Utilizing Subsea Cables to Monitor Ocean Currents in the Atlantic

Measuring ocean currents with undersea cables

The world’s oceans are vast and dynamic, with complex currents that play a critical role in regulating global climate, transporting nutrients, and supporting marine ecosystems. Understanding these currents is critical for a wide range of applications, from weather forecasting and climate modeling to maritime navigation and offshore operations. One ingenious method of measuring ocean currents is the use of undersea cables, which use the electromagnetic properties of seawater to provide valuable insights into the behavior of these oceanic currents.

The principle of electromagnetic induction

At the heart of this technology is the principle of electromagnetic induction, first described by the renowned scientist Michael Faraday in the 19th century. When a conductive material, such as seawater, moves through a magnetic field, it generates an electric current. This current, in turn, produces a secondary magnetic field that can be detected and measured. By strategically placing undersea cables across ocean currents, researchers can harness this electromagnetic phenomenon to gain a comprehensive understanding of the speed, direction, and other characteristics of the flowing water.
The cables used in this application are typically made of copper or other conductive materials and are buried under the seabed to ensure that they are not disturbed by surface waves or ship traffic. When ocean currents pass over these cables, the movement of the conductive seawater induces a small electrical current in the cables. By measuring the voltage and current generated, scientists can calculate the speed and direction of the currents, providing critical data for a wide range of applications.

Benefits of submarine cable measurements

One of the main advantages of using submarine cables to measure ocean currents is the ability to obtain continuous, long-term data. Unlike traditional methods such as ship-mounted instruments or drifting buoys, the cables can provide a constant stream of information, allowing researchers to detect and analyze subtle changes in current patterns over time. This temporal resolution is particularly valuable for studying the effects of climate change, seasonal variations, and other long-term trends.
In addition, cable placement can be strategically chosen to target specific regions of interest, such as critical choke points or areas of high commercial or ecological importance. This flexibility allows researchers to collect targeted data that can inform decision-making in a wide range of areas, from marine transportation and offshore energy development to fisheries management and coastal resilience planning.

Challenges and Progress

While the use of submarine cables to measure ocean currents is a robust and reliable technique, it is not without its challenges. The harsh marine environment, with its strong currents, high pressures, and potential for biofouling, can pose significant obstacles to the longevity and accuracy of cable-based systems. Researchers and engineers are constantly working to develop more robust and sophisticated technologies to overcome these challenges.
One such advancement is the integration of fiber optic cables, which can provide even more accurate measurements of flow velocity and direction. By using the Doppler effect to analyze the shift in frequency of light passing through the cables, these systems can provide high-resolution data with minimal interference from electromagnetic noise or other environmental factors.

As our understanding of ocean dynamics continues to evolve, the role of subsea cable-based measurement systems will undoubtedly grow in importance. These innovative technologies, combined with advances in data analysis and modeling, are poised to revolutionize our ability to monitor and manage the world’s oceans, ultimately contributing to more sustainable and informed decision-making for the benefit of the planet and its inhabitants.

FAQs

Here are 5-7 questions and answers about measuring ocean currents from cables:

What mechanism is used to measure ocean currents from cables?

The mechanism used to measure ocean currents from cables is called an electromagnetic flow meter or electromagnetic current meter. This device measures the voltage induced by the flow of seawater through the earth’s magnetic field, which is proportional to the speed of the water flow.

How do electromagnetic current meters work?

Electromagnetic current meters have two metal electrodes that are placed a known distance apart on the seafloor cable. As the seawater flows through the magnetic field, it induces a small voltage between the electrodes that is proportional to the speed of the current. By measuring this voltage, the speed of the ocean current can be determined.

What are the advantages of using cable-mounted current meters?

Cable-mounted current meters have several advantages over other current measurement techniques. They provide continuous long-term monitoring of currents without the need to deploy and recover instruments. The cables are already in place for other purposes like telecommunications or power transmission, so the current meters can be added at relatively low cost. Additionally, the measurements are taken directly in the water flow rather than being inferred from surface or subsurface observations.

How accurate are cable-based current measurements?

Cable-based current measurements can be quite accurate, typically within 1-2 cm/s for current speed and 5-10 degrees for current direction. The accuracy depends on factors like the cable design, electrode placement, and calibration of the electromagnetic flow meters. With proper installation and maintenance, cable-mounted current meters can provide high-quality data on ocean current variability over long time periods.

Where are cable-mounted current meters commonly used?

Cable-mounted current meters are often deployed in areas with strong and persistent ocean currents, such as in straits, channels, or along the continental shelf. They are particularly useful for monitoring currents in regions critical for submarine cable operations, marine renewable energy, or naval operations. Some well-known examples include the cables across the Strait of Gibraltar, the Tsushima Strait in East Asia, and the Gulf Stream off the eastern coast of the United States.