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The aqua-planet

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 general publications on aqua-planet simulations:

  • 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.


Info

Please note that the 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.



 

 

 
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Expand
titleExpand to see required code changes...

The required code changes are small.

In the file: src/ifs/phys_ec/gp_sstaqua.F90, find the lines 233:238:

Code Block
        ! 3KW1
        RCHI=3.0_JPRB
        IF( ABS(PGEMU(IOFF+JROF-1)) <= SIN(RPHID) ) THEN
          PSD_VF(JROF,YSD_VF%YSST%MP,IBL)=PSD_VF(JROF,YSD_VF%YSST%MP,IBL)+&
           &RCHI*COS(PGELAM(IOFF+JROF-1)-RLAMBDA0)*&
           &COS(0.5_JPRB*ZPI*(ASIN(PGEMU(IOFF+JROF-1))/RPHID))**2

The use of RPHID needs to be corrected to 60o:

Code Block
        ! 3KW1
        RCHI=3.0_JPRB
        IF( ABS(PGEMU(IOFF+JROF-1)) <= SIN(2._JPRB*RPHID) ) THEN                   !  correct use of RPHID on this line
          PSD_VF(JROF,YSD_VF%YSST%MP,IBL)=PSD_VF(JROF,YSD_VF%YSST%MP,IBL)+&
           &RCHI*COS(PGELAM(IOFF+JROF-1)-RLAMBDA0)*&
           &COS(0.5_JPRB*ZPI*(ASIN(PGEMU(IOFF+JROF-1))/(2._JPRB*RPHID)))**2        !  correct use of RPHID on this line

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Configuration
Configuring OpenIFS for an aqua-planet simulation requires appropriate changes to:
...
 Expand
titleFor aqua-planet NAEPHY namelist, click here to expand...

 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 version 38r1).
LWCOU2W=false,   ! turn on/off two-way interaction with the wave model (n.b. always off for OpenIFS model version 38r1).
/
 


Initialisation
OpenIFS (and IFS) can be initialized either with real fields or idealized starting conditions.This is controlled both by the namelist switch N3DINI and by the code in the model.
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There are two ways in which this can be achieved; either take an existing set of model initial files (the ICM*INI* files) and interpolate 
 
pressure to the surface, or run the model and adjust the orography and pressure whilst the model is running to prevent a sudden 'shock'.

Also see
ECMWF took part in the 2012 Dynamical Core Model Intercomparison Project (DCMIP). More information can be found here: https://www.earthsystemcog.org/projects/dcmip-2012/
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OpenIFS would like to thank Sylvie Malardel (ECMWF) and Peter Bechtold (ECMWF) for their assistance in preparing this material
Related articles
 Content by LabelshowLabelsfalsemax5spacesOIFSshowSpacefalsesortmodifiedreversetruetypepagecqllabel in ("openifs","aqua-planet") and type = "page" and space = "OIFS"labelsopenifs aqua-planet
 


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Credits
Credits
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