[ecco-support] ecco-support Digest, Vol 78, Issue 3

[aviv solodoch]

Dear Ou
Thanks for your reply! Just one clarification question please regarding
"H(t) is model depth at time t". I'm assuming that the depth relates to the
same model vertical column as the OBP cell. Why should the depth depend on
time? Does it include sea surface height?
Thanks,
Aviv Solodoch,
Postdoctoral researcher,
UCLA,
Department of Atmospheric and Oceanic Sciences


On Mon, Aug 22, 2022 at 1:15 PM <ecco-support-request at mit.edu> wrote:

> Send ecco-support mailing list submissions to
>         ecco-support at mit.edu
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         https://mailman.mit.edu/mailman/listinfo/ecco-support
> or, via email, send a message with subject or body 'help' to
>         ecco-support-request at mit.edu
>
> You can reach the person managing the list at
>         ecco-support-owner at mit.edu
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of ecco-support digest..."
>
>
> Today's Topics:
>
>    1. ECCOv4r3 OBP units (aviv solodoch)
>    2. Re: [EXTERNAL]  ECCOv4r3 OBP units (Wang, Ou (US 329B))
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 22 Aug 2022 22:13:30 +0300
> From: aviv solodoch <avivsolo at gmail.com>
> To: ecco-support at mit.edu
> Subject: [ecco-support] ECCOv4r3 OBP units
> Message-ID:
>         <CAPu===NLCuZN3=QYBeB77jCgGkxEjU_U9N+VYf9e=
> 9AESZxmKw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hello
> Can you please let me know what are the ECCOv4r3 units for the OBP
> variable? The ECCO output fields document says it is given in meters, but
> the actual values at depths of several kms are of order 10s (of meters I
> guess) rather than similar in value to the depths. Can you please explain
> what kind of conversion was made here?
> Regards,
> Aviv Solodoch,
> Postdoctoral researcher,
> UCLA,
> Department of Atmospheric and Oceanic Sciences
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://mailman.mit.edu/pipermail/ecco-support/attachments/20220822/edc0b094/attachment-0001.htm
> >
>
> ------------------------------
>
> Message: 2
> Date: Mon, 22 Aug 2022 20:15:24 +0000
> From: "Wang, Ou (US 329B)" <ou.wang at jpl.nasa.gov>
> To: "ECCO support list, wider membership" <ecco-support at mit.edu>
> Subject: Re: [ecco-support] [EXTERNAL]  ECCOv4r3 OBP units
> Message-ID: <409DC881-01EB-41EC-BBB9-C1FF3A9656B7 at jpl.nasa.gov>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Aviv,
>
> ECCO V4r3 OBP files in
> https://ecco.jpl.nasa.gov/drive/files/Version4/Release3/nctiles_monthly/OBP
> are in meters. To compare with GRACE data, one would need to remove its
> area-weighted global ocean mean and also a temporal mean (ideally over the
> same averaging period GRACE data use to remove its temporal mean). The meta
> data has since bee improved in ECCO V4r4. Attached below is the updated
> meta data for the ECCO V4r4 monthly-mean OBP fields (
> https://podaac.jpl.nasa.gov/dataset/ECCO_L4_OBP_LLC0090GRID_MONTHLY_V4R4)
> that has detailed description about what exactly the OBP fields are.
>
> "OBP excludes the contribution from global mean atmospheric pressure and
> is therefore suitable for comparisons with GRACE data products. OBP is
> calculated as follows. First, we calculate ocean hydrostatic bottom
> pressure anomaly, PH
> IBOT, with PHIBOT = p_b/rhoConst - gH(t), where p_b = model ocean
> hydrostatic bottom pressure, rhoConst = reference density (1029 kg m-3), g
> is acceleration due to gravity (9.81 m s-2), and H(t) is model depth at
> time t. Then, OBP = PHIBOT/g + corrections for i) global mean steric sea
> level changes related to density changes in the Boussinesq
> volume-conserving model (Greatbatch correction, see sterGloH) and ii)
> global mean atmospheric pressure variations. Use OBP for comparisons with
> ocean bottom pressure data products that have been corrected for global
> mean atmospheric pressure variations. GRACE data typically ARE corrected
> for global mean atmospheric pressure variations. In contrast, ocean bottom
> pressure gauge data typically ARE NOT corrected for global mean atmospheric
> pressure variations." ;
>
> Best,
> Ou Wang
>
>
> From: ecco-support <ecco-support-bounces at mit.edu> on behalf of aviv
> solodoch <avivsolo at gmail.com>
> Reply-To: "ECCO support list, wider membership" <ecco-support at mit.edu>
> Date: Monday, August 22, 2022 at 12:35 PM
> To: "ecco-support at mit.edu" <ecco-support at mit.edu>
> Subject: [EXTERNAL] [ecco-support] ECCOv4r3 OBP units
>
> Hello
> Can you please let me know what are the ECCOv4r3 units for the OBP
> variable? The ECCO output fields document says it is given in meters, but
> the actual values at depths of several kms are of order 10s (of meters I
> guess) rather than similar in value to the depths. Can you please explain
> what kind of conversion was made here?
> Regards,
> Aviv Solodoch,
> Postdoctoral researcher,
> UCLA,
> Department of Atmospheric and Oceanic Sciences
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://mailman.mit.edu/pipermail/ecco-support/attachments/20220822/a6276317/attachment.htm
> >
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> ecco-support mailing list
> ecco-support at mit.edu
> https://mailman.mit.edu/mailman/listinfo/ecco-support
>
>
> ------------------------------
>
> End of ecco-support Digest, Vol 78, Issue 3
> *******************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mit.edu/pipermail/ecco-support/attachments/20220822/0f28452a/attachment-0001.htm>