[Acoustics] ADCP velocity data processing and countour plots

[Smith, Brennan T.]

Our procedure for doing what you describe goes something this:

1.  Process the binary data files in WinRiver with appropriate settings
to produce an ASCII-Out files
2.  Parse the ASCII-Out files with Perl scripts that:
(a) Transform (lat,lon) to plane coordinates (UTM, State Plane, or local
oblique Mercator)
(b) Extract the bottom track displacements as alternative horizontal
positioning for each ensemble
(c) Output the water track ensembles in a structured 2D "IJ-ordered"
data set with the variables of interest (Evel, Nvel, UpVel, ErrVel,
dB[1-4], Corr[1-4], ...), ensuring that data below the bottom is marked
as such.  The ADCP transect files already have an inherent 2D structure
where I=#of bins and J=# of ensembles.  If your contouring software can
handle blanking of regions based on input values or based on an
auxiliary field of data (i.e. the mark bad below bottom field), then no
additional gridding or triangulation is required.  Of course, your track
has to be reasonably linear for this to be physically meaningful.
(d) Output the bottom track readings as a 1D "I-ordered " data set so
that you have a bottom boundary that corresponds to your water track
data
3.  Import the water track structured data sets into your software and
contour based on cell average values or nodes.  We use a commercial
fluid dynamics visualization package for this (E-mail if you want
specifics) but the freely available 'grdcontour' and 'grdimage' tools
(part of the Generic Mapping Tools http://gmt.soest.hawaii.edu/) also do
a very good job with this.
4. Import the bottom track data set and plot as poly line or discrete
points to represent the bottom below the water track data.

E-mail if you would like to discuss further or get scripts to use as a
starting point.  What I have is not very user-friendly, but it is
automated.  Hope this helps.

Brennan T. Smith, Ph.D., P.E.
Tennessee Valley Authority
River Operations
400 W. Summit Hill, WT 10D-K
Knoxville, Tennessee  37902
865-632-3875 Voice
865-632-4255 Fax
btsmith at tva.gov
 
  

-----Original Message-----
From: acoustics-bounces at simon.er.usgs.gov
[mailto:acoustics-bounces at simon.er.usgs.gov] On Behalf Of Jonathon Mann
Sent: Wednesday, December 01, 2004 4:00 PM
To: acoustics at simon.er.usgs.gov
Subject: [Acoustics] ADCP velocity data processing and countour plots


Hello,

I am using velocity data from a broadband ADCP to quantify flow fields 
and velocity distributions in a river. I am looking for resources that 
will enable me to more easily produce contour plots of equal velocity 
lines. Transferring data from WinRiver and WinADCP still requires a lot 
of data manipulation before producing XYZ formatted data needed for 
contour plotting. And doing this for many transects can be labor 
intensive. Is anyone on the list also doing this type of work and 
willing to provide some insight on their methods?

Thanks,
Jonathon Mann, P.E.
Hydraulic Engineer
NOAA Fisheries
Santa Rosa, CA

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