[MITgcm-devel] [Fwd: Re: ECCO numerics]

[Patrick Heimbach]

Dimitris,

not aware what this bug whould be.
Are the more specifics?
(even just a difference btw. old and corrected code would
be helpful to compare with our implementation).

I ran a 13-yr cost diagnostic between L&P82 and L&Y04
1/2 year ago, and the differences where almost unnoticeable.
Essentially, the "bulk formulae" themselves are identical
(which I distinguish from "radiation").
The major differences come from the recommendations
for radiation parameters to be used, i.e. for
albedo and for emissivity.

-Patrick



On Aug 7, 2007, at 10:39 AM, Dimitris Menemenlis wrote:

> All, is anyone aware of bug mentioned below?
> Is it already fixed in pkg/exf/exf_bulk_largeyeager04.F
> Also, I have been using Large & Pond 1981 for all the CS510  
> integrations.
> Should I switch to Large & Yeager 2004?
> I seem to recollect that someone had verified that the
> two formulations were identical?
>
> Dimitris
>
>
> -------- Original Message --------
> Subject: Re: ECCO numerics
> Date: Tue, 07 Aug 2007 10:23:39 -0400
> From: Stephen Griffies <Stephen.Griffies at noaa.gov>
> To: Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
> CC: Alistair Adcroft <Alistair.Adcroft at noaa.gov>
>
> Hi,
>
> Thanks for the feedback. Very interesting...
>
> One (pesky) thing to note is that just a few weeks ago, a French  
> student
> discovered a (perhaps minor) bug in the bulk formulae code used for  
> the
> CORE forcing.  This bug affects the ce and ch heat exchange
> coefficients.  I do not know if the bug would affect your CORE runs
> much, but something to consider for future runs is an update to this
> code (assuming you downloaded it from GFDL).
>
> Go to
>
> http://data1.gfdl.noaa.gov/nomads/forms/mom4/CORE/code.html
>
> and update the code in ncar_ocean_fluxes.f90
>
> Steve
>
>
>
> Dimitris Menemenlis wrote:
>> Steve, thank you for helpful feedback.
>> Yesterday I looked at the first overall comparisons of 18-km cubed- 
>> sphere integrations with and without GM-Redi versus global  
>> temperature and salinity profiles from XBT, CTD, TAO moorings, and  
>> ARGO floats and your reservations regarding use of GM-Redi at this  
>> resolution are justified.  Overall three 1992-2002 integrations  
>> with GM-Redi do slightly worse than a baseline integration without  
>> GM-Redi.  I still need to examine the solutions in more detail  
>> though, especially in Mode water formation region, to figure out  
>> what happened.
>> You are also right about tunable parameters for GM-Redi: there are  
>> way too many, especially when you add tapering so I was a bit at a  
>> loss what to choose.
>> For 10-m wind forcing we have tried NCEP reanalysis, Large and  
>> Yeager's CORE, which you provided (thanks!), ERA40 followed by  
>> ECMWF analysis after August 2002, and some winds estimated from a  
>> coarse-resolution adjoint-method optimization.
>> Another motivation for turning on GM-Redi is that OS7MP solution,  
>> even though spectacularly better in places, e.g., the Arctic  
>> Ocean, creates regions that are marginally stable and where grid- 
>> scale noise appears.  An integration forced by ECMWF analysis and  
>> without GM-Redi blew up in June 2004 (for a reason that I have not  
>> yet diagnosed) and I am reluctant to lower time step or to add  
>> horizontal diffusivity, hence the experiments with GM-Redi.
>> Dimitris
>
>
>
> -- 
> 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; cell: 818-625-6498; fax: 818-393-6720
> _______________________________________________
> MITgcm-devel mailing list
> MITgcm-devel at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-devel

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