[ecco-support] Budgets in ECv4, release 3

[Wang, Ou (329B)]

Hi Martha,

I closed the heat budget for the global ocean from top to bottom.

Regards,
Ou

From: <ecco-support-bounces at mit.edu<mailto:ecco-support-bounces at mit.edu>> on behalf of Martha Buckley <marthabuckley at gmail.com<mailto:marthabuckley at gmail.com>>
Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu<mailto: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<mailto: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<mailto: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<mailto:ecco-support-bounces at mit.edu>> on behalf of Martha Buckley <marthabuckley at gmail.com<mailto:marthabuckley at gmail.com>>
Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu<mailto: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<mailto: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<mailto:marthabuckley at gmail.com>
http://sites.google.com/site/marthabuckley/home

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