wave data processing

hello,

does anyone have a matlab routine to process wave data, surveyed by the aquadopp profiler???

best regards,

rodrigo.

oceanography academic,
   Itajai - SC - Brasil

Hello Rodrigo-

I suggest checking out the forum topic "Matlab tools for PUV".

http://www.nortek-as.com/cgi-bin....f=5;t=7

Here you will find a link to the Nortek USA web page that provides a primer for measuring waves with PUV type instruments (Aquadopp Profiler).

You are welcome to ask questions here if there is anything you do not understand.

Cheers,
Torstein

Hello Torstein,

I found the routines and now the doubt is another!!!
In one of the routines, wds.m, a parameter named "nF" (nominal number of output frequencies) is asked. What is this parameter and how can i found it?  

there goes wds.m attached...

thank you,
Rodrigo

Hello Rodrigo-

This suite of Matlab functions was written by Lee Gordon is the US, so I am not intimately familiar with the code.

However after looking through it I concluded that the variable nF refers to the number of frequency bands.  I learned this by looking in the function logavg.m.

regards,
Torstein

Hello Torstein,

My doubt is how can i found this bands?
Where i look for it?
Is it related with the frequency i am working ?

thank you for your patience,

rodrigo

Dear Torstein,

I'm processing wave using Matlab routines by Lee Gordon, and maybe you can help me.

The WDS.M routine need ot enter with a Ndir parameter, that is 'north component'. If I left it 0, the results comes with negative directions. I see it is a correction, but how to define it?

Thanks,

Guto

Hello Guto,

Tough to clearly say... it has been almost 3 years since I looked at Lee's code.  However my best guess is that the Ndir is an offset (for example, local magnetic deviation). See the two lines copied below.

Dir=57.296*atan2(Cpu,Cpv)+Ndir;
Dir=mod(Dir+180,360)-180;


The second line looks like a switch in direction "to" to direciton "from".   The negative directions likely come from not forcing the directions positive. This can be done by just adding 360 to the directions that are negative. The following should fix this:

ii = find(Dir < 0);
Dir(ii) = Dir(ii) + 360;


Kind regards,
Torstein

Dear Torstein,

Thanks... your're right! The Ndir refers to magnetic declination.

After some experimentations and ploting the results in geographical coordinate polar plot, the negative directions in matter of fact are rigth in the sense of turning anti-clockwise from the North. -45 = 325 = NW   " />'>

But just advise that the routine as it is give the waves 'to', not 'from'.

Best regards,

Guto