[MITgcm-support] [SPAM] Re: [SPAM] Re: [SPAM] Re: FW: Diagnose momentum equation
Jean-Michel Campin
jmc at ocean.mit.edu
Tue Oct 6 14:37:44 EDT 2015
Hi Lianzhan,
> One more thing, does "U/Vm_Advec" also include "U/Vm_Cori" in flux-form momentum equation ?
Yes, "U/Vm_Advec" also includes "U/Vm_Cori" in flux-form ; the only exception
is if you were using the CD-scheme (and the reason is related to time-stepping
option of CD-scheme part).
Cheers,
Jean-Michel
On Sun, Oct 04, 2015 at 03:03:12PM +0800, lianzhan at fio.org.cn wrote:
> Hi Jean-Michel???
>
> Thank you so much for your help, your comments are really helpful.
> One more thing, does "U/Vm_Advec" also include "U/Vm_Cori" in flux-form momentum equation ?
> Cheers
> Lianzhan
>
> From: Jean-Michel Campin
> Date: 2015-10-01 05:57
> To: mitgcm-support
> Subject: [SPAM] Re: [MITgcm-support] [SPAM] Re: [SPAM] Re: FW: Diagnose momentum equation
> Hi Lianzhan,
>
> Few comments here:
> 1) One thing that I woud suggest to try is to also output the statistics of
> the same diagnostics you already output in 3-D.
> It's easy to do from the 2nd namelist "DIAG_STATIS_PARMS" in file "data.diagnostics",
> e.g.:
> &DIAG_STATIS_PARMS
> diagSt_mnc = .FALSE.,
> #--
> stat_fields(1:13,1) = 'ETAN ','THETA ','SALT ',
> 'UVEL ','VVEL ','WVEL ',
> 'Um_Advec','Um_Cori ','Um_dPHdx',
> 'Vm_Advec','Vm_Cori ','Vm_dPHdy',
> 'Um_AdvRe',
> stat_fName(1) = 'dynStDiag',
> stat_freq(1) = -86400.,
> stat_phase(1) = 0.,
> &
> and this will produce an ASCII file with the per level statistics
> and global staticstics (min,max,mean and standard-deviation) for
> each of the stat_fields in the list.
>
> Since these stats are computed from the same place as the 3-D diagnostics
> are filled up, it's a simple & quick way to check:
> 1) if a diagnostics is really filled up ; if not, a warning message
> is printed and the "Volume" column indicates "0."
> For instance here this will happen with diagnostics "Um_AdvRe"
> which is specific to pkg/mom_vecinv, not used in your case (the
> default is to use pkg/mom_fluxform)
> 2) which levels are filled up (by checking the "Volume" column)
> 3) the precise min/max for each level.
>
> 2) I noticed in your "data" file:
> tRef=20.,
> but since Nr > 1, it would be safer to specify something like:
> tRef=31*20.,
> (assuming Nr=31)
>
> 3) regarding some momentum diagnostics:
> a) there is no specific diagnostics for "-gravity * Grad( SSH )" term
> since it's a linear term (time-mean of gradient = gradient of mean SSH)
> which can easily be computed from SSH output (Eta).
> b) "U/Vm_Advec" does include the Coriolis acceleration (U/Vm_Cori)
> (except if using the CD-scheme): the reason is that in vector-invariant,
> advection and coriolis can be (partly) combined.
> c) some momentum diagnostics are specific to one momumtum formulation, e.g.:
> only in vector-invariant: Um_AdvRe, Um_AdvZ3
> only in flux-form: ADVx_Um, ADVy_Um, ADVrE_Um
>
> Cheers,
> Jean-Michel
>
> On Tue, Sep 29, 2015 at 08:28:49AM +0800, lianzhan at fio.org.cn wrote:
> > Hi Jean-Michel
> >
> > I am sorry, maybe you can find the attachments this time.
> >
> > In this set-up, the barotropic model is driving by wind stress on sea surface.
> >
> > Thanks again.
> >
> > Cheers
> >
> > Lianzhan
> >
> > From: Jean-Michel Campin
> > Date: 2015-09-29 01:57
> > To: mitgcm-support
> > Subject: [SPAM] Re: [MITgcm-support] [SPAM] Re: FW: Diagnose momentum equation
> > Hi Lianzhan,
> >
> > Two quick things:
> > 1)
> > > The attachements are "data" and "dada.pkg" files of my exp.
> > I did not find these attached files. Are you sure you really included them ?
> >
> > 2)
> > > What type of forcing do you have in this set-up ?
> > An answer to this question would be useful.
> >
> > Cheers,
> > Jean-Michel
> >
> > On Mon, Sep 28, 2015 at 05:44:07PM +0800, lianzhan at fio.org.cn wrote:
> > > Hi Jean-Michel:
> > >
> > > Thank you so much for your help!
> > >
> > > The attachements are "data" and "dada.pkg" files of my exp.
> > >
> > > About U/Vm_dPHdx, I think you are right. But in this exp, I have used Non-linear free-surface and apply free surface effect to column total thickness (implicSurfPress = 0.5 & nonlinFreeSurf=4 ...). So how could I output the pressure anomaly horizontal gradient caused by the fluctuation on sea surface?
> > >
> > > I am still trying to figure out what happen with U/Vm_Cor and U/Vm_Advec. Does "U/Vm_Advec" respresent the "UdU/dx+VdU/dy+WdU/dz" term in momentum equation? What is the different between "U/Vm_Advec" and "U/Vm_AdvZ3"?
> > >
> > > Thanks again!
> > >
> > > Cheers
> > >
> > > Lianzhan
> > >
> > >
> > > From: Jean-Michel Campin
> > > Date: 2015-09-26 23:19
> > > To: mitgcm-support
> > > Subject: [SPAM] Re: [MITgcm-support] FW: Diagnose momentum equation
> > > Hi Lianzhan,
> > >
> > > It's likely that if Temp & Salt remains uniform, U/Vm_dPHdx will be zero
> > > (no hydrostatic pressure anomaly horizontal gradient).
> > > Not very clear why U/Vm_Cori would be zero everywhere except for surface level,
> > > unless the velocity (uVel,vVel) is also zero everywhere below k=1.
> > >
> > > What type of forcing do you have in this set-up ?
> > >
> > > If you could send (in attachement) the 2 parameter files "data" and
> > > "data.pkg", this would help to figure out what is happening.
> > >
> > > Cheers,
> > > Jean-Michel
> > >
> > > On Sat, Sep 26, 2015 at 01:27:27PM +0000, lianzhan wrote:
> > > > Hello everyone
> > > >
> > > > I want to diagnose the effect of all items in momentum equation (as below for zonal).
> > > > dU/dt+UdU/dx+VdU/dy+WdU/dz=fv-1/rho*dP/dx+Fx+taux/rho
> > > > Fx is dissipative stress, taux is wind stress. Is there any corresponding variable in pkg/diagnostics ? I have tried "U/Vm_Advec" for nonlinear term, but this variable is zero expect for the surface layer. Its value is as same as "U/Vm_Cori", the value of "U/Vm_Cori" is also zero below surface. And "U/Vm_dPHdx"(pressure gradient force ? ) is all zero.
> > > > The settings of my exp is that there is an island located in an ideal rectangular bay, near which there is a sill. The model has 32 vertical layers and with free surface. The Temp/Salt is uniform.
> > > > Do you have any recommendations or suggestions?
> > > > Thanks in advance for your helpCheers,Lianzhan
> > > >
> > > >
> > > > xiaober at outlook.com
> > > >
> > > >
> > >
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