[MITgcm-support] 回复： barotropic nondivergent run

[Ryan Abernathey]

Yu-Kun,

You are correct--you can make the MITgcm into a 2D, non-divergent
barotropic model by using only one vertical level and a rigid lid. You can
also use a cartesian geometry. However, you can't make it formally
"quasigeostrophic" because it is at its core a primitive equation model. In
practice you might find a configuration that obeys QG dynamics to a good
approximation, but it will not be exact.

If you really want to to QG simulations, you should probably use a
different model. If you can live with doubly-periodic boundary conditions,
I will humbly suggest the python-based QG model I have been developing
along with a few other people, pyqg:
https://github.com/rabernat/pyqg

If you want sidewalls or bottom bathymetry, you will need something else
for now.

Best,
Ryan


On Sun, Jul 19, 2015 at 10:27 PM, 钱钰坤 <qianyk at mail3.sysu.edu.cn> wrote:

> Hi Matt,
>
> Thanks for your reply but it seems a little odd to me that the model is
> always non-divergent, at least for horizontal non-divergent (not 3D
> non-divergent).
>
> For atmosphere simulation, horizontal non-divergent model may limit the
> evolution of synoptic systems.  For non-hydrostatic simulation in the
> ocean, non-divergent dynamics is also improper.
>
> I can find a pre-defined momentum diagnostic monHDIV representing the
> horizontal divergence.
>
> As I see, in a barotropic model described by three variables (u, v, h),
> free surface (h) variations are caused by mass convergence/divergence.
> When the non-divergence constrain is put, the model can be reduced to only
> a single variable streamfunction.  Then how can I used MITgcm to mimic such
> dynamics?
>
>
> ------------------
> Best regards
>
> Yu-Kun Qian (钱钰坤)
> Center for Monsoon and Environment Research
> Department of Atmospheric Sciences
> School of Environmental Science and Engineering
> Sun Yat-sen University
> No. 135 Xingang West Road, Haizhu District
> Guangzhou, 510275, P.R. China
> Tel; 020-84115227
> Email: qianyk at mail3.sysu.edu.cn <qianyk at mail2.sysu.edu.cn>
>
>
>
>
> ------------------ 原始邮件 ------------------
> *发件de人:* "Matthew Mazloff"<mmazloff at ucsd.edu>;
> *发送时间:* 2015年7月18日(星期六) 凌晨3:42
> *收件人:* "mitgcm-support"<mitgcm-support at mitgcm.org>;
> *主题:* Re: [MITgcm-support] barotropic nondivergent run
>
> Hi Yu-Kun
>
> The MITgcm is always non-divergent
>
> Matt
>
>
> On Jul 17, 2015, at 1:28 AM, 钱钰坤 <qianyk at mail3.sysu.edu.cn> wrote:
>
> Hi all,
>
> I want to investigate the wind-driven ocean dynamics using QG barotropic
> nondivergent setup of MITgcm.  So far as I know, QG (quasi-geostrophic)
> means using Cartesian coordinates with f0 and sbeta set in parameter file
> 'data' to mimic beta-plane approximation.  Barotropics means that only one
> single layer is used in the model.  I've no idea how to constrain the model
> to produce nondivergent flow.
>
> I guess using the rigid lid option to force the flow nondivergent but I'm
> not sure.  Can anyone give some suggestions?  Many thanks in advance.
>
>
> ------------------
> Best regards
>
> Yu-Kun Qian (钱钰坤)
> Center for Monsoon and Environment Research
> Department of Atmospheric Sciences
> School of Environmental Science and Engineering
> Sun Yat-sen University
> No. 135 Xingang West Road, Haizhu District
> Guangzhou, 510275, P.R. China
> Tel; 020-84115227
> Email: qianyk at mail3.sysu.edu.cn <qianyk at mail2.sysu.edu.cn>
>
>
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>
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