[MITgcm-support] futureiter

Riema Rachmayani imoth_22 at yahoo.com
Wed Feb 14 22:39:48 EST 2007


hi, all
what the different between futureIter and futureTime??
futureIter =myiter*deltaT ?
futureTime=mytime*deltaT ?

any formula for cvelTimeScale in orlanski??

thank you,
-rima-



----- Original Message ----
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To: mitgcm-support at mitgcm.org
Sent: Thursday, February 15, 2007 12:00:06 AM
Subject: MITgcm-support Digest, Vol 44, Issue 8


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Today's Topics:

   1. advective fluxes and transports (Paola Cessi)
   2. Re: advective fluxes and transports (Baylor Fox-Kemper)
   3. Re: advective fluxes and transports (Dimitris Menemenlis)
   4. Re: advective fluxes and transports (Baylor Fox-Kemper)
   5. Re: advective fluxes and transports (Baylor Fox-Kemper)
   6. exf: river temperature? (Dmitri Leonov)
   7. Re: exf: river temperature? (Dimitris Menemenlis)
   8. Re: exf: river temperature? (Jean-Michel Campin)


----------------------------------------------------------------------

Message: 1
Date: Tue, 13 Feb 2007 10:02:20 -0800 (PST)
From: Paola Cessi <pcessi at ucsd.edu>
Subject: [MITgcm-support] advective fluxes and transports
To: mitgcm-support at mitgcm.org
Message-ID: <Pine.LNX.4.60.0702130958280.7967 at the.ucsd.edu>
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed

What, if any, is the difference between the triplet of diagnostics 
(UVELTH,VVELTH,WVELTH) and (ADVx_TH,ADVy_TH,ADVr_TH) for a Boussinesq 
case, using flux-limited schemes?

Thank you,

Paola

-------------------------------------------------------------------------
Paola Cessi                            Tel: +1 858 534 0622
Scripps Institution of Oceanography    Fax: +1 858 534 8045
9500 Gilman Drive #0213                e-mail: pcessi at ucsd.edu
La Jolla, CA 92093-0213
USA                      Web:  http://www-pord.ucsd.edu/~pcessi



------------------------------

Message: 2
Date: Tue, 13 Feb 2007 14:32:15 -0500
From: Baylor Fox-Kemper <baylor at MIT.EDU>
Subject: Re: [MITgcm-support] advective fluxes and transports
To: mitgcm-support at mitgcm.org
Message-ID: <8035603D-773F-46D5-8B7A-70C66F6E00A2 at mit.edu>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

Hi Paola,
  UVELTH is just the correlation of the U and theta fields, with  
temperature appropriate interpolated.  ADVx_TH is the advective flux,  
which can include things like the variable grid box size with  
nonlinear free surface, shaved cells, etc, as well as the flux- 
limiting corrections.  UVELTH will be equivalent to ADVx_TH only with  
centered 2nd-order advection and simple vertical discretization/ 
boundary conditions.
   Cheers,
    -Baylor

On Feb 13, 2007, at 1:02 PM, Paola Cessi wrote:

> What, if any, is the difference between the triplet of diagnostics  
> (UVELTH,VVELTH,WVELTH) and (ADVx_TH,ADVy_TH,ADVr_TH) for a  
> Boussinesq case, using flux-limited schemes?
>
> Thank you,
>
> Paola
>
> ---------------------------------------------------------------------- 
> ---
> Paola Cessi                            Tel: +1 858 534 0622
> Scripps Institution of Oceanography    Fax: +1 858 534 8045
> 9500 Gilman Drive #0213                e-mail: pcessi at ucsd.edu
> La Jolla, CA 92093-0213
> USA                      Web:  http://www-pord.ucsd.edu/~pcessi
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support



------------------------------

Message: 3
Date: Tue, 13 Feb 2007 11:44:27 -0800
From: Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
Subject: Re: [MITgcm-support] advective fluxes and transports
To: mitgcm-support at mitgcm.org
Message-ID: <45D2151B.2020204 at jpl.nasa.gov>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Baylor, for computation of transports, which diagnostic should one use: ADVx_TH, 
UTHMASS, or UVELTH?  To date I have been using UTHMASS but from your description 
below it sounds like it would be more accurate to use ADVx_TH ?  D.


