The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Development of acoustic techniques for the remote sensing of ocean velocity has been progressing at Scripps for the past 34 years. While many scientifically productive systems have been created, there have also been numerous technical surprises and well explored dead-ends. Here, the development of both coherent and incoherent backscatter systems at SIO is reviewed, with an emphasis on the real-world...
The excellent space-time resolution of pure coherent Doppler system has led many scientists to select this processing technique to solve his or her measurement problem. There is nothing in the acoustic Doppler world that can beat the information content of a pure coherent system. The high vertical and temporal resolution give an instantaneous picture of the flow field with photographic clarity; slow...
Under ideal conditions, pulse-to-pulse coherent Doppler sonar can measure profiles of water velocity with unparalleled accuracy and resolution. However, this technique is limited in application by the occurrence of range and, more critically, speed ambiguities. A simple way to deal with speed ambiguities is to invert velocities using time history or prior knowledge of the flow structure, but these...
By transmitting an acoustic pulse of several distinct frequencies we have improved the data quality of the Doppler current measurements significantly without increasing the power drain, measurement time, or the pulse length.
Doppler profilers measure velocity components along the axis of three or four diverging acoustic beams. Instrument firmware combines these measured components to determine the underlying three component velocity profile relative to the instrument. By correcting for instrument attitude and velocity, these instrument referenced velocities are transformed into a "world" coordinate system and...
A solution to measuring near-surface currents via a single-cell acoustic Doppler current meter with horizontally oriented acoustic beams positioned very close to the sea surface is presented. The current meter was deployed on a surface buoy on the 25 m isobath of the west Florida continental shelf. Near-surface velocity observations from the current meter (1.1 m depth) are compared to estimates from...
The combination of attenuation measurement with acoustic travel-time current measurement along a common path has produced a new acoustic sensor of suspended particles, the acoustic transmissometer (AT). The AT has been deployed in the OASIS experiment, a particle-measuring experiment to determine suspended particle properties resulting from turbulence and current near the seabed. Acoustic transmission...
Ocean currents all over the globe contribute significantly to the state of the world climate. Knowledge of how they vary with time can provide a useful information on future states of the climate system. While satellites provide excellent spatial coverage, they measure only surface currents. To determine mass- and heatfluxes and their change over time accurately requires regular and repeat measurement...
We consider the potential for making current measurements from gliders, and present data from a deployment in early 2007 of 1000 m Slocum electric gliders in the North West Mediterranean Sea. Three types of current measurement are considered. First, by comparing the difference between successive GPS positions, obtained when the glider surfaces, and dead-reckoned displacements when the glider is submerged,...
A long-term real time sea bed morphology monitoring system has been established on the middle continental shelf in the South Atlantic Bight. This constitutes part of the Southeast Coastal Ocean Observing System (SEACOOS) and now supports a project that focuses on studying material exchange processes in permeable sediments in response to large scale atmospheric and oceanic forcing. In particular the...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.