[ecco-support] ecco-support Digest, Vol 99, Issue 16

[Xinfeng Liang]

Hong, Ou,

Thank you for the explanation. I understand it now.

Best,
Xinfeng


On Sat, Jun 29, 2024 at 7:33 PM <ecco-support-request at mit.edu> wrote:

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>    1. Re: [EXTERNAL] Re:  ecco-support Digest, Vol 99, Issue 13
>       (Zhang, Hong (US 398K))
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> Date: Sat, 29 Jun 2024 23:33:17 +0000
> From: "Zhang, Hong (US 398K)" <hong.zhang at jpl.nasa.gov>
> To: "ECCO support list, wider membership" <ecco-support at mit.edu>
> Subject: Re: [ecco-support] [EXTERNAL] Re:  ecco-support Digest, Vol
>         99, Issue 13
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> On Jun 29, 2024, at 4:13?PM, Wang, Ou (US 329B) <ou.wang at jpl.nasa.gov>
> wrote:
>
> Hi Xinfeng,
>
> In terms of z* and the real freshwater flux boundary condition, there is
> no change between v4r1 and v4r4. The smaller horizontal integral of the
> Eulerian vertical velocity We (i.e. WVELMASS) in Figure 6 of your paper is
> probably because you were looking at the time-mean value. I did a quick
> calculation of the horizontal integrals of WVELMASS for v4r1. The time-mean
> value is only a few percent of Sv's, one to two orders of magnitude smaller
> than that for a particular month.
> Here is an earlier discussion of WVEL with Carl.
> Hope it helps for this theme of discussion.
>
> An interesting question, but your result and description is exactly what
> one would expect if I've
> understood you.
>
> Even the twenty year average wvel is noisy (see the Liang etal attachment)
> particularly at
> depth. One slightly troubling numerical problem is that w is computed (as
> I understand it)
> as the residual divergence of the horizontal velocity at any given
> time---and that's an intrinsically
> noisy method.
>
> Furthermore, in theory at hourly time steps, the internal wave field is in
> principle present (the
> spatial resolution of 1 degree means that it wouldn't be realistic, but
> the physics should apply). That
> field, and see some of the ECCO high resolution results in the other
> attachment) is known to be almost fully stochastic (tides
> aside) and is described by a frequency/wavenumber spectrum (Garrett-Munk).
> An then at low latitudes,
> the 1 degree resolution is probably sufficient to produce an eddy-like
> field, which is also stochastic.
> An interesting question would be what would w look like if you could
> average for 50 or 500 years?
>
>
> Carl
>
>
>
> Hi Carl,
> A quick question about Eulerian vertical velocity.
> Normally we look at monthly/yearly/decadal mean WVEL
> (like fig 18 in your BAMS paper for 20-yr mean WVEL).
> But when we look at the hourly or daily mean,
> it's surprised that WVEL field looks "messy" (or "grid noisy")
> and larger by order of magnitude,
> So WVEL must vary rapidly with time and place
> and only after much cancellation does it look "normal" (as classical
> gyre and upwelling).
> Have you touched upon this phenomenon in your papers?
> Or are you aware where it is discussed in the literature?
>
> cheers
> Hong
>
>
>
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