[MITgcm-support] MITgcm-support Digest, Vol 119, Issue 11
Olivier Arzel
Olivier.Arzel at univ-brest.fr
Wed May 22 09:02:31 EDT 2013
Hi Jean-Michel,
Thank you very much. The logical parameter linFSConserveTr=.TRUE. has
solved the issue.
Setting allowFreezing=.FALSE. did not change anything since temperature
remain above zero in my experiment.
Cheers,
Olivier
Le 21/05/2013 18:00, mitgcm-support-request at mitgcm.org a écrit :
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> Today's Topics:
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> 1. Using exch2 tiling to force symmetry (Jason Goodman)
> 2. Re: flux boundary condition (Jean-Michel Campin)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Mon, 20 May 2013 18:24:34 -0400
> From: Jason Goodman <goodman_jason at wheatoncollege.edu>
> To: "mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
> Subject: [MITgcm-support] Using exch2 tiling to force symmetry
> Message-ID: <EFA72FE2-37AC-4139-9725-19315DC70F90 at wheatoncollege.edu>
> Content-Type: text/plain; charset=us-ascii
>
> I'm performing a zonally and meridionally symmetric cubed-sphere run on a water world. It seems wasteful to model both the northern and southern hemispheres, since they'll look the same, but I want to make sure there's no wall at the equator that could disrupt the flow.
>
> Is it possible to use exch2 tiling to implement "mirror" boundary conditions across the equator of a cubed hemisphere? So that, for example, the neighbor of a tile bordering the equator is the tile itself, just flipped upside down?
>
> Is this even worth my time? Is there a better way?
>
> Jason Goodman
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 21 May 2013 08:21:02 -0400
> From: Jean-Michel Campin <jmc at ocean.mit.edu>
> To: mitgcm-support at mitgcm.org
> Subject: Re: [MITgcm-support] flux boundary condition
> Message-ID: <20130521122102.GA18485 at ocean.mit.edu>
> Content-Type: text/plain; charset=iso-8859-1
>
> Hi Oliver,
>
> I don't expect the model to conserve heat when using:
>> allowFreezing=.TRUE.,
> that put back to -1.9 any surface temp that fall below.
> You can diagnose how much heating this "allowFreezing" implies
> by looking at the diagnostic 'oceFreez'
>
> I suspect that if you try with allowFreezing=.FALSE., the global
> mean temp will drift much less. There is still an other source
> of non-conservation related to linear free-surface (I think it's
> mentioned in the 2004 ocean Modelling paper "Conservation of
> properties in a free surface model").
> The global average of this source is output in the monitor: "surfExpan_theta_mean"
> (but in your case, this term seems small to me, and very stable ?)
> and can be corrected for by turning on the logical flag:
>> linFSConserveTr=.TRUE.,
> (main parameter file "data", 1rst namelist "PARM01").
>
> Cheers,
> Jean-Michel
>
> On Mon, May 20, 2013 at 01:10:38PM +0200, Olivier Arzel wrote:
>> Hello all,
>> I am running an experiment under constant flux boundary conditions
>> for temperature and salinity.
>> While I have a zero net surface heat flux in average, there is a
>> trend in the global average ocean temperature.
>> I must have missed something obvious here but I cannot figure it out.
>> Attached are the data file and the timeseries of the statistics that
>> show zero FORCING_QNET_MEAN and a temperature trend in
>> DYNSTAT_THETA_MEAN.
>> To reach zero average surface heat flux, here is what I did using matlab:
>> areasum=sum(sum(grid_ocn.HFacC(:,:,1).*grid_ocn.rA));
>> varmean=sum(sum(shf_rtrs.*grid_ocn.HFacC(:,:,1).*grid_ocn.rA))/areasum;
>> shf_rtrs=shf_rtrs-varmean*grid_ocn.HFacC(:,:,1);
>> % mean shf_rtrs is zero
>> I did the same for salinity forcing, and observe no salinity trend,
>> perhaps due to the fact that I use exactConserv=.TRUE. ?
>> Any help would be much appreciated
>> Thanks !
