Is there any tools to output the "dia" at the time of "his"

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LiuZHQ
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Is there any tools to output the "dia" at the time of "his"

#1 Post by LiuZHQ » Mon Sep 05, 2011 10:17 am

Dear All,
I noticed that the standard momentum terms output file or the "dia" file is following the type of "avg", which is averaged during the time we defined.
My question is, can we also obtain the terms at a specific time, say the time of "his" for example?
Or is there any toolbox which can calculate the terms according to the standard "his" output?
any idea will be appreciated.

ZQ

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arango
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Re: Is there any tools to output the "dia" at the time of "h

#2 Post by arango » Tue Sep 06, 2011 8:27 pm

Well, the diagnostic terms involve a time-integral like the averages files. I usually recommend to have NAVG=NDIA to facilitate computing budgets and fluxes. The history fields are instantaneous :!: Therefore, the time assigned to the time-averaged fields is always at the middle of the time-averaged window. Instantaneous diagnostic terms do not really make much sense. I don't see why you need history fields at the same time as the time-averaged fields. You could have NHIS=NDIA/2, then the time records will be at the same time. Notice that NDIA has to be an even number, so the division by two is exact and an integer number.

LiuZHQ
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Re: Is there any tools to output the "dia" at the time of "h

#3 Post by LiuZHQ » Wed Sep 07, 2011 2:03 am

arango wrote:Well, the diagnostic terms involve a time-integral like the averages files. I usually recommend to have NAVG=NDIA to facilitate computing budgets and fluxes. The history fields are instantaneous :!: Therefore, the time assigned to the time-averaged fields is always at the middle of the time-averaged window. Instantaneous diagnostic terms do not really make much sense. I don't see why you need history fields at the same time as the time-averaged fields. You could have NHIS=NDIA/2, then the time records will be at the same time. Notice that NDIA has to be an even number, so the division by two is exact and an integer number.

Thanks so much for your reply, arango.
In fact, I just try to take a look at the assosicate momentum terms related to some non-steady state cases, for example, waves or tides, and the acceleration is expected to be important. That's why instantaneous diagnostic terms make sense from my point of view.
You provide a possible solution to my problem. However, it can just shift the time of "DIA" files to the "HIS" files', the terms in this DIA file should still be averaged during the time we defined, and it is not exactly what I needed or the "instantaneous terms".
Am I right?

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Re: Is there any tools to output the "dia" at the time of "h

#4 Post by leonjld » Wed Sep 07, 2011 4:37 pm

You can calculate any momentum terms from the his files by yourself using e.g. MATLAB. The ROMS dia files are averaged fields and are used for diagnosis purposes only.

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Re: Is there any tools to output the "dia" at the time of "h

#5 Post by kate » Wed Sep 07, 2011 4:40 pm

I assumed the original poster was asking if anyone already had the matlab scripts for doing this. Didn't someone say they'd done it?

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Re: Is there any tools to output the "dia" at the time of "h

#6 Post by LiuZHQ » Thu Sep 08, 2011 1:59 am

leonjld and kate, thanks for your reply.
kate was right, and to me, it looks better if we can find some method to output it directly from the model. His file can not give us the information related to time, which means we can not obtain the terms expressed as parcial something parcial time.
I'd better check the code and find some solution.
If anyone can provide that kind of tools, it will be highly appreciated.

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Re: Is there any tools to output the "dia" at the time of "h

#7 Post by leonjld » Thu Sep 08, 2011 4:05 am

i see what you need now. I think one way to do it is to set:

NTSDIA == 1 ! Starting diagnostics time-step

to another value. If NDIA == 72, for example, you can set NTSDIA to 71, or maybe even 72. I haven't used that, so I can be wrong. Kate and Arango can confirm the meaning of NTSDIA.

LiuZHQ wrote:leonjld and kate, thanks for your reply.
kate was right, and to me, it looks better if we can find some method to output it directly from the model. His file can not give us the information related to time, which means we can not obtain the terms expressed as parcial something parcial time.
I'd better check the code and find some solution.
If anyone can provide that kind of tools, it will be highly appreciated.

LiuZHQ
Posts: 44
Joined: Mon Apr 06, 2009 5:12 pm
Location: The Hong Kong University of Sci&Tech

Re: Is there any tools to output the "dia" at the time of "h

#8 Post by LiuZHQ » Thu Sep 08, 2011 7:13 am

leonjld, thanks for your suggestion, and I'll check it.

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