[MITgcm-support] Open boundary conditions using ECCO data

Thu Apr 27 20:44:50 EDT 2017

Hi Longjiang,

Thanks for your answer. I guess my question is not very clear. Actually there are two kinds of data for ECCO v4: one is original grid data (LLC90), one is interpolated grid data (1/2 degree). hFacS and hFacW are available for the former grid (generated during model initialization as you said) but not for the later one. My question would be that how can I obtain UVEL or VVEL from UVELMASS or VVELMASS when hFacS and hFacW are not given for the interpolated grid. The transfering of UVEL and VVEL to my model grid has not been considered here.

Thanks for further comments.

Delei

________________________________
From: Longjiang Mu <mulongjiang at qq.com>
Sent: 27 April 2017 15:30:22
To: mitgcm-support at mitgcm.org
Subject: Re: [MITgcm-support] Open boundary conditions using ECCO data

Hi Delei,

hFacS or hFacW ... are generated during model initialization.
I think for new grids maybe you'll need UVEL or VVEL, then you can try
to fill the grids where hFacW/hFacS < 1.0 with UVEL or VVEL.
If you just have UVELMASS or VVELMASS, maybe UVEL can be got by
UVEL=UVELMASS/hFacW.
And don't forget to balance the boundary flux after that.

Longjiang
在 2017年04月27日 00:00, mitgcm-support-request at mitgcm.org 写道:
> Hi Martin,
>
>
> Thanks for your kind answer, which is the first reply I received :)
>
> Here is another question about how to get hFacW and hFacS. I am using the ECCO-v4 1/2 degree interpolted fields (ftp://mit.ecco-group.org/ecco_for_las/version_4/release2/interp_monthly/). So should I calculate hFacW and hFacS by myself  based on the interpolated grid faces rather than use them directly under ftp://mit.ecco-group.org/ecco_for_las/version_4/grids/grids_output/ECCOv4/ ? (which I guess for the original ECCO grid not interpolated grid)
>
>
> All the best,
>
> Delei
>
> ________________________________
> From: Martin Losch <Martin.Losch at awi.de>
> Sent: 24 April 2017 15:53:39
> To: MITgcm Support
> Subject: Re: [MITgcm-support] Open boundary conditions using ECCO data
>
> Hi Delei Li,
>
> did you get an answer?
>
> I think you can ignore the bolus velocities. They are computed from the Gent-McWilliams Eddy parameterisation and represent the eddy flux of a tracer.
>
> The mass weighted velocities are hFacW*UVEL and hFacS*VVEL. You should probably back out UVEL and VVEL and use them to drive you model.
>
> Martin
>> On 14 Apr 2017, at 08:05, ?? ? <Deleili at hotmail.com> wrote:
>>
>> Hi all,
>>
>> I am running a regional version of MITgcm with exf and obcs packages turned on. I would like to use global ECCO u/v/t/s data (ftp://mit.ecco-group.org/ecco_for_las/version_4/release2/interp_monthly/) as the boundary forcings of my regional model.
>> However, I have some problems with the forcing data preparation.
>>
>> (1) There are two kinds of velocity in ECCO v4r2 dataset: Mass-Weighted Comp of Velocity and Bolus Velocity, which one should I use as the velocity boundary forcings?  I prefer the former one, but not very sure about it.
>> (2) As the velocity is available in form of mass-weighted, should I make some conversion on it and then interpolate to target  grids?  Or directly interpolate mass-weighted velocity to target grids at vertical levels of each boundary?
>>
>> Does anyone have any suggestion on the questions? Your help would be much appreciated.
>>
>> Best regards,
>> Delei Li
>> ----------------------------------------------------------------
>> Key Laboratory of Ocean Circulation and Waves,
>> Institute of Oceanology, Chinese Academy of Sciences,
>> Nanhai Street No. 7, 266071, Qingdao, P.R. China
>> Telephone: 0532-82898839
>>
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