>> Olivier
>>
>>
>> --
>> -----------------------------------
>> Olivier Arzel
>> Laboratoire de Physique des Oc?ans
>> Universit? de Bretagne Occidentale
>> 6 Avenue le Gorgeu / CS 93837
>> 29238 Brest cedex 3
>> France
>> Tel: +33 (0)2 98 01 62 25
>> Fax: +33 (0)2 98 01 64 68
>> homepage : http://stockage.univ-brest.fr/~oarzel/
>> homepage : http://web.maths.unsw.edu.au/~oarzel/
>>
>> -----------------------------------
>>
>> # ====================
>> # | Model parameters |
>> # ====================
>> #
>> # Continuous equation parameters
>> &PARM01
>> tRef = 32*4.,
>> sRef = 32*35.,
>> viscAr=1.E-3,
>> viscAh=1.E5,
>> diffKhT=0.,
>> diffKrT=1.E-4,
>> diffKhS=0.,
>> diffKrS=1.E-4,
>> rhonil=1035.,
>> rhoConstFresh=1000.,
>> tAlpha=2.E-4,
>> sBeta =8.E-4,
>> eosType = 'LINEAR',
>> ivdc_kappa=100.,
>> implicitDiffusion=.TRUE.,
>> allowFreezing=.TRUE.,
>> exactConserv=.TRUE.,
>> useRealFreshWaterFlux=.TRUE.,
>> useCDscheme=.TRUE.,
>> # turn on looped cells
>> hFacMin=.05,
>> hFacMindr=50.,
>> # set precision of data files
>> readBinaryPrec=64,
>> &
>>
>> # Elliptic solver parameters
>> &PARM02
>> cg2dMaxIters=500,
>> cg2dTargetResidual=1.E-13,
>> &
>>
>> # Time stepping parameters
>> &PARM03
>> # nIter0= 0,
>> # nTimeSteps = 20,
>> startTime = 0.,
>> endTime = 155520000000,
>> deltaTmom = 300.,
>> tauCD = 321428.,
>> deltaTtracer= 86400.,
>> deltaTClock = 86400.,
>> deltaTfreesurf= 86400.,
>> abEps = 0.1,
>> pChkptFreq= 31104000000.,
>> dumpFreq= 3110400000.,
>> taveFreq= 3110400000.,
>> monitorFreq=31104000.,
>> # 2 months restoring timescale for temperature
>> # tauThetaClimRelax= 5184000.,
>> # 6 months restoring timescale for salinity
>> # tauSaltClimRelax = 15552000.,
>> # periodicExternalForcing=.FALSE.,
>> # externForcingPeriod=2592000.,
>> # externForcingCycle=31104000.,
>> &
>>
>> # Gridding parameters
>> &PARM04
>> usingSphericalPolarGrid=.TRUE.,
>> delR= 15., 32., 41., 50., 59., 68., 77., 86.,
>> 95., 104., 113., 122., 131., 140., 149., 158.,
>> 167., 176., 185., 194., 203., 212., 221., 230.,
>> 239., 248., 257., 266., 275., 285., 296., 306.,
>> ygOrigin=-70.,
>> dySpacing=1.,
>> dxSpacing=1.,
>> &
>>
>> # Input datasets
>> &PARM05
>> bathyFile= 'bathymetry.bin',
>> hydrogThetaFile=,
>> hydrogSaltFile= ,
>> zonalWindFile= 'windx.bin',
>> meridWindFile= ,
>> thetaClimFile= ,
>> saltClimFile= ,
>> surfQnetFile= 'shf_rtrs.bin',
>> the_run_name= 'idealized_atl',
>> # fresh water flux is turned on, comment next line to it turn off
>> # (maybe better with surface salinity restoring)
>> EmPmRFile= 'emp_rtrs.bin',
>> &
>
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> End of MITgcm-support Digest, Vol 119, Issue 11
> ***********************************************
>
--
-----------------------------------
Olivier Arzel
Laboratoire de Physique des Océans
Université de Bretagne Occidentale
6 Avenue le Gorgeu / CS 93837
29238 Brest cedex 3
France
Tel: +33 (0)2 98 01 62 25
Fax: +33 (0)2 98 01 64 68
homepage : http://stockage.univ-brest.fr/~oarzel/
homepage : http://web.maths.unsw.edu.au/~oarzel/
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