[ecco-support] ecco-support Digest, Vol 99, Issue 13

Sat Jun 29 14:48:47 EDT 2024

Hi All,

Is it possible that this issue depends on the version of ECCO? I did a
similar calculation a long time ago with ECCO v4r1, and the horizontal
integrals of We and Wb were both zero (almost). Check out Figure 6 of this
paper https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JC012985.
Has anything changed since then that could affect this?

Best,
Xinfeng
---------------------------
Xinfeng Liang
Associate Professor
School of Marine Science and Policy
University of Delaware

700 Pilottown Road
Lewes, DE 19958
302-645-4036
xfliang at udel.edu
https://sites.udel.edu/xfliang/

On Fri, Jun 28, 2024 at 12:00 PM <ecco-support-request at mit.edu> wrote:

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> Today's Topics:
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>    1. Re: Global integral of vertical momentum flux not zero?
>       (Jean-Michel Campin)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 28 Jun 2024 11:44:40 -0400
> From: Jean-Michel Campin <jmc at mit.edu>
> To: "ECCO support list, wider membership" <ecco-support at mit.edu>
> Subject: Re: [ecco-support] Global integral of vertical momentum flux
>         not zero?
> Message-ID: <20240628154440.GA20988 at ocean.mit.edu>
> Content-Type: text/plain; charset=us-ascii
>
> Hi Paola and Fabien,
>
> Ou is right, the horizontal integral of wVel is not zero because of z*.
> With z*, wVel(k) (which corresponf to (H+Eta)/H*w* in the 2004 paper eq
> 11) is computed
> by integrating eq.11 from bottom to level k,
> but because the depth H is not uniform everywhere (not a flat bottom)
> this second contribution is not zero when integrated vertically to
> interface k, and this
> is the case even if the global integral of d.Eta/dt was zero (which I am
> not sure it is,
> with frrsh water input and seaice, but it's an other story).
>
> Cheers,
> Jean-Michel
>
> On Fri, Jun 28, 2024 at 03:07:53PM +0000, Menemenlis, Dimitris (US 329B)
> wrote:
> > Paola, Ou, and Fabien, I wonder if non-zero Evaporation minus
> Precipitation minus Runoff (EmPmR), including freshwater exchange with sea
> ice, could be the cause of non-zero WVELMASS in a ???realfreshwaterflux???
> MITgcm configuration?
> >
> > But these realfreshwaterflux volume fluxes could probably not explain
> ???order several Sv??? of horizontal integral of w.  Back of the envelope,
> a 2-cm sea level seasonal cycle of land-to-ocean mass transfer is a ~0.2 Sv
> vertical velocity at surface.  The Greenland and Antarctic mass loss is of
> order ~0.01 Sv at the surface.  The seasonal cycle of freshwater exchange
> with sea ice is ~1 Sv around Antarctica and 0.5 Sv in Arctic.  Subsurface
> WVELMASS would be proportionately smaller in z* coordinates.
> >
> > Dimitris
> >
> >
> > On Jun 28, 2024, at 1:51???AM, Paola Cessi <pcessi at ucsd.edu> wrote:
> >
> > Hi Ou,
> >
> > could you please elaborate of why this is the case? When I look at
> Adcroft & Campin 2004 (A&C04), even in z* coordinates WVELMASS should have
> zero horizontal integral. If you look at eq 11 of A&C04, the continuity eqn
> has an extra term (independent of z) given by \eta_t, but I believe it also
> has zero area average, when you compare it to (12) in A&C04, because the
> area integral of E-P is also made to be zero in ECCO. Unless there is
> something to do with the ice, which is not covered in A&C04, I don???t see
> why <w> is not zero.
> >
> > Can you please enlighten us?
> >
> > Many thanks,
> > Paola
> >
> > On Jun 27, 2024, at 2:17???AM, Wang, Ou (US 329B) <ou.wang at jpl.nasa.gov>
> wrote:
> >
> > Hello Fabien,
> >
> > You haven???t missed anything in your calculation. The horizontal
> integral of area-weighted vertical velocity (WVELMASS) across a particular
> vertical level does not necessarily equal zero.
> >
> > Best regards,
> > Ou Wang
> >
> > From: ecco-support <ecco-support-bounces at mit.edu<mailto:
> ecco-support-bounces at mit.edu>> on behalf of Fabien Roquet <
> fabien.roquet at gu.se<mailto:fabien.roquet at gu.se>>
> > Date: Monday, June 24, 2024 at 1:15???PM
> > To: ecco-support at mit.edu<mailto:ecco-support at mit.edu> <
> ecco-support at mit.edu<mailto:ecco-support at mit.edu>>
> > Subject: [EXTERNAL] [ecco-support] Global integral of vertical momentum
> flux not zero?
> > Hello ECCO team,
> > I have downloaded ECCO from PO.DAAC.
> > Using WVELMASS from ECCO_L4_OCEAN_3D_VOLUME_FLUX_LLC0090GRID_DAILY_V4R4,
> multiplying with rA and summing along i, j, and tiles, I find the
> horizontal integral of w is not zero. Am I missing something?
> > See picture for the vertical profile of w, which is of order several Sv.
> > Thanks for your help,
> > Fabien
> >
> >
>
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> > ecco-support at mit.edu
> > https://mailman.mit.edu/mailman/listinfo/ecco-support
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>
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> End of ecco-support Digest, Vol 99, Issue 13
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