Ocean - Surf Zone Measurements
[II-A]
I want to make measurements in the ocean. [change]
My area of interest is the surf zone. [change]
Because of the highly variable flows in the surf zone, you probably would like to make velocity measurements as
quickly as possible. This suggests using one of our Acoustic Doppler Velocimeter (ADV)
family of instruments. There are three type of ADVs: the 16-MHz MicroADV,
the 10-MHz ADV and the 5-MHz ADVOcean Probe. Choosing
among these three is really a tradeoff between maximum resolution and maximum ruggedness.
The MicroADV boasts the best
resolution in space and time, but the ADVOcean Probe is far more rugged
for surf zone applications. The ADVOcean Probe can sample at a maximum of
25 Hz, has a sampling volume of just over two cubic centimeters, and is extremely
rugged. On the other hand, the MicroADV has a sampling volume of less
than one-tenth of a cubic centimeter, can sample at rates as high as 50 Hz, and can
operate in very shallow water (<10 cm), but is more susceptible to damage. The 10-MHz
ADV, particularly the field ruggedized version, is intermediate in resolution and
ruggedness.
Any of the ADV-type instruments can be deployed for
real-time operation using a cable, or autonomously as part of our Hydra package. ADVs can also be equipped
with a variety of external sensors, including compass/tilt, pressure (three types of
sensor possibilities), turbidity sensors, conductivity sensors, etc.
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Researchers
from Scripps Institution of Oceanography prepare an ADV for measurements in the surf zone
of a local San Diego beach. The ADV was deployed at low tide and left in place to study
the near-bed velocities in the surf and swash zones with the changing tides. The ADV's
sensor head is highlighted in the box to the left. |
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