Question

When using a recording depth finder in the open ocean, what phenomena is most likely to produce a continuous trace that may not be from the actual ocean bottom?

A) Multiple returns reflected from the bottom to the surface and to the bottom again
B) Echoes from schools of fish
C) Poor placement of the transducer on the hull
D) Echoes from a deep scattering layer

Answer 1

Echoes from a deep scattering layer are the most likely cause of continuous traces on a depth finder's recording in the open ocean, potentially misleading the actual position of the ocean bottom.

Step-by-step explanation:

When using a recording depth finder in the open ocean, the phenomena most likely to produce a continuous trace that may not be from the actual ocean bottom is echoes from a deep scattering layer. This layer is composed of marine organisms such as plankton and small fish, which can reflect the sonar signals back to the transducer. This ultimately gives a false indication of the sea floor's location. While other options like multiple returns and poor transducer placement could also affect readings, it's the deep scattering layer that is known to consistently produce misleading continuous traces on sonar equipment.

There are limits to the sonar system's time resolution when detecting the size and shape of objects. The resolution depends on the ability of the system to distinguish between two signals arriving at slightly different times. If objects are too close together, the sonar system may not be able to resolve them as separate entities.