[MITgcm-support] convertEmP2rUnit
Alistair Adcroft
adcroft at MIT.EDU
Mon Nov 17 08:40:38 EST 2003
Ah damn - I at least hoped Martin would be on my side ... Loks like J-M wins
this one.
A.
--
Dr Alistair Adcroft http://www.mit.edu/~adcroft
MIT Climate Modeling Initiative tel: (617) 253-5938
EAPS 54-1523, 77 Massachusetts Ave, Cambridge, MA, USA
-----Original Message-----
From: mitgcm-support-bounces at mitgcm.org
[mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Martin Losch
Sent: Monday, November 17, 2003 2:56 AM
To: MITgcm Support
Subject: Re: [MITgcm-support] convertEmP2rUnit
Jean-Michel, Alistair,
Steve Griffies suggested replacing rhoConstFresh by the actual insitu
fresh water density (which could be computed according to the used
EOS). Otherwise I don't have any new suggestions, so it's probably a
good idea to use Jean-Michel's new definition of convertEmP2rUnit. As
far as I remember we have thought about that last year, too, but
somehow dismissed it.
It would be interesting to see whether this improves the fit between
Boussinesq and non-Boussinesq model, but I don't dare to have a look (o:
Martin
On Friday, November 14, 2003, at 03:20 PM, Alistair Adcroft wrote:
> I think the next time I hear about horizVertRatio I'll scream; your
> point is well taken that a consistent conversion is necessary and some
> flexibility
> and intellegence on the models part is necessary. However,
> horizVertRatio is
> a historical left-over from the strictly p-coordiante days which I
> wanted to
> eliminate when I first implemented r-coordinates but some cry babies
> cried;
> it is currently a proxy for dr/dz and this is exactly the factor you
> are
> looking for when converting FW to r-dot. Yet another thing to flag for
> tidy
> up.
>
> A.
> --
> Dr Alistair Adcroft http://www.mit.edu/~adcroft
> MIT Climate Modeling Initiative tel: (617) 253-5938
> EAPS 54-1523, 77 Massachusetts Ave, Cambridge, MA, USA
>
> -----Original Message-----
> From: mitgcm-support-bounces at mitgcm.org
> [mailto:mitgcm-support-bounces at mitgcm.org] On Behalf Of Jean-Michel
> Campin
> Sent: Thursday, November 13, 2003 7:45 PM
> To: mlosch at awi-bremerhaven.de
> Cc: mitgcm-support at mitgcm.org
> Subject: [MITgcm-support] convertEmP2rUnit
>
>
> Hi Martin,
>
> I think that convertEmP2rUnit should be:
> convertEmP2rUnit = rhoConstFresh*recip_rhoConst*horiVertRatio
> and not:
> =1. [if ocean-Z]
> =rhoConstFresh*Gravity [if ocean-P]
> as it is now.
>
> The result is the same for ocean-P since
> horiVertRatio=rhoConst*Gravity in this case (and horiVertRatio=1 in
> ocean-Z).
>
> My point is:
> if we think that a different rhoConst for Fresh water
> is needed in the ocean-P, then it seems logical to have the same
> ability in ocean-Z.
>
> The reason why I ask this is that I started to use rhoConstFresh for
> the density of the fresh water with sea-ice component and with
> atmospheric model, and cannot reach a perfect conservation unless I
> set rhoConstFresh=rhoConst, simply because presently
> convertEmP2rUnit=1. whatever rhoConstFresh/rhoConst is.
>
> What do you think ?
>
> Jean-Michel
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> MITgcm-support at mitgcm.org
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>
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