[MITgcm-support] MITgcm-support Digest, Vol 126, Issue 13
Marco Reale
reale.marco82 at gmail.com
Wed Dec 4 16:44:21 EST 2013
Hi David,
and thanks a lot for your response: I followed your suggestion.
So finally the equation will be :
TOTUTEND/86400=Um_Advec+Um_diss+Um_HydroP;
each of these members of the equation are 4D arrays : following a point to check the balance at t = 30, level=12, i=9, j=30 and I got the following results:
TOTUTEND/86400= -8.0561e-10
Um_Advec= 2.5398e-07
Um_diss= 7.7003e-09
Um_HydroP=2.4196e-07
the balance of this term is 5.0365e-07
So I have done something wrong: I’m working with rough data without taking into account volume of cells, etc.
Any suggestions?
Marco
Il giorno 04/dic/2013, alle ore 11:54, mitgcm-support-request at mitgcm.org ha scritto:
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> Today's Topics:
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> 1. tracer sinks (Jan-Dirk Matthie?en)
> 2. Re: Balance of momentum (David Munday)
> 3. Re: tracer sinks (Martin Losch)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 04 Dec 2013 10:41:29 +0100
> From: Jan-Dirk Matthie?en <jMatthiessen at geomar.de>
> To: mitgcm-support at mitgcm.org
> Subject: [MITgcm-support] tracer sinks
> Message-ID: <529EF8C9.2090500 at geomar.de>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hello,
>
> I want to set up a model run with tracer sources and sinks.
> For now I used the Ptracer package to initialize the tracer and the rbcs
> package
> to make sources and sinks. But for my next experiment I need to have a
> concentration
> independent sink which I can not do with the rbcs package. I read in the
> manual that I should
> use the gchem package for sources and sinks, but I can't figure out how
> I have to set that up
> for only one tracer. Is there an easy solution for that or a
> verification experiment I missed where
> I can see how that works?
>
> Cheers,
> Jan-Dirk
>
> --
>
> Dipl.-Phys. Jan-Dirk Matthie?en
> Theorie und Modellierung
> GEOMAR
> Helmholtz-Zentrum f?r Ozeanforschung Kiel
> D?sternbrooker Weg 20, Raum: 55 Alte Botanik
> 24105 Kiel, Germany
>
> Tel. +49-431-600-4009
> Fax +49-431-600-4012
> jkohlmann at geomar.de
> www.geomar.de
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 4 Dec 2013 10:14:37 +0000
> From: David Munday <Munday at atm.ox.ac.uk>
> To: "<mitgcm-support at mitgcm.org>" <mitgcm-support at mitgcm.org>
> Subject: Re: [MITgcm-support] Balance of momentum
> Message-ID: <7B3679F5-F43F-4FDD-96DB-60D6127BC746 at atm.ox.ac.uk>
> Content-Type: text/plain; charset="windows-1252"
>
> Hi Marco,
>
> a) I saw from MITGCM manual that Um_Advec includes all the terms of acceleration including Coriolis, explicit diffusive terms , metric and pressure terms. So in my balance should I include only Um_Advec instead of Um_Advec+Um_Cori+Um_diss+Um_ext+Um_HydroP?
>
> Um_Advec includes Um_Cori, and any metric terms if you're using flux-form I guess. Um_diss, etc, aren't in Um_Advec and so you need to include them in your balance.
>
> As far as I'm aware, any explicit viscosity terms are also in Um_diss. I use implicit vertical viscosity, though, so I've never checked.
>
> b) I have the rigid -lid and so I should include in the balance also the term relative to Eta . How can I compute the contribution of Eta ? Is it simply dEta/dx = [Eta(i+1,j)-Eta(i,j)]/dxc(i,j)?or Should I consider to multiply this term for something else?In fact Eta with rigid lid is a pressure and so not an acceleration.Then It?s given on a single level: so should I sum this quantity to each level or dividing/multiplying it for something and then add to each level?
>
> Are you actually using a rigid lid? Or a linear free surface? Its only if you're using a linear free surface that I think you need to worry about this.
>
> I output the horizontal gradients of eta, really the gradient in surface potential, from momentum_correction_step.F. The quantities you need are calculated here and then used to update the U and V velocities. Just output phisurfX and phisurfY multiplied by -1 to get the sign right. They're 2D fields, but the same value applies at every vertical model level.
>
> Once you've got these gradients you should get an extremely well closed momentum budget by following the recipe in the chain of e-mails starting with Emily Shroyer's from December 2010, see http://mitgcm.org/pipermail/mitgcm-support/2010-December/thread.html#6918. These e-mails saved me a whole load of time when I wanted to close the momentum budget (thanks Emily, Matt, and Jean-Michel!)
>
> The signs coincide : the values appears to be different..what looks strange to me is also the sign because Uvel is positive.Did I something wrong in the computation? Did I forget some terms?Is it correct TOTUtend/86400?
>
> The sign of the tendency, total or otherwise, won't tell you the sign of U, just the sign of its change. See the e-mails linked above for what to add together. Yes, TOTUTEND should be divided by 86400 to get /s.
>
> Best wishes,
>
> Dave
>
> On 3 Dec 2013, at 23:08, Marco Reale wrote:
>
> Dear MITGCM users ,
>
> following the suggestion of Dr.Losch I posted a question about an analysis that I?m doing. I?m trying to compute a balance of vorticity for a basin : the first assessment (and verification) in this analysis is the computation of balance of momentum . Following a previous post in this mailing list I got during from my simulation the following diagnostics (I will talk only about U-component):
>
> Uvel,TOTUTEND,Um_Advec,Um_Cori,Um_diss,Um_ext,Um_HydroP,VISrE_Um (i?m using an explicit scheme).
