[MITgcm-support] vertical momentum tendency

[Martin Losch]

I am not sure, if this is a useful comment, but even in a non-hydrostatic simulation, the flow field is non-divergent and you coiuld diagnose wVel from the vertical integral of the horizontal divergence (in fact, the model does this in a non-hydrostatic simulation, too). In the same way, and since the operations are linear you coud diagnose dw/t from - \nabla_h du/dt, couldn’t you?

Martin

> On 23. May 2022, at 15:36, 钱钰坤 <qianyk at mail3.sysu.edu.cn> wrote:
> 
> Hi,
> 
> I might find a workaround to get instantaneous TOTWTEND (not time-mean one)
> by adding the following lines:
>   CALL DIAGNOSTICS_SCALE_FILL( wVel, tmpFac, 1, 'TOTWTEND',0,Nr,0,1,1,myThid )
> to diagnostics_fill_state.F file, following TOTUTEND and TOTVTEND  (see here <https://github.com/MITgcm/MITgcm/blob/20a156cdcefcb000006123cf7ddac8fc997cb603/pkg/diagnostics/diagnostics_fill_state.F#L356>).  And
> also add a call to 
>   CALL DIAGNOSTICS_ADDTOLIST()
> at diagnostics_main_init.F (see here <https://github.com/MITgcm/MITgcm/blob/20a156cdcefcb000006123cf7ddac8fc997cb603/pkg/diagnostics/diagnostics_main_init.F#L781>).
> 
> Then I re-compile the model and run it well.  However, the tendency of w TOTWTEND
> seems to be much larger than expected in my case:
> <7239677D at 602E0261.C58D8B62.png>
> 
> I am not sure DIAGNOSTICS_SCALE_FILL really do the time-differencing.  Is this
> the right way to get TOTWTEND?  Why it looks so large in magnitude?
> 
> Best regards 
> 
> -----------------------------------------
> Yu-Kun Qian (钱钰坤)
> South China Sea Institute of Oceanology
> Sun Yat-sen University
> Xingang West Road, Haizhu District
> Guangzhou, P.R. China
> Email: qianyukun at scsio.ac.cn, qianyk at mail3.sysu.edu.cn <mailto:qianyk at mail2.sysu.edu.cn>
>  
>  
> ------------------ 原始邮件 ------------------
> 发件人: "Matthew Mazloff"<mmazloff at ucsd.edu>;
> 发送时间: 2022年5月18日(星期三) 上午9:47
> 收件人: "MITgcm-support"<mitgcm-support at mitgcm.org>;
> 主题: Re: [MITgcm-support] vertical momentum tendency
>  
> Hi Haoron
> 
> Dump snapshots at the interval you need to get dW/dt.
> 
> For example daily tendency would be derived from
>    frequency(1) = -86400.0,
>    timePhase(1) = 0.0,
>    fields(1,1) = 'WVEL    ',
>    filename(1) = ‘WvelSnap’,
> 
> 
> Matt
> 
> 
>> On May 17, 2022, at 5:47 PM, 钱钰坤 <qianyk at mail3.sysu.edu.cn <mailto:qianyk at mail3.sysu.edu.cn>> wrote:
>> 
>> Hi Haoran,
>> 
>> Thank you for your help.  But I don't really know how these two diagnostics
>> could help in deriving the tendency of w (unit of acceleration).
>> 
>> My understanding is that these two diagnostics are useful in calculating the
>> eddy momentum flux when the output is time-average <> one.  For example,
>> <w'u'> = <wu> - <w><u>
>> If we output monthly mean wu, w, and u, we can get eddy flux <w'u'> for this
>> month.
>> 
>> Best regards 
>> 
>> -----------------------------------------
>> Yu-Kun Qian (钱钰坤)
>> South China Sea Institute of Oceanology
>> Sun Yat-sen University
>> Xingang West Road, Haizhu District
>> Guangzhou, P.R. China
>> Email: qianyukun at scsio.ac.cn <mailto:qianyukun at scsio.ac.cn>, qianyk at mail3.sysu.edu.cn <mailto:qianyk at mail2.sysu.edu.cn>
>>  
>>  
>>  
>>  
>> ------------------ 原始邮件 ------------------
>> 发件人: "Haoran Xu"<xu1jian2wei3 at 163.com <mailto:xu1jian2wei3 at 163.com>>;
>> 发送时间: 2022年5月17日(星期二) 晚上7:40
>> 收件人: "MITgcm-support"<mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>>;
>> 主题: Re: [MITgcm-support] vertical momentum tendency
>>  
>> Hi，
>>  If I understand correctly,these two diagnostics could help.
>> 
>> 
>> WU_VEL  |WU      LR|m.m/s^2         |Vertical Transport of Zonal Momentum
>> WV_VEL  |WV      LR|m.m/s^2         |Vertical Transport of Meridional Momentum
>> 
>>  Haoran Xu.
>> 
>> At 2022-05-17 18:30:48, "钱钰坤" <qianyk at mail3.sysu.edu.cn <mailto:qianyk at mail3.sysu.edu.cn>> wrote:
>> 
>> Hi all,
>> 
>> Just a quick question.  Why there is no tendency of vertical momentum,
>> like TOTWTEND, in the diagnostics even the non-hydrostatic option is
>> turned on?
>> 
>> To close the energy budget, I guess we need this diagnostic.  Is there any
>> workaround to obtain it if there is no TOTWTEND?
>> 
>> Best regards.
>> 
>> ---------------------------
>> Yu-Kun Qian (钱钰坤)
>> South China Sea Institute of Oceanology
>> Sun Yat-sen University 
>> Xingang West Road, Haizhu District 
>> Guangzhou, P.R. China
>> Email: qianyk at mail3.sysu.edu.cn <mailto:qianyk at mail2.sysu.edu.cn>
>>  
>>  
>> 
>> 
>>  
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