[MITgcm-support] from C- to A-grid (particle tracking)

Andrea Cimatoribus andrea.cimatoribus at epfl.ch
Mon Mar 6 04:36:02 EST 2017


Dear all,
many shared some interest on lagrangian tools for MITgcm, so it's 
probably a good idea to share the repository where I am adapting 
tracmass to my MITgcm output:

https://github.com/sambarluc/tracmass

Tracmass nicely deals natively with C-grids, and only has some indexing 
differences with respect to MITgcm. For now I have a working example, 
but have done only a few tests and no documentation. Depending on how 
much time I will devote to this project, I may try to wrap things up in 
a nicer package in the future.

Thanks again to those who provided very valuable feedback.
Andrea


Andrea Cimatoribus
postdoctoral researcher
EPFL ENAC IIE ECOL
https://people.epfl.ch/andrea.cimatoribus

On 22/02/17 17:02, Andrea Cimatoribus wrote:
> Thanks for all the feedback, I have to study the material and may get
> back to (some of) you later.
> Cheers,
>
> Andrea Cimatoribus
> postdoctoral researcher
> EPFL ENAC IIE ECOL
> https://people.epfl.ch/andrea.cimatoribus
>
> On 22/02/17 15:34, Ryan Abernathey wrote:
>> Andrea,
>>
>> Moving from an A grid to a C grid does require interpolation. If you are
>> doing Lagrangian particles, the induced divergence might not be a
>> problem, since a slightly non-divergent velocity field won't cause any
>> serious problems. So a naive multilinear interpolation may be fine.
>>
>> If you need to advect tracers offline, you need a velocity field that is
>> exactly non divergent and satisfies the boundary condition at the side
>> walls. This can be obtained by decomposing the velocity into
>> streamfunction and velocity potential components, which requires solving
>> an elliptic Poisson PDE. The MITgcm can be hacked to solve this for you.
>>
>> We have done exactly what you describe in the following papers, where we
>> use AVISO geostrophic velocities (on an A-grid) to advect tracers and
>> particles within MITgcm.
>> http://doi.org/10.1002/jgrc.20066
>> http://doi.org/10.1175/JPO-D-13-0159.1
>> http://doi.org/10.1175/JPO-D-16-0215.1
>>
>> If you like, I can provide you more details.
>>
>> Cheers,
>> Ryan
>>
>>
>> On Wed, Feb 22, 2017 at 9:20 AM, Blundell J.R. <jeff at noc.soton.ac.uk
>> <mailto:jeff at noc.soton.ac.uk>> wrote:
>>
>>     Hi Andrea,
>>               This isn't a simple answer to your question, but you might
>>     like to have a look at ARIANE:
>>     http://stockage.univ-brest.fr/~grima/Ariane/
>>     <http://stockage.univ-brest.fr/~grima/Ariane/>
>>     (original webpage)
>>     which is heavily used here at NOC, Southampton. It has native support
>>     for some curvilinear C-grid models, such as OPA-NEMO and ROMS,
>>     though not (as far as I can see) MITgcm. Given that it has support
>> for
>>     several models, I would imagine that the logic of adding another
>> might
>>     not be too bad, perhaps easier that interpolating onto a regular
>> A-grid.
>>     We use v2.2.8_05 .
>>     See also
>>     http://salishsea-meopar-docs.readthedocs.org/en/latest/particles/
>>     <http://salishsea-meopar-docs.readthedocs.org/en/latest/particles/>
>>     which seems to have some of the most up-to-date documentation.
>>     I should explain that I build the software (that part works quite
>> well)
>>     for others to use; I'm not a user myself.
>>     http://earthscience.stackexchange.com/questions/761/what-are-some-
>>     options-for-online-and-offline-particle-tracking-in-ocean-models
>>     <http://earthscience.stackexchange.com/questions/761/what-are-some-
>>     options-for-online-and-offline-particle-tracking-in-ocean-models>
>>     seems to suggest that CMS can handle "various Arakawa-staggered
>> grids",
