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Hi Igor,</div>
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<br>
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it is perfectly possible to compute a reference state to compute available potential energy despite the nonlinear equation of state, as explained in the following paper (Saenz et al. 2015, JPO) </div>
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<br>
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<a href="https://doi.org/10.1175/JPO-D-14-0105.1" id="LPlnk124238">https://doi.org/10.1175/JPO-D-14-0105.1</a><br>
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<br>
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Now, it is also possible to show that the 'true' available potential energy can be usefully approximately by taking the horizontally-averaged density field as an approximation to the true reference state as explained in Tailleux (JFM, 2013).</div>
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<br>
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<a href="https://doi.org/10.1017/jfm.2013.509" id="LPlnk779257">https://doi.org/10.1017/jfm.2013.509</a><br>
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<br>
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Computing a good approximation of available potential energy for the ocean is much easier than most people imagine. The idea that it is (nearly) impossible to compute a meaningful APE budget for the ocean has been greatly exaggerated. </div>
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<br>
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Good luck,</div>
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Remi.</div>
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<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> MITgcm-support <mitgcm-support-bounces@mitgcm.org> on behalf of mitgcm-support-request@mitgcm.org <mitgcm-support-request@mitgcm.org><br>
<b>Sent:</b> 12 June 2020 17:00<br>
<b>To:</b> mitgcm-support@mitgcm.org <mitgcm-support@mitgcm.org><br>
<b>Subject:</b> MITgcm-support Digest, Vol 204, Issue 5</font>
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Today's Topics:<br>
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1. Potential energy in MITgcm (Shevchenko, Igor)<br>
2. Re: Potential energy in MITgcm (Martin Losch)<br>
3. Re: Potential energy in MITgcm (Shevchenko, Igor)<br>
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Message: 1<br>
Date: Fri, 12 Jun 2020 09:23:02 +0000<br>
From: "Shevchenko, Igor" <i.shevchenko@imperial.ac.uk><br>
To: mitgcm-support <mitgcm-support@mitgcm.org><br>
Subject: [MITgcm-support] Potential energy in MITgcm<br>
Message-ID:<br>
<DB7PR06MB440935B3EC2B8F8766DEB425AA810@DB7PR06MB4409.eurprd06.prod.outlook.com><br>
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Dear MITgcm users,<br>
<br>
Is there a chance to diagnose potential energy in MITgcm?<br>
<br>
Best regards,<br>
Igor<br>
<br>
------------------------------<br>
<br>
Message: 2<br>
Date: Fri, 12 Jun 2020 11:30:59 +0200<br>
From: Martin Losch <Martin.Losch@awi.de><br>
To: MITgcm Support <mitgcm-support@mitgcm.org><br>
Subject: Re: [MITgcm-support] Potential energy in MITgcm<br>
Message-ID: <E76E9133-E9AE-4566-AE4F-37A5EDBD5D4E@awi.de><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Hi Igor,<br>
<br>
rhethorical question: what is potential energy in a GCM?<br>
<br>
This is a bit complicated. You could just intergrate density vertically (and density or density anomaly can be saved via the diagnostics pkg), but you really only want to have available potential density, for which you need a reference state that is difficult
(impossible?) to define for general case. So it?s always set-up specific.<br>
<br>
Details of the actual computation also depend on details of your configuration (free surface linear/non-linear/r-star, etc.)<br>
<br>
M.<br>
<br>
> On 12. Jun 2020, at 11:23, Shevchenko, Igor <i.shevchenko@imperial.ac.uk> wrote:<br>
> <br>
> Dear MITgcm users,<br>
> <br>
> Is there a chance to diagnose potential energy in MITgcm?<br>
> <br>
> Best regards,<br>
> Igor<br>
> _______________________________________________<br>
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> MITgcm-support@mitgcm.org<br>
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------------------------------<br>
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Message: 3<br>
Date: Fri, 12 Jun 2020 09:55:55 +0000<br>
From: "Shevchenko, Igor" <i.shevchenko@imperial.ac.uk><br>
To: "mitgcm-support@mitgcm.org" <mitgcm-support@mitgcm.org><br>
Subject: Re: [MITgcm-support] Potential energy in MITgcm<br>
Message-ID:<br>
<DB7PR06MB4409386F14FFAE2FCA822660AA810@DB7PR06MB4409.eurprd06.prod.outlook.com><br>
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Content-Type: text/plain; charset="Windows-1252"<br>
<br>
Hi Martin,<br>
<br>
Thank you for the answer.<br>
I just thought there might be something about it in MITgcm I missed.<br>
<br>
Best regards,<br>
Igor<br>
<br>
________________________________________<br>
From: MITgcm-support <mitgcm-support-bounces@mitgcm.org> on behalf of Martin Losch <Martin.Losch@awi.de><br>
Sent: 12 June 2020 10:30<br>
To: MITgcm Support<br>
Subject: Re: [MITgcm-support] Potential energy in MITgcm<br>
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Hi Igor,<br>
<br>
rhethorical question: what is potential energy in a GCM?<br>
<br>
This is a bit complicated. You could just intergrate density vertically (and density or density anomaly can be saved via the diagnostics pkg), but you really only want to have available potential density, for which you need a reference state that is difficult
(impossible?) to define for general case. So it?s always set-up specific.<br>
<br>
Details of the actual computation also depend on details of your configuration (free surface linear/non-linear/r-star, etc.)<br>
<br>
M.<br>
<br>
> On 12. Jun 2020, at 11:23, Shevchenko, Igor <i.shevchenko@imperial.ac.uk> wrote:<br>
><br>
> Dear MITgcm users,<br>
><br>
> Is there a chance to diagnose potential energy in MITgcm?<br>
><br>
> Best regards,<br>
> Igor<br>
> _______________________________________________<br>
> MITgcm-support mailing list<br>
> MITgcm-support@mitgcm.org<br>
> <a href="http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support">http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support</a><br>
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