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Overview

OpenIFS includes a number of idealised configurations. In this article we explain how to configure the model for an 'aqua-planet' simulation. An aqua-planet is one that includes no topography and no land. It's a highly simplified representation of Earth but useful for a number of studies.

 

Info
titleFurther information

The aquaplanet configuration (enabled by namelist variable LAQUA) is based on the Neale & Hoskins publications:

  • Neale, R. B. and Hoskins B. J., 2000a, A standard test for AGCMs and their physical parameterizations. I: The proposal, Atmos. Sci. Letters, 1, pp. 101-107, DOI: 10.1006/asle.2000.0022
  • Neale, R. B. and Hoskins, B. J., 2000b, A standard test for AGCMs and their physical parameterizations. II: Results for The Met. Office Model, Atmos. Sci. Letters, 1, pp. 108-114, DOI: 10.1006/asle.2000.0024

More recent publications on the aqua-planet:

  • Medeiros, B., et al,2008, Aquaplanets, climate sensitivity, and low clouds. Journal of Climate, DOI: 10.1175/2008JCLI1995.1
  • Blackburn, M., et al. (2013) The Aqua-Planet Experiment (APE): CONTROL SST Simulation. Journal of the Meteorological Society of Japan, 91A. pp. 17-56. ISSN 2186-9057 doi: 10.2151/jmsj.2013-A02

  • Blackburn, M. and Hoskins, B. J. (2013) Context and aims of the Aqua-Planet Experiment. Journal of the Meteorological Society of Japan, 91A. pp. 1-15. ISSN 2186-9057 doi: 10.2151/jmsj.2013-A01

See also for example, the PCMDI Aqua-Planet website.

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Table of Contents

Info

Please note that aqua-planet and other idealized configurations are a research tool and therefore may change between model versions.

For further assistance with idealised configurations of OpenIFS, please contact: openifs-support@ecmwf.int.

Configuration

Configuring OpenIFS for an aqua-planet simulation requires appropriate changes to:

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Code Block
titleEnsure mass conservation: NAMCT0
&NAMCT0
NFRMASSCON=24,      ! frequency of mass conversation fixups (time-steps)

Model physics

There are normally no changes required to Aqua-planet simulations normally use the full model physics and no changes are necessary in the NAEPHY namelist. This controls the behaviour of the model physics and It is included here for completeness.
If necessary edit the fort.4 file (containing the input model namelist) and make sure the settings are as below.

Note in this example, the model physics is turned on (enabled). By setting LEPHYS=false, the model would run an aqua-planet with all the physics switched off.
For more information on these switches see the relevant modules in the model code: yoephy.F90 and yoewcou.F90.

Code Block
titleNamelist settings for model physics: NAEPHY
&NAEPHY
LEPHYS=true,     ! switch the full ECMWF physics package on/off.
LEVDIF=true,     ! turn on/off the vertical diffusion scheme.
LESURF=true,     ! turn on/off the interface surface processes.
LECOND=true,     ! turn on/off the large-scale condensation processes.
LECUMF=true,     ! turn on/off the mass-flux cumulus convection.
LEPCLD=true,     ! turn on/off the prognostic cloud scheme.
LEEVAP=true,     ! turn on/off the evaporation of precipitation
LEVGEN=true,     ! turn on/off Van Genuchten hydrology (with soil type field)
LESSRO=true,     ! turn on/off orographic (VIC-type) runoff
LECURR=false,    ! if true, ocean current boundary condition is used.
LEGWDG=true,     ! turn on/off gravity wave drag.
LEGWWMS=true,    ! turn on/off the Warner-McIntyre-Scinocca non-orographic gravity wave drag scheme.
LEOZOC=true,     ! turn on/off the climatological ozone.
LEQNGT=true,     ! turn on/off the negative humidity fixer.
LERADI=true,     ! turn on/off the radiation scheme.
LERADS=true,     ! turn on/off the interactive surface radiative properties.
LESICE=true,     ! turn on/off the interactive sea-ice processes.
LEO3CH=false,    ! turn on/off the ozone chemistry (for prognostic ozone).
LEDCLD=true,     ! turn on/off the diagnostic cloud scheme.
LDUCTDIA=false,  ! turn on/off computation and archiving of ducting diagnostics.
LWCOU=false,     ! turn on/off coupled wave model (n.b. always off for OpenIFS model).
LWCOU2W=false,   ! turn on/off two-way interaction with the wave model (n.b. always off for OpenIFS model).
/

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The above is all that's necessary to enable aqua-planet in the model. However, you may want to experiment with other model options.

  1. Code Block
    titleInitialisation
    &NAMCT0
N3DINI=0,  ! normally 0 to initialise the model from a real atmosphere, but see ifs/module/yomdyncore.F90 for other possibilities.

Initialisation

 

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Please note that aqua-planet and other idealized configurations are a research tool and therefore may change between model versions.

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