Acoustic Doppler Current Profiler (ADCP)
|ADCP Personal account: The Value of Petroleum Jelly and Chili Powder|
By Andrea Baird (June 2004)
Barnacles can transform an ADCP from a useful piece of equipment into a
useless piece of plastic in just a few days. If animals grow on the transducer heads, the flat plates on top of the instrument that transmit and receive sound, the ADCP can't send out pings or collect any data. Many scientists coat every part of the instrument except the transducers with paint that chemically repels barnacles and other encrusting animals. For scientists who don't want to use anti-fouling paints or have rented their equipment, however, there are some low-tech alternatives.
While working as a biologist at Mote Marine Laboratory in Sarasota, Florida, I was part of a project studying water currents in a small bay next to a power plant. Senior Scientist Jim Culter and I put several rented ADCP instruments out on the bottom of the bay hoping that they data they collected would tell us whether runoff water from the plant was flowing into the bay.
We needed the instruments to collect data for several weeks, but we knew from experience that they would be covered in barnacles after the first two or three days - unless we found a way to keep them off. A representative from RD Instruments, the company that owned the ADCPs, suggested a home-brewed barnacle repellent made of petroleum jelly and chili powder. So we mixed up a batch, wrapped the bases of the profilers tightly with garbage bags and electrical tape, and smeared the red goo all over the transducer heads. It made an awful mess (and an awful smell), but it worked.
Rumor has it that diaper rash creams containing zinc oxide also keep barnacles from settling. The slime will come off in time, though, so the meters have to be
periodically brought back to the surface and re-coated.
Example of data
ADCP data from the Martha’s Vineyard Coastal Observatory on 1 Jan. 2004. Getting this data into an understandable format is pretty complicated. Software programs like WinADCP can take the raw binary data from the ADCP and combine it with GPS coordinates to come up with preliminary current graphs and tables. Frank Bahr processes the numbers again later to turn to make contour and current vector maps. It takes a couple of weeks to get the data from a thirty-day cruise into its final format. [View ADCP data]
The Performance of ADCP-Derived Directional Wave Spectra
and Comparison with Other Independent Measurements [PDF Version]
B. Strong and B. Brumley, Dr. E.A. Terray and Gregory W. Stone
Evaluation of Wave Measurements with an Acoustic Doppler Current Profiler [PDF Version]
K. Rørbæk, H. Andersen
Horizontal ADCP for Remote Mapping of Currents
Long-Range Current Profiling from Moving Vessels [Word Document]
Max Edelhauser, Fran Rowe and Frank Kelly
Measuring Waves and Currents with an Upward-Looking ADCP [Word Document]
Eugene A. Terray, Blair H. Brumley and Brandon Strong