[ecco-support] Budgets in ECv4, release 3

Sat Nov 4 21:39:33 EDT 2017

Hi Ou,
It may be possible to close the budgets for the global ocean with single
precision output, but this is not the case for regional budgets.  For these
we really do need to have double precision outputs. Attached are a couple
of plots that show this.

I am looking at mass and heat budgets over the top 1000m. What I did was
take the r3/iter3 output, which has double precision, and after loading
each file (e.g., UVELMASS, etc.), I converted to single precision (the back
to double so the gcmfaces programs work). When I use the double precision
output, (tend-ocean convergence - forcing)./ tend < 1e-7 for both mass and
heat (see budgetM1000m_errorDouble.eps and budgetHC1000m_errorDouble.eps).
However, when the outputs are converted to single precision the errors are
much, much larger, (see budgetM1000m_errorSingle.eps and
budgetHC1000m_errorSingle.eps).

One of the touted advantages of ECCO is the ability to do budgets, so we
need outputs that allow us to do budget over any arbitrary regions, not
just simple ones, like the global average. So can we get the new outputs in
double precision please?!
thanks,
Martha

On Thu, Nov 2, 2017 at 1:54 PM, Wang, Ou (329B) <Ou.Wang at jpl.nasa.gov>
wrote:

> Hi Martha,
>
> I am also able to close the heat budget for the top ~1000m of the global
> ocean.
>
> Regards,
> Ou
>
> From: <ecco-support-bounces at mit.edu> on behalf of Martha Buckley <
> marthabuckley at gmail.com>
> Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu>
> Date: Thursday, November 2, 2017 at 10:11 AM
>
> To: "ECCO support list, wider membership" <ecco-support at mit.edu>
> Subject: Re: [ecco-support] Budgets in ECv4, release 3
>
> Thanks!  Have you done any budgets for the upper-ocean? For vertically
> integrated budgets the vertical convergences don't play a role.
> Martha
>
>
> On Thu, Nov 2, 2017 at 1:07 PM, Wang, Ou (329B) <Ou.Wang at jpl.nasa.gov>
> wrote:
>
>> Hi Martha,
>>
>> I closed the heat budget for the global ocean from top to bottom.
>>
>> Regards,
>> Ou
>>
>> From: <ecco-support-bounces at mit.edu> on behalf of Martha Buckley <
>> marthabuckley at gmail.com>
>> Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu>
>> Date: Thursday, November 2, 2017 at 10:04 AM
>> To: "ECCO support list, wider membership" <ecco-support at mit.edu>
>> Subject: Re: [ecco-support] Budgets in ECv4, release 3
>>
>> Hi Ou,
>> Thanks for the reply.  Can you tell me more about the type of budget that
>> you closed, e.g., the diagnostic (mass, heat, salt, etc) and the
>> layer/geographical area.  The reason that I am asking is that a budget over
>> a single grid cell may not need 64-bit precision, but when integrating over
>> depth, etc, the errors may accumulate.  I am currently looking at budgets
>> over the top 1000m for mass, heat, salt.
>>
>> A very long time ago, I did a budget calculation using MITgcm output that
>> did not close due to 32-bit output, and I changed to 64-bit output and it
>> closed (since then I have always used 64-bit output so I haven't verified
>> that this is necessary).
>>
>> thanks,
>> Martha
>>
>>
>>
>> On Thu, Nov 2, 2017 at 12:03 AM, Wang, Ou (329B) <Ou.Wang at jpl.nasa.gov>
>> wrote:
>>
>>> Hi Martha,
>>>
>>> I have closed the heat budget for the global ocean using the nctiles
>>> output available on ftp://ecco.jpl.nasa.gov/Version4/Release3/. The
>>> ratio of STD(tendency-convergences-forcing)/STD(tendency) is ~1e-7.
>>>
>>> Although the netCDF files are all in 64-bit precision, some of the
>>> original binary diagnostic outputs that were converted to the tiled netCDF
>>> files are in 32-bit precision. So apparently it is not necessary for the
>>> files to be in 64-bit precision to close budgets.
>>>
>>> Release 3 has geothermal flux. See Section 4.2.1 (page 10) of Chris
>>> Piecuch’s note
>>> <ftp://ecco.jpl.nasa.gov/Version4/Release3/doc/evaluating_budgets_in_eccov4r3.pdf> on
>>> budget calculation.
>>>
>>> Regards,
>>> Ou Wang
>>>
>>> From: <ecco-support-bounces at mit.edu> on behalf of Martha Buckley <
>>> marthabuckley at gmail.com>
>>> Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu>
>>> Date: Tuesday, October 31, 2017 at 7:35 AM
>>> To: "ECCO support list, wider membership" <ecco-support at mit.edu>
>>> Subject: [ecco-support] Budgets in ECv4, release 3
>>>
>>> Hi all,
>>> I am trying to close mass, heat, and salt budgets in ECCo v4 release 3.
>>> I closed the budgets to machine precision ((tendancy - ocean convergences -
>>> surfaceFluxes)/tendancy  ~ 1e-7)) for an older iteration.  However, I
>>> unable to close the budgets to machine precision for the files on the
>>> website for release3 (the budgets visually look fine though).
>>>
>>> I'm trying to figure out if I have a bug in my code or if something
>>> changed with the new output.  A few questions:
>>> (1) Are the files 64-bit precision, which is needed to close budgets?
>>> This seems to be the case since ncdump says the files are "double".
>>> (2) Did anything change between "r2/iter3" and release3 that might
>>> explain this?
>>> (3) Has anyone closed budgets for release3 using the nctiles output
>>> available on the ECCO website?
>>> thanks,
>>> Martha
>>>
>>>
>>>
>>>
>>> --
>>> Martha W. Buckley
>>> marthabuckley at gmail.com
>>> http://sites.google.com/site/marthabuckley/home
>>>
>>> _______________________________________________
>>> ecco-support mailing list
>>> ecco-support at mit.edu
>>> http://mailman.mit.edu/mailman/listinfo/ecco-support
>>>
>>>
>>
>>
>> --
>> Martha W. Buckley
>> marthabuckley at gmail.com
>> http://sites.google.com/site/marthabuckley/home
>>
>> _______________________________________________
>> ecco-support mailing list
>> ecco-support at mit.edu
>> http://mailman.mit.edu/mailman/listinfo/ecco-support
>>
>>
>
>
> --
> Martha W. Buckley
> marthabuckley at gmail.com
> http://sites.google.com/site/marthabuckley/home
>
> _______________________________________________
> ecco-support mailing list
> ecco-support at mit.edu
> http://mailman.mit.edu/mailman/listinfo/ecco-support
>
>

-- 
Martha W. Buckley
marthabuckley at gmail.com
http://sites.google.com/site/marthabuckley/home
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