> Hi Paola, UVELTH is just the correlation of the U and theta fields, with
> temperature appropriate interpolated.  ADVx_TH is the advective flux, which
> can include things like the variable grid box size with nonlinear free
> surface, shaved cells, etc, as well as the flux-limiting corrections.  UVELTH
> will be equivalent to ADVx_TH only with centered 2nd-order advection and
> simple vertical discretization/boundary conditions. Cheers, -Baylor


-- 
Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
Jet Propulsion Lab, California Institute of Technology
MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
tel: 818-354-1656;  fax: 818-393-6720


------------------------------

Message: 4
Date: Tue, 13 Feb 2007 15:18:37 -0500
From: Baylor Fox-Kemper <baylor at MIT.EDU>
Subject: Re: [MITgcm-support] advective fluxes and transports
To: mitgcm-support at mitgcm.org
Message-ID: <BBDFF6AE-6B6B-41C2-A1CD-0D8C336201BA at mit.edu>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

Hi Dimitris (and Paola),
   A bit more:
1) UVELTH is just the correlation between U and T.
2) UTHMASS is the correlation between U and T, weighted by 'mass', or  
HFac, which gives free-surface corrections.
3) ADVx_TH is the 'effect of advection'.  It includes flux-limiting  
and diffusion from the numerical scheme.

So,
1) for statistics, UVELTH is probably best, because other  
complexities are just messing things up.
2) for transports that are 'advective', i.e., no explicit or overt  
implicit diffusive fluxes UTHMASS is good.
3) for closing budgets, or for diagnosing the full effect of the  
advection operator (which is, when flux-limiting, partly 'diffusive'  
in nature) use ADVx_TH.  You will not, for example, be able to easily  
account for all the terms leading to dT/dt at a given gridcell unless  
you use ADVx_TH.

If you really want to get fancy, you could save all three and see  
what the differences are... This allows you to break things down  
into, e.g., Stokes drift at the surface due to free surface effects  
(UVELTH vs UTHMASS), or how much of ADVx_TH is 'diffusive' versus  
'advective'.
    -Baylor

P.S. Keep in mind that second-order centered is not totally without  
'diffusive' discretization errors, just that no effort is made to  
exploit the diffusive errors to our advantage.  The discretization  
errors in second order centered appear as a hyperdiffusion: \nabla^4  
T.  Fourth-order centered is less 'diffusive', with discretization  
errors appearing only at \nabla^6 T.

Upwinding and flux-limiting exploit the fact that errors can be  
steered toward monotonicity and stability by messing around with  
diffusive errors at the cost of lower order accuracy. So, for  
example, first order upwinding can be thought of as adding an  
automatic \nabla^2 T diffusion to a second-ordered centered scheme.   
Third-order upwinding can be thought of as adding an automatic  
\nabla^4 T hyperdiffusion to a fourth-order centered scheme, etc.   
But, the amount of diffusivity added is dependent on velocity, e.g.,  
the "effective kappa" added is proportional gridscale*|U| in the  
first-order upwind versus second-order centered.  Thus, it is hard to  
diagnose after the fact.  Comparing ADVx and UTHMASS allows one to  
quickly do so.

On Feb 13, 2007, at 2:44 PM, Dimitris Menemenlis wrote:

> Baylor, for computation of transports, which diagnostic should one  
> use: ADVx_TH, UTHMASS, or UVELTH?  To date I have been using  
> UTHMASS but from your description below it sounds like it would be  
> more accurate to use ADVx_TH ?  D.
>
>
>> Hi Paola, UVELTH is just the correlation of the U and theta  
>> fields, with
>> temperature appropriate interpolated.  ADVx_TH is the advective  
>> flux, which
>> can include things like the variable grid box size with nonlinear  
>> free
>> surface, shaved cells, etc, as well as the flux-limiting  
>> corrections.  UVELTH
>> will be equivalent to ADVx_TH only with centered 2nd-order  
>> advection and
>> simple vertical discretization/boundary conditions. Cheers, -Baylor
>
>
> -- 
> Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
> Jet Propulsion Lab, California Institute of Technology
> MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
> tel: 818-354-1656;  fax: 818-393-6720
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support



------------------------------

Message: 5
Date: Tue, 13 Feb 2007 15:40:36 -0500
From: Baylor Fox-Kemper <baylor at MIT.EDU>
Subject: Re: [MITgcm-support] advective fluxes and transports
To: mitgcm-support at mitgcm.org
Message-ID: <52D55129-E3BE-45F8-8A8F-56A9C0F12053 at mit.edu>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

Small correction:
> P.S. Keep in mind that second-order centered is not totally without  
> 'diffusive' discretization errors, just that no effort is made to  
> exploit the diffusive errors to our advantage.  The discretization  
> errors in second order centered appear as a hyperdiffusion:  
> \nabla^4 T.  Fourth-order centered is less 'diffusive', with  
> discretization errors appearing only at \nabla^6 T.
This should say the 'diffusive' discretization errors in second order  
centered appear as a hyperdiffusion: \nabla^4 T.  Fourth-order  
centered is less 'diffusive', with 'diffusive' discretization errors  
appearing only at \nabla^6 T.

There are also dispersive advection errors appearing at \nabla^3 T   
and \nabla^5 levels respectively...