>
>> From VISrE_Um I computed : Um_Expl(:,:,k) =[ VISrE_Um(:,:,k+1) - VISrE_Um(:,:,k) ] /[ rAw(:,:)*drF(k)*hFacW(:,:,k) ]
>
> My simulation have been run with rigid-lid , frequency for the diagnostics 432000 s , step of integration equal to 1200s , flux momentum formulation, 24 levels , 17 x 49 points for each levels, hydrostatic configuration.
>
> So following previous post the balance of momentum should be given for each level : TOTUTEND/86400=Um_Advec+Um_Cori+Um_diss+Um_ext+Um_HydroP+Um_Expl
>
> But :
>
> a) I saw from MITGCM manual that Um_Advec includes all the terms of acceleration including Coriolis, explicit diffusive terms , metric and pressure terms. So in my balance should I include only Um_Advec instead of Um_Advec+Um_Cori+Um_diss+Um_ext+Um_HydroP?
>
> b) I have the rigid -lid and so I should include in the balance also the term relative to Eta . How can I compute the contribution of Eta ? Is it simply dEta/dx = [Eta(i+1,j)-Eta(i,j)]/dxc(i,j)?or Should I consider to multiply this term for something else?In fact Eta with rigid lid is a pressure and so not an acceleration.Then It?s given on a single level: so should I sum this quantity to each level or dividing/multiplying it for something and then add to each level?
>
> Finally I considered a point in my domain in the first level and in the center of my domain at the time t=1 and I did the balance : TOTUtend/86400= Um_Advec+[Eta(i+1,j)-Eta(i,j)]/dxc(i,j)+Um_Expl and I got
>
> TOTUtend/86400=-1.02*10^-9
> Um_Advec+[Eta(i+1,j)-Eta(i,j)]/dxc(i,j)+Um_Expl=-1.50*10^-9
>
> The signs coincide : the values appears to be different..what looks strange to me is also the sign because Uvel is positive.Did I something wrong in the computation? Did I forget some terms?Is it correct TOTUtend/86400?
>
>
> Looking forward to a positive response to my question
>
>
> Best regards
>
>
> Marco
>
>
>
>
>
>
>
>
>
>
>
> ***********************************
> Marco Reale
> ph.D student "Environmental and Industrial Fluid Mechanics"-XXVII cycle
> University of Trieste-Department of Mathematics and Informatics
> National Institute of Geophysics and Oceanography (OGS)
> International Center for Theorethical Physics (ICTP)
> Italian Geophysical Association (AGI)
> Italian Meteorological Society (SMI)
> European Geophysical Union (EGU)
> web-page: http://phdfluidmechanics.appspot.com/stud.html?Reale
> skype: mcreal82
> phone number: +39 3270888069
>
> ***********************************
>
> _______________________________________________
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> *****************************************************************************
>
> Dr. David R. Munday
> University of Oxford
> Atmospheric, Oceanic, and Planetary Physics
> Clarendon Laboratory
> Parks Road
> Oxford
> OX1 3PU
> U.K. 01865 282 439
>
> *****************************************************************************
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> "But I, being poor, have only my dreams;
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> ------------------------------
>
> Message: 3
> Date: Wed, 4 Dec 2013 11:54:10 +0100
> From: Martin Losch <Martin.Losch at awi.de>
> To: MITgcm Support <mitgcm-support at mitgcm.org>
> Subject: Re: [MITgcm-support] tracer sinks
> Message-ID: <75B718E7-3168-4B72-B6BB-E3F71171C975 at awi.de>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Jan-Dirk,
>
> have a look at pkg/ptracers/ptracers_forcing.F (or for just a surface source ptracers_forcing_surf.F)
>
> Here you can add any source that you can compute on the fly.
>
> If you want to use the gchem package (which is basically an interface for different bgc-tracer models), you can do the same in gcham_calc_tendency.F.
>
> Martin
>
> On Dec 4, 2013, at 10:41 AM, Jan-Dirk Matthie?en <jMatthiessen at geomar.de> wrote:
>
>> Hello,
>>
>> I want to set up a model run with tracer sources and sinks.
>> For now I used the Ptracer package to initialize the tracer and the rbcs package
>> to make sources and sinks. But for my next experiment I need to have a concentration
>> independent sink which I can not do with the rbcs package. I read in the manual that I should
>> use the gchem package for sources and sinks, but I can't figure out how I have to set that up
>> for only one tracer. Is there an easy solution for that or a verification experiment I missed where
>> I can see how that works?
>>
>> Cheers,
>> Jan-Dirk
>>
>> --
>>
>> Dipl.-Phys. Jan-Dirk Matthie?en
>> Theorie und Modellierung
>> GEOMAR
>> Helmholtz-Zentrum f?r Ozeanforschung Kiel
>> D?sternbrooker Weg 20, Raum: 55 Alte Botanik
>> 24105 Kiel, Germany
>>
>> Tel. +49-431-600-4009
>> Fax +49-431-600-4012
>> jkohlmann at geomar.de
>> www.geomar.de
>>
>>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>
>
>
>
> ------------------------------
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support
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>
> End of MITgcm-support Digest, Vol 126, Issue 13
> ***********************************************
***********************************
Marco Reale
ph.D student "Environmental and Industrial Fluid Mechanics"-XXVII cycle
University of Trieste-Department of Mathematics and Informatics
National Institute of Geophysics and Oceanography (OGS)
International Center for Theorethical Physics (ICTP)
Italian Geophysical Association (AGI)
Italian Meteorological Society (SMI)
European Geophysical Union (EGU)
web-page: http://phdfluidmechanics.appspot.com/stud.html?Reale
skype: mcreal82
phone number: +39 3270888069
***********************************
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