http://www.udel.edu/PR/UDaily/2008/jul/interns070607.html

Foreward...

In Jun-Aug 2007, I participated in an internship with Andreas Münchow at the University of Delaware's program in Physical Ocean Science and Engineering.

The internship consisted of refurbishing some of my advisor's old FORTRAN code to analyze some recently collected data from the R/V Hugh Sharp. The code parsed the raw binary stream and performed its own statistical analysis on it. It was combined with a series of shell scripts to further automate the process. Unfortunately, the code had been left disused for many years, and was tailored to a specific cruise. As a result, I was able to learn FORTRAN and increase my skills with shell scripting by going through the code and making it generic. This further involved reading documentation and papers about the workings of the ADCP, so that I could understand, and in some cases, improve the analysis of the raw data.

The resulting documentation can be found here (410K *.pdf)


Analysis of Tides

Orientation of the Main Tidal Component

Recalculating the velocity profiles from the raw binary stream allowed us to use more or less stringent statistical techniques than the proprietary analysis software would have otherwise applied.





Phase of the Tidal Ellipse

For example, default values for data being thrown out by the program could be increased in some cases to salvage data that would have otherwise been unavailable. Similarly, default thresholds for an ADCP used in say, an icebreaker, could be relaxed for the much calmer Delaware Bay.





Semi-major Axis of the Tidal Ellipse

After that, I was amazed to find out that a combination of Fourier analysis and knowledge of astronomy could be used to extract the tides from the velocity profiles, and furthermore, that what was left over, the mean outflow, could provide an important boundary condition on the dynamics of the Bay itself.







Subtidal Flow

Subtidal Outflow Perpendicular to Transect
I have since learned that it is a visualization faux pas to use the rainbow color map. However, at the time I felt very clever in finding a way to register the 3-D data onto a 2-D plane, and then to display the data in a simple way. The result is the Outward- and Across channel flow images shown here. They are shown next to a lat/long ship-track plotted with the CTD locations of the cruise. It is easy to see the two lobes of the tidal ellipses in the first two images, and the floating, fresh, and fleeing mass of water flowing out of the bay in the second.


Across-Channel Flow









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