>>     as presumably it must if it handles HYCOM and ROMS output.
>>
>>                                 Jeff Blundell
>>
>> ======================================================================
>>     |              Research Fellow in Physical
>> Oceanography              |
>>     |                    e-mail:  jeff at noc.soton.ac.uk
>>     <mailto:jeff at noc.soton.ac.uk>                   |
>>     |   Jeff Blundell,  Room 256/09  |  OES Physical Oceanography
>> Group, |
>>     |    phone: +44 [0]23 8059 6201
>>     <tel:%2B44%20%5B0%5D23%208059%206201>  |  National Oceanography
>>     Centre,    |
>>     |     fax : +44 [0]23 8059 6204
>>     <tel:%2B44%20%5B0%5D23%208059%206204>  |  Southampton, European
>>     Way,       |
>>     |                                |  SOUTHAMPTON SO14 3ZH,
>> UK.        |
>>     |      WWW: http://www.southampton.ac.uk/oes/about/index.page
>>     <http://www.southampton.ac.uk/oes/about/index.page>?       |
>>
>> ======================================================================
>>
>>     ________________________________________
>>     From: Andrea Cimatoribus [andrea.cimatoribus at epfl.ch
>>     <mailto:andrea.cimatoribus at epfl.ch>]
>>     Sent: 22 February 2017 13:49
>>     To: mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>
>>     Subject: [MITgcm-support] from C- to A-grid (particle tracking)
>>
>>     Dear all,
>>     I am in the process of setting up some particle tracking experiments.
>>     After some research and some thinking about my needs, I am
>> inclined to
>>     use an offline tool rather than the MITgcm flt package, most
>> likely CMS
>>     (https://www.rsmas.miami.edu/users/cparis/oss.html
>>     <https://www.rsmas.miami.edu/users/cparis/oss.html>).
>>
>>     In order to use CMS, I need to interpolate the MITgcm results from my
>>     native curvilinear C-grid to the non curvilinear, non rotated A-grid
>>     which CMS requires. My questions then are:
>>     - is there a way to do this interpolation maintaining the flow (at
>> least
>>     approximately) non divergent? (with complex boundaries)
>>     - does anyone have any suggestion on working with MITgcm+CMS, or
>> more in
>>     general with MITgcm+particle tracking?
>>
>>     The alternative is to implement C-grids in CMS, which would be
>>     interesting but I'm not yet sure it's realistic.
>>
>>     Thanks, Andrea
>>
>>
>>     --
>>     Andrea Cimatoribus
>>     postdoctoral researcher
>>     EPFL ENAC IIE ECOL
>>     https://people.epfl.ch/andrea.cimatoribus
>>     <https://people.epfl.ch/andrea.cimatoribus>
>>
>>
>>
>>     PS: To answer the obvious question one may have: I think that the flt
>>     package is not the right tool for me, since I would like to have
>> several
>>     particles (>>1000), doing repeated experiments over the same
>> period of
>>     time, in a rather small domain. I think that an offline tool is in
>> this
>>     case not only much faster, but also much more flexible.
>>
>>     _______________________________________________
>>     MITgcm-support mailing list
>>     MITgcm-support at mitgcm.org <mailto:MITgcm-support at mitgcm.org>
>>     http://mitgcm.org/mailman/listinfo/mitgcm-support
>>     <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>>
>>     --
>>     This message has been scanned for viruses and
>>     dangerous content by MailScanner, and is
>>     believed to be clean.
>>
>>
>>     _______________________________________________
>>     MITgcm-support mailing list
>>     MITgcm-support at mitgcm.org <mailto:MITgcm-support at mitgcm.org>
>>     http://mitgcm.org/mailman/listinfo/mitgcm-support
>>     <http://mitgcm.org/mailman/listinfo/mitgcm-support>
>>
>>
>>
>>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support



More information about the MITgcm-support mailing list