Re: Measuring vertical velocity with ADCP

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Re: Measuring vertical velocity with ADCP

Posted by lhancke at June 19. 2012

Good day

Could you give me some advise on measuring the vertical velocity component with ADCP technology? Until now I have only been interested in the horizontal components. I looked at data that we collected in the past with a 600KhZ AWAC and see a lot of noise in the vertical component with some unrealistic measurements (attached).

I have also read in the forum that measuring w velocity with ship's ADCP  is problematic.

What is the best instrument and sampling protocol to use to accurately measure velocity? 

Regards

Lisa

 

Attachments

Re: Measuring vertical velocity with ADCP

Posted by Jonas Røstad at June 20. 2012
Good day Lisa,
 
The screen shot attached is too small to analyze. I would very much like to have access to the raw data to understand this better. Is it possible for you to upload it to ftp://ftp.nortek.no/Incoming/ ?
 
Best regards
Jonas Røstad

Re: Measuring vertical velocity with ADCP

Posted by lhancke at June 22. 2012

Hi Jonas

I uploaded the file to your ftp site under folder 'hancke'.

Just a few details about the deployment -

The 600 kHz AWAC was deployed in 80m of water on a subsurface float (instrument depth 40m). Currents were collected every 30 mins. The region is known for strong currents and located in an upwelling cell, so we expect to see an increase in the vertical velocity component with upwelling/downwelling events.

I look forward to your reply.

Regards

Lisa

Re: Measuring vertical velocity with ADCP

Posted by Jonas Røstad at June 22. 2012
Hi Lisa,
 
We have looked at the data and actually think they seems quite good. How large vertical velocities was expected at this site? Should there be both upwelling and downwelling events? 
 
Please advice.
 
Best regards
Jonas Røstad
 
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