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Experiment Summary: AMIP (AM)

The Atmospheric Model Intercomparison Project (AMIP or AM) configures atmosphere-only simulations driven by observed monthly sea surface temperatures (SST) and sea-ice concentrations (SIC).

Physical Forcing Rationale & Setup

In coupled climate simulations (like HI and PI), the atmosphere exchanges heat and moisture interactively with the dynamic ocean model (MOM5) and sea ice model (CICE4). In AMIP simulations:

  • Ocean Dynamics Disabled: The ocean is replaced by prescribed, observed monthly boundary condition ancillary files.
  • Prescribed SST: Monthly sea surface skin temperature (Kelvin) driving lower boundary atmospheric fluxes (STASH m01s00i024).
  • Prescribed Sea Ice: Monthly sea-ice fractional area coverage and ice surface properties (STASH m01s00i031 / m01s00i032).
  • Source Observations: Global monthly SST and SIC fields from PCMDI (PCMDI-AMIP-1-1-10) spanning 1870 to 2022.

Workflow Switches & Selectors

The execution and configuration of AMIP boundary generation tasks are governed by parameters in rose-suite.conf:

  • Experiment Activation Switch: USE_EXP['AM'] = True
    When set to False, all 7 AMIP tasks are excluded from the Cylc task DAG.
  • Master Forcing Toggle: ANCIL_CREATE_AMIP = true
    Both USE_EXP['AM'] and ANCIL_CREATE_AMIP must evaluate to true to schedule the AMIP task family.
  • Target Variables: AMIP_VARS = ['seaice', 'sst'].
  • Upstream Toolchain Branching: Clones the UKESM AMIP processing toolchain from ${GIT_ORG_URL}/${GIT_AMIP_SCRIPTS_REPO}.git on branch ${GIT_AMIP_SCRIPTS_BRANCH} (1-port-cmip7-amip-code-for-esm16-site-nci).
  • Reference: See Suite Configuration & Parameters Reference for full object declarations.

Complete Task Roster for AMIP

The following 7 Cylc workflow tasks execute the AMIP boundary generation pipeline:

Task Name Pipeline Stage Script Entrypoint Input / Prerequisite Output Artifact Technical Specification
git_clone_amip_scripts Setup Bash (git clone) ancillary-file-science (1-port-cmip7-amip-code...) Cloned repository View Card
install_amip Setup pip install Cloned repository Installed environment View Card
AM_ukesm_regrid Upstream Regrid UKESM AMIP toolchain PCMDI-AMIP-1-1-10 NetCDF Regridded NetCDF View Card
AM_ukesm_taylor Quality QA UKESM AMIP toolchain Regridded NetCDF Taylor quality report View Card
AM_ukesm_ancil Upstream Ancil UKESM AMIP toolchain Regridded NetCDF Intermediate NetCDF View Card
AM_seaice_ancil_amip UM Ancillary amip.cmip7_AM_amip_generate seaice_amip_n96_gregorian.nc seaice_amip_n96_gregorian.anc View Card
AM_sst_ancil_amip UM Ancillary amip.cmip7_AM_amip_generate sst_amip_n96_gregorian.nc sst_amip_n96_gregorian.anc View Card

Downstream Configuration Integration

Artifacts feed into the amip configuration branch in access-esm1.6-configs:

  • Installation Directory:
    /g/data/${PROJECT}/${USER}/CMIP7/esm1p6_ancil/<ISO_DATE_TODAY>/modern/amip/atmosphere/boundary_conditions/global.N96/<ANCIL_TODAY>/
  • Model Namelist References:
    The generated files are referenced in atmosphere/namelists to drive the lower boundary condition reader for SST and SIC.

Execution Flow & Dependencies

graph LR Clone["git_clone_amip_scripts"] --> Install["install_amip"] Install --> Regrid["AM_ukesm_regrid"] Regrid --> Taylor["AM_ukesm_taylor"] Taylor --> AncilPrep["AM_ukesm_ancil"] AncilPrep --> SeaIce["AM_seaice_ancil_amip"] AncilPrep --> SST["AM_sst_ancil_amip"]