6.22. imogen.nml

This file contains two namelists called IMOGEN_RUN_LIST and IMOGEN_ANLG_VALS_LIST. Values from this section are only used if IMOGEN is enabled (i.e. l_imogen = TRUE).

A full IMOGEN experiment consists of three JULES runs, called spin_eq, spin_dyn and tran. Each run is started from the final dump of the previous run. The first two runs behave like an extended spin-up for the full transient run, and as such runs with IMOGEN must have no spin-up (i.e. max_spinup_cycles = 0).

Since IMOGEN calculates the forcing for an entire year at once, an IMOGEN run must have a start time of 00:00:00 on the 1st of January for some year.

IMOGEN is currently restricted to run only on the HadCM3LC grid, i.e. there are 96 x 56 grid cells where each cell has size 3.75 degrees longitude by 2.5 degrees latitude with no Antarctica. This means that:

• nx = 96 and ny = 56.
• The file examples/imogen/data/jules/grid_info.nc should be used to set up the correct latitude, longitude and land fraction, as in the given example.

IMOGEN also uses its own I/O, so it expects IMOGEN specific files in a different format to JULES - this may change in the future. An example of setting up IMOGEN is provided in examples/imogen - this should be used as a guide if creating new files for IMOGEN.

6.22.1. IMOGEN_RUN_LIST namelist members

IMOGEN_RUN_LIST::co2_init_ppmv

Type:real Default:286.085

Initial CO2 concentration (ppmv).

IMOGEN_RUN_LIST::file_scen_emits

Type:character Default:None

If used, file containing CO2 emissions.

This file is expected to be in a specific format - see the IMOGEN example.

IMOGEN_RUN_LIST::file_non_co2_vals

Type:character Default:None

If used, file containing non-CO2 values.

This file is expected to be in a specific format - see the IMOGEN example.

IMOGEN_RUN_LIST::file_scen_co2_ppmv

Type:character Default:None

If used, file containing CO2 values.

This file is expected to be in a specific format - see the IMOGEN example.

IMOGEN_RUN_LIST::anlg

Type:logical Default:T

If TRUE, then use the GCM analogue model.

IMOGEN_RUN_LIST::anom

Type:logical Default:T

If TRUE, then incorporate anomalies.

IMOGEN_RUN_LIST::c_emissions

Type:logical Default:T

If TRUE, CO2 concentration is calculated.

IMOGEN_RUN_LIST::include_co2

Type:logical Default:T

If TRUE, include adjustments to CO2 values.

IMOGEN_RUN_LIST::include_non_co2

Type:logical Default:T

If TRUE, include adjustments to non-CO2 values.

IMOGEN_RUN_LIST::land_feed

Type:logical Default:F

If TRUE, include land feedbacks on atmospheric CO2.

IMOGEN_RUN_LIST::ocean_feed

Type:logical Default:F

If TRUE, include ocean feedbacks on atmospheric CO2.

IMOGEN_RUN_LIST::nyr_emiss

Type:integer Default:241

Number of years of emission data in file.

IMOGEN_RUN_LIST::file_points_order

Type:character Default:None

File containing the mapping of IMOGEN global grid points onto IMOGEN land points (different from the JULES land points).

IMOGEN_RUN_LIST::initialise_from_dump

Type:logical Default:F

Indicates how the IMOGEN prognostic variables will be initialised.

TRUE

Use a dump file (specified in dump_file below) from a previous run with IMOGEN to initialise the IMOGEN prognostics.

FALSE

IMOGEN will handle the initialisation of its prognostics internally.

IMOGEN_RUN_LIST::dump_file

Type:character Default:None

The name of the dump file to initialise from.

Only used if initialise_from_dump = TRUE.

6.22.2. IMOGEN_ANLG_VALS_LIST namelist members

IMOGEN_ANLG_VALS_LIST::q2co2

Type:real Default:3.74

Radiative forcing due to doubling CO2 (W m^-2).

IMOGEN_ANLG_VALS_LIST::f_ocean

Type:real Default:0.711

Fractional coverage of the ocean.

IMOGEN_ANLG_VALS_LIST::kappa_o

Type:real Default:383.8

Ocean eddy diffusivity (W m^-1 K^-1).

IMOGEN_ANLG_VALS_LIST::lambda_l

Type:real Default:0.52

Inverse of climate sensitivity over land (W m^-2 K^-1).

IMOGEN_ANLG_VALS_LIST::lambda_o

Type:real Default:1.75

Inverse of climate sensitivity over ocean (W m^-2 K^-1).

IMOGEN_ANLG_VALS_LIST::mu

Type:real Default:1.87

Ratio of land to ocean temperature anomalies.

IMOGEN_ANLG_VALS_LIST::t_ocean_init

Type:real Default:289.28

Initial ocean temperature (K).

IMOGEN_ANLG_VALS_LIST::nyr_non_co2

Type:integer Default:21

Number of years for which non-co2 forcing is prescribed.

IMOGEN_ANLG_VALS_LIST::dir_patt

Type:character Default:None

Directory containing the patterns.

Files in this directory are expected to be in a specific format - see the IMOGEN example.

IMOGEN_ANLG_VALS_LIST::dir_clim

Type:character Default:None

Directory containing initialising climatology.

Files in this directory are expected to be in a specific format - see the IMOGEN example.

IMOGEN_ANLG_VALS_LIST::dir_anom

Type:character Default:None

Directory containing prescribed anomalies.

Files in this directory are expected to be in a specific format - see the IMOGEN example.

IMOGEN_ANLG_VALS_LIST::file_non_co2

Type:logical Default:F

If true, then non-CO2 radiative forcings are contained within a file.