[MITgcm-support] 回复： 回复： barotropic nondivergent run

[钱钰坤]

Hi Ryan,


Thanks very much for your reply and sharing your python QG model.  Non-divergent is essential to me, not QG.


I'll try some simulations with and without rigid lid option and then see the differences.


------------------
 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      


 
 
 
------------------ 原始邮件 ------------------
发件de人: "Ryan Abernathey"<ryan.abernathey at gmail.com>;
发送时间: 2015年7月20日(星期一) 中午11:00
收件人: "mitgcm-support at mitgcm.org"<mitgcm-support at mitgcm.org>; 

主题: Re: [MITgcm-support]回复： barotropic nondivergent run

 
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      


 
 
 
------------------ 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      


 

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