[Coral-List] Doppler Velocity Meter & Corals: Coral-List Digest, Vol 26, Issue 18

Curt Storlazzi cstorlazzi at usgs.gov
Fri Oct 15 14:56:35 EDT 2010


Dana (and colleagues),

We've used a range of instrument, from electromagnetic single-point  
current meters and single-point acoustic doppler velocimeters to  
acoustic doppler current profilers made by such companies at Marsh- 
McBirney, Sontek, RDI, and Nortek. For the record, I don't think  
anyone really uses electromagnetic current meters any more, for the  
instrument itself disturbs the flow being measured, so pretty much  
everyone has gone to acoustics, which also provide some information on  
the density of material in the water column (acoustic backscatter),  
which is useful for providing insight into sediment, larval, etc  
dynamics when calibrated with data from other sensors.

In terms of using a single-point acoustic doppler velocimeter versus  
an acoustic doppler current profiler, it really depends on what you're  
looking to measure. Single-point acoustic doppler velocimeter provide  
the most precise x-y-z (or, with a compass and tilt sensor u-v-w)  
currents at one point, and can often sample at much higher rates (~10  
Hz) than acoustic doppler current profilers (~1 Hz), thus allowing you  
to make measurements of turbulence and other high-frequency processes.  
Acoustic doppler current profilers, while not providing accurate z (or  
w, heading towards/away from the transducers) currents and lower- 
resolution x-y (u-v, flow perpendicular to the transducers) than  
acoustic doppler velocimeters, do provide a profile of x-y (u-v) at  
set ranges away from the transducer, allowing one to examine the  
variability in flow structure (and acoustic backscatter) over some  
distance through the water column.

In terms of manufacturers, it's all depends on what you want- ability  
to integrate external sensors, broadband capability, ease of use,  
etc.  I'm guessing you'd get 10 different answers from 10 different  
folks; I happy to chat more about this offline, if desired.

Curt

ciao.....
_______________________
Curt Storlazzi, Ph.D.
U.S. Geological Survey
Pacific Coastal and Marine Science Center
400 Natural Bridges Drive
Santa Cruz, CA  95060
(831) 427-4721 phone
(831) 427-4748 fax

Staff web page:
http://walrus.wr.usgs.gov/staff/cstorlazzi/

On Oct 15, 2010, at 9:00 AM, coral-list-request at coral.aoml.noaa.gov  
wrote:

> ------------------------------
>
> Message: 4
> Date: Thu, 14 Oct 2010 18:06:40 -0400
> From: riddlelabs at aol.com
> Subject: [Coral-List] Doppler Velocity Meter & Corals
> To: coral-list at coral.aoml.noaa.gov
> Message-ID: <8CD3A03364188FB-9DC-5FBC at webmail-d095.sysops.aol.com>
> Content-Type: text/plain; charset="us-ascii"
>
>
>
> Aloha,
>
> Is anyone using a doppler water velocity meter (such as Sontek?).  
> I'm hoping to upgrade from my Faraday-based velocity meter and would  
> greatly appreciate ANY input.
> Sontek recommends a 10mHz ADP doppler for my applications (field and  
> some lab work).
>
> Thanks,
> Dana
>
>
>
>
> ------------------------------




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