>
> Upwinding and flux-limiting exploit the fact that errors can be  
> steered toward monotonicity and stability by messing around with  
> diffusive errors at the cost of lower order accuracy. So, for  
> example, first order upwinding can be thought of as adding an  
> automatic \nabla^2 T diffusion to a second-ordered centered  
> scheme.  Third-order upwinding can be thought of as adding an  
> automatic \nabla^4 T hyperdiffusion to a fourth-order centered  
> scheme, etc.  But, the amount of diffusivity added is dependent on  
> velocity, e.g., the "effective kappa" added is proportional  
> gridscale*|U| in the first-order upwind versus second-order  
> centered.  Thus, it is hard to diagnose after the fact.  Comparing  
> ADVx and UTHMASS allows one to quickly do so.
>
> On Feb 13, 2007, at 2:44 PM, Dimitris Menemenlis wrote:
>
>> Baylor, for computation of transports, which diagnostic should one  
>> use: ADVx_TH, UTHMASS, or UVELTH?  To date I have been using  
>> UTHMASS but from your description below it sounds like it would be  
>> more accurate to use ADVx_TH ?  D.
>>
>>
>>> Hi Paola, UVELTH is just the correlation of the U and theta  
>>> fields, with
>>> temperature appropriate interpolated.  ADVx_TH is the advective  
>>> flux, which
>>> can include things like the variable grid box size with nonlinear  
>>> free
>>> surface, shaved cells, etc, as well as the flux-limiting  
>>> corrections.  UVELTH
>>> will be equivalent to ADVx_TH only with centered 2nd-order  
>>> advection and
>>> simple vertical discretization/boundary conditions. Cheers, -Baylor
>>
>>
>> -- 
>> Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
>> Jet Propulsion Lab, California Institute of Technology
>> MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
>> tel: 818-354-1656;  fax: 818-393-6720
>> _______________________________________________
>> 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



------------------------------

Message: 6
Date: Tue, 13 Feb 2007 14:55:43 -0800
From: Dmitri Leonov <dleonov at u.washington.edu>
Subject: [MITgcm-support] exf: river temperature?
To: mitgcm-support at mitgcm.org
Message-ID: <45D241EF.90603 at u.washington.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hello,

I'm using exf package to specify river runoff. What would be the easiest 
way to account for a time-dependent river temperature? 
I'd prefer not to use an open boundary. If I use hflux* parameters, will 
I be able to add bulk formulae to that for atmospheric forcing?

I'd appreciate any suggestions.
Thanks.

Dmitri

------------------------------------------------
Dmitri A. Leonov
Research Associate, Postdoctoral
University of Washington, School of Oceanography




------------------------------

Message: 7
Date: Tue, 13 Feb 2007 17:59:12 -0800
From: Dimitris Menemenlis <menemenlis at sbcglobal.net>
Subject: Re: [MITgcm-support] exf: river temperature?
To: mitgcm-support at mitgcm.org
Message-ID: <45D26CF0.8000701 at sbcglobal.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

> I'm using exf package to specify river runoff. What would be the easiest way
> to account for a time-dependent river temperature? I'd prefer not to use an
> open boundary. If I use hflux* parameters, will I be able to add bulk
> formulae to that for atmospheric forcing?

If you want to use bulk formulae, maybe you could add the flux
to long-wave radiation, lwdown or lwflux, instead?



------------------------------

Message: 8
Date: Tue, 13 Feb 2007 21:00:15 -0500
From: Jean-Michel Campin <jmc at ocean.mit.edu>
Subject: Re: [MITgcm-support] exf: river temperature?
To: mitgcm-support at mitgcm.org
Message-ID: <20070214020015.GA20031 at ocean.mit.edu>
Content-Type: text/plain; charset=us-ascii

Hi Dimitri.

When I run a coupled set-up, time dependent river temperature
is accounted for by using, for the ocean:
exactConserv=.TRUE.,
select_rStar=2,
nonlinFreeSurf=4,
useRealFreshWaterFlux=.TRUE.,
temp_EvPrRn=0.,
(see MITgcm/verification/cpl_aim+ocn/input_ocn/data)
And in addition, in the atmospheric model, the heat content of EmPmR 
is added separately to the net surface heat flux. 

Regarding an ocean only set-up (using, e.g., EXF package), 
I don't remember of a specific entry for this heat flux in the EXF 
package. May be the simplest thing to do would be to add this heat 
flux contribution to one of the fixed EXF forcing fields (and files).

Jean-Michel

On Tue, Feb 13, 2007 at 02:55:43PM -0800, Dmitri Leonov wrote:
> Hello,
> 
> I'm using exf package to specify river runoff. What would be the easiest 
> way to account for a time-dependent river temperature? 
> I'd prefer not to use an open boundary. If I use hflux* parameters, will 
> I be able to add bulk formulae to that for atmospheric forcing?
> 
> I'd appreciate any suggestions.
> Thanks.
> 
> Dmitri
> 
> ------------------------------------------------
> Dmitri A. Leonov
> Research Associate, Postdoctoral
> University of Washington, School of Oceanography
> 
> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support


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