), ${CMIP7_SM_GHG_VDATE['h']} (v20260327), Date Range: ${CMIP7_SM_GHG_DATE_RANGE} (2022-2100)
    • Extension Dataset: ${CMIP7_SM_EXT_GHG_VERSION['h']} (CR-h-ext-1-1-0), ${CMIP7_SM_EXT_GHG_VDATE['h']} (v20260327), Date Range: ${CMIP7_SM_EXT_GHG_DATE_RANGE} (2101-2200)
    • Model Target Range: 2022-2150 (129 annual values)
  • 4. Input4MIPs Directory Path & Filenames:
    • Base: ${VAR.CMIP7_SOURCE_PATH}/ScenarioMIP/CR/${CMIP7_SM_GHG_VERSION['h']}/atmos/yr/{ghg}/gm/${CMIP7_SM_GHG_VDATE['h']}/{ghg}_input4MIPs_GHGConcentrations_ScenarioMIP_${CMIP7_SM_GHG_VERSION['h']}_gm_${CMIP7_SM_GHG_DATE_RANGE}.nc
    • Extension: ${VAR.CMIP7_SOURCE_PATH}/ScenarioMIP/CR/${CMIP7_SM_EXT_GHG_VERSION['h']}/atmos/yr/{ghg}/gm/${CMIP7_SM_EXT_GHG_VDATE['h']}/{ghg}_input4MIPs_GHGConcentrations_ScenarioMIP_${CMIP7_SM_EXT_GHG_VERSION['h']}_gm_${CMIP7_SM_EXT_GHG_DATE_RANGE}.nc
  • 5. Python Scripts & Functions:
    • Main Script / Entrypoint: esm1p6_ancil.ghg.cmip7_SM_ghg_generate
    • Key Functions Called: load_cmip7_ghg_series_mmr, cmip7_ghg_update_namelists_file, cmip7_ghg_namelist_str, cmip7_ghg_mmr, cmip7_pro_greg_date_constraint_from_years, iris.cube.CubeList.concatenate_cube, iris.util.equalise_attributes, iris.util.unify_time_units
  • 6. Function-Level Cube Transformations & Constraints:
    • Input Cubes: Base scenario cube full_cube (2022–2100) and extension chunk ext_cube (2101–2200) loaded via iris.load_cube.
    • Constraints Applied: Concatenation via CubeList([full_cube, ext_cube]).concatenate_cube() after attribute equalization. Date range constraint cmip7_pro_greg_date_constraint_from_years(2022, 2150) extracts the 2022–2150 timeline.
    • Coordinate Bounds & Manipulation: Linear interpolation to Jan 1 (0.5 * (full[:-1] + full[1:])), final year forward extrapolation (full[-1] + 0.5 * (full[-1] - full[-2])), time bounds cleared (bounds = None), time points assigned Jan 1 of each year.
    • Created / Output Cubes: Sliced annual year_cube instances converted via cmip7_ghg_mmr to MMR series for namelist injection.
  • 7. Produced File Versions & Date Ranges:
    None (Direct namelist generation). Temporal coverage: 2022–2150 (129 annual values).
  • 8. Produced File Directory Paths & Filenames:
    None.
  • 9. Namelist File & Variable Updates:
    • Target File: ${GIT_SM_h_CONFIG_DIR}/atmosphere/namelists
    • Namelist Group: &clmchfcg
    • Variables Updated: l_clmchfcg = .TRUE., clim_fcg_nyears = 129, clim_fcg_years = 2022..2150, clim_fcg_levls, clim_fcg_rates = -32768.0.
  • Dataset Versions: Base CR-hl-1-1-0 (v20260327, 2022-2100); Extension CR-hl-ext-1-1-0 (v20260327, 2101-2200).
  • Script & Invocation: esm1p6_ancil.ghg.cmip7_SM_ghg_generate with --dataset-version "CR-hl-1-1-0".
  • Target Branch & Namelist: ${GIT_SM_hl_CONFIG_DIR}/atmosphere/namelists (&clmchfcg).
  • Dataset Versions: Base CR-m-1-1-0 (v20260327, 2022-2100); Extension CR-m-ext-1-1-0 (v20260327, 2101-2200).
  • Script & Invocation: esm1p6_ancil.ghg.cmip7_SM_ghg_generate with --dataset-version "CR-m-1-1-0".
  • Target Branch & Namelist: ${GIT_SM_m_CONFIG_DIR}/atmosphere/namelists (&clmchfcg).
  • Dataset Versions: Base CR-vl-1-1-0 (v20260327, 2022-2100); Extension CR-vl-ext-1-1-0 (v20260327, 2101-2200).
  • Script & Invocation: esm1p6_ancil.ghg.cmip7_SM_ghg_generate with --dataset-version "CR-vl-1-1-0".
  • Target Branch & Namelist: ${GIT_SM_vl_CONFIG_DIR}/atmosphere/namelists (&clmchfcg).