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Study links changing winds to warming in Pacific #Ocean | Santa Cruz News - KSBW Home http://buff.ly/1quFmBq

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Measuring Ocean Currents
Measuring currents is a fundamental practice of physical oceanographers. By determining how ocean waters move, scientists can determine how organisms, nutrients and other biological and chemical constituents are transported throughout the ocean [1].  Other application are determining pollutant transport, tidal flows, sediment transports.
How do we measure speed of water  in ocean? 
Generally flow measurement for ocean water is done by deploying measuring instrument at seabed. Duration of deployment can vary from couple of hours to few days to even months and years. ADCP is one such instrument.
What is ADCP and why do we use it?
Acoustic Doppler Current Profiler (ADCP), is a measuring instrument. Researchers use the instrument to measure how fast water is moving across an entire water column. ADCP when installed at seafloor can measure flow speed and direction from bottom to surface at regular intervals.  Instrument can also be installed at bottom of a ship, or bridge pilings in rivers and sea.
How does it work?
ADCP uses Doppler effect to measure flow velocity in water.  ADCP transmit “pings ” of sound at a constant frequency into the water.  The pings are so highly pitched that human and even dolphins cannot hear them.  As sound waves travel they reflect back to instrument off particles suspended in moving water. Sound waves bounced back from a particle moving away from instruments axis have lower frequency when they return.  Particle moving towards the instrument send back higher frequency waves.  The difference in frequency between the sound waves instrument sends and the waves received is called the Doppler shift. Instrument uses this shift to calculate how fast the particle and water moves.
ADCP deployment  platform  and data?
ADCP that are bottom mounted need anchor to keep them on the bottom of sea. ADCP that is ship mounted need ship rack. The data from instrument can be stored in inbuilt memory or read instantly with help of connected computer.   
Water depth grater then 1m up to 1 km is measured with ADCP.
Recently  our research group conducted ADCP deployment in the South China Sea near the Bachok Marine Station, IOES, University of Malaya. Here is one video from the field deployment.  Instrument was deployed at 12 m depth.
 
References
[1] http://oceanexplorer.noaa.gov/technology/tools/acoust_doppler/acoust_doppler.html
[2] http://www.whoi.edu/science/instruments/

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Tiny #OceanPlastic May Be Cleaning our Seas http://buff.ly/1lHGRjk | Ocean Minds Where Fish Get Their News!

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Belugas hear underwater sounds in the range 4-150 kHz. The link is to new open-access paper.

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Never-Seen-Before Whale Washes Up on New Zealand Shore http://b4in.org/c35y

A species of beaked whale known previously only from bone fragments has been seen for the first time after a mother and calf recently washed up on a New Zealand shoreline. Called the spade-toothed beaked whale, the species has understandably been hailed as the world's rarest whale.

While it's unfortunate that the first sighting of the animal comes with such a tragic scene, scientists are thrilled at the chance to learn more about this mysterious species. Until this stranding, it was unclear that the species even still existed.

“This is the first time a spade-toothed beaked whale has been seen as a complete specimen, and we were lucky enough to find two of them. It's incredible to think that, until recently, such a large animal was concealed in the South Pacific Ocean and shows how little we know about ocean biodiversity,” said lead scientist Dr. Rochelle Constantine.

Beaked whales as a group are among the least understood mammals in the world because of their elusive deep-sea, open ocean lifestyle.

None of the 21 recognized species are well known to the public; In fact, only a few of them are well known to biologists. They are characterized by their elongated beaks and their tusks, and are capable of diving to extreme depths: to over 1,000 fathoms.

More http://b4in.org/c35y
Photo

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Antarctic Circumpolar Current Carries 20% More Water Than We Thought http://buff.ly/1evxIWJ 

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Sea Ice Data at Your Digital Fingertips: Alaska Sea Ice History Since 1860!
http://www.oceanminds.com/sea-ice-data-online-atlas/ 

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Scientists Call for New Stewardship of the Deep Ocean
http://buff.ly/1dJfGQm 

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