3. Biosonics echosounder: Echos are sound waves which bounce back to their source after they hit an object. This echosounder works by the same principal, but can detect bio/living things. The biosonics echosounder produces sound pulses in three different frequencies and wavelengths. With the help of the reflected sound waves from the objects that the sound pulses hit, it can determine the size of organisms. The amazing thing about the biosonic echosounder is that it can sense even the microscopic type of zooplankton which are not visible with the naked eye. As a biology note: there are also bigger, macroscopic size zooplankton, such as jelly fish and krill. So, with the help of different wavelengths produced by the biosonic echosounder, we can identify living creatures of the ocean from the size of microorganisms to macroorganisms - zooplankton to whales.
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| 3 Frequency Biosonics Echosounder. Photo by Murray Leslie |
Q: Why do we need the biosonics echosounder to detect visible fishes instead of just implementing a video camera?
A: Because Folger Deep does not provide clear visibility. And also, biosonics echosounder allows us to image the entire water column at once 100 meters.
4. ADCP: Another wonderful abbreviation; here, the key letters are D and C.
D stands for the Doppler (ambulance) effect. If you stand still at a point while an ambulance passes, the sound of the siren that you hear as the ambulance approaches is different than the sound you hear as it gets farther away. As it approaches, the ambulance itself and the sound waves it produces are both coming towards you. The ambulance helps to carry the sound waves, increasing the frequency of the sound you hear when compared it to its original source. However, once the ambulance passes it carries sound waves with it. As the ambulance goes away from you the frequency of the sound waves decreases. Therefore, you hear frequencies increasing as it approaches and decreasing once it passes. This is called Doppler effect (Doppler observed it, so it is named after him).
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| ADCP - Acoustic Doppler Current Profiler |
Q: What frequency do the ambulance drivers hear?
The C in ADCP is the current, measured as the difference between the sound pulses which are sent and those which are received, just as in the ambulance example. The biggest difference is that sound moves faster in water than in air.
ADCP stands for Acoustic Doppler Current Profiler; it creates the profile of water currents.
The Folger Deep platform has been successfully operating in Folger Passage since August, 2009. But, once a year it needs something...cleaning!! So, the Folger Deep platform was taken out and cleaned by good hands. After the cleaning and a few calibrations the platform was placed back into the water.
Goksenin Sen
Marine Educator
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