Forcing configuration (namelist.forcing)

namelist.forcing describes how atmospheric boundary conditions are read and processed. It controls the bulk formulae, optional land-ice freshwater, the age tracer mask, and all file names/variables for surface forcing, runoff and SSS restoring.

Sections of the namelist

Section &forcing_exchange_coeff

  • Ce_atm_oce=1.75e-3, Ch_atm_oce=1.75e-3, Cd_atm_oce=1.0e-3 turbulent exchange coefficients over open water for latent heat, sensible heat and momentum.

  • Ce_atm_ice=1.75e-3, Ch_atm_ice=1.75e-3, Cd_atm_ice=1.2e-3 analogous coefficients over sea ice.

  • Swind=0.0 couples ocean surface currents back to the wind stress following Renault et al. (2019); a value of 1 removes ocean-current influence entirely, values between 0 and 1 partially reduce the applied stress.

Section &forcing_bulk

  • AOMIP_drag_coeff=.false. use AOMIP drag coefficients instead of the default NCAR set.

  • ncar_bulk_formulae=.true. enable the Large & Yeager (2004/2009) NCAR bulk formulae. Set to .false. to bypass bulk flux calculations when direct fluxes are supplied.

  • ncar_bulk_z_wind=10.0, ncar_bulk_z_tair=10.0, ncar_bulk_z_shum=10.0 reference heights (m) for wind, air temperature and humidity that must match the forcing dataset (e.g. 10 m for CORE2/JRA55-do, 2 m for NCEP/JRA55).

Section &land_ice

  • use_landice_water=.false. add freshwater from land ice (routed to the ocean surface and available for output when use_landice_water is true).

  • landice_start_mon=5, landice_end_mon=10 active months for land-ice freshwater input.

  • fwf_path=’<add path>’ directory containing the land-ice runoff files used when the feature is enabled.

Section &age_tracer

  • use_age_tracer=.false. add a passive water-mass age tracer to the model state.

  • use_age_mask=.false., age_tracer_path=’<add path>’ optional mask file for age tracer initialization (e.g. to restrict the tracer to certain basins).

  • age_start_year=2000 reference year when the age tracer is set to zero; useful when replaying historical forcing.

Section &nam_sbc

Forcing file names are provided without the year suffix; the code appends .<year>.nc when opening files. All paths are resolved relative to the working directory unless absolute paths are given.

  • nm_xwind_file, nm_ywind_file 10 m wind speed components; nm_xstre_file, nm_ystre_file optionally provide wind stress directly instead of wind speed.

  • nm_humi_file, nm_qsr_file, nm_qlw_file, nm_tair_file, nm_prec_file, nm_snow_file, nm_mslp_file, nm_cloud_file humidity, shortwave, longwave, 2 m air temperature, total precipitation, snowfall, mean sea level pressure and cloud cover forcing files.

  • nm_*_var variable names inside each file (nm_xwind_var, nm_ywind_var, nm_xstre_var, nm_ystre_var, nm_humi_var, nm_qsr_var, nm_qlw_var, nm_tair_var, nm_prec_var, nm_snow_var, nm_mslp_var, nm_cloud_var).

  • nm_nc_iyear=1900, nm_nc_imm=1, nm_nc_idd=1, nm_nc_freq=1, nm_nc_tmid=0 describe the time axis in the forcing files: start year/month/day, number of records per day (1 for daily, 4 for 6-hourly, etc.), and whether timestamps represent mid-interval values (CORE: 1, JRA55: 0).

  • y_perpetual=.false. loop a single forcing year indefinitely (set nm_nc_iyear and provide the matching annual files).

  • l_xwind=.true., l_ywind=.true., l_xstre=.false., l_ystre=.false., l_humi=.true., l_qsr=.true., l_qlw=.true., l_tair=.true., l_prec=.true., l_mslp=.false., l_cloud=.false., l_snow=.true. switches for each forcing component. When l_xstre/l_ystre are .true. the stress fields are used instead of computing stress from wind speed.

  • nm_runoff_file=’<add path>’, runoff_data_source=’JRA55’, runoff_climatology=.false. runoff source and file. Supported sources are 'CORE1'/'CORE2' (single-field climatology), 'JRA55'/'Dai09' (monthly climatology). Set runoff_climatology=.true. to treat the file as a repeating 12-month climatology; .false. expects a transient monthly time series.

  • nm_sss_data_file=’<add path>’, sss_data_source=’CORE2’ sea-surface salinity restoring data and source ('CORE2', 'WOA', 'NONE'). Only used when salinity restoring is enabled in namelist.oce.

  • chl_data_source=’Sweeney’, nm_chl_data_file=’<add path>’, chl_const=0.1 chlorophyll data for shortwave penetration (active when use_sw_pene in namelist.config is .true.). Choose 'Sweeney' for the supplied climatology file or 'None' to use the constant value chl_const.

  • use_runoff_mapper=.false., runoff_basins_file=’<add path>’, runoff_radius=500000. enable and configure the runoff mapper that spreads river discharge over neighbouring coastal cells using the provided basin map and radius.