How to measure the Coastal Currents of Yangyang?

1. Where is Yangyang?

Located on the eastern coast of the Korean Peninsula is the county of Yangyang, Gangwon-do, South Korea. This is a haven for nature lovers and tourists who want to see idyllic coastal scenery.

The area boasts an attractive coastline composed of sandy beaches, rocky shores, and several small bays and inlets. The general landscape in the county is a perfect combination of mountainous and sea elements. The population of the county is engaged with activities like fishing, agriculture, and other tourism-related services. The East Sea, which is Sea of Japan, lying next to Yangyang is a cold-water body with abundant marine life.

It provides a multitude of different fish species, shellfish, and seaweed. The cold - water environment supports species such as cod and sea urchins. Offshore waters, too, have a significant bearing on the local climate. They consist of warmed or cooled air masses, moderate temperatures, sea breezes, and conditions that are reflected in the overall weather patterns in the area.

2. What is the situation of the coastal currents near Yangyang?

The coastal currents off Yangyang depend on a lot of different things. It is necessary to mention the major ocean currents of the East Sea playing an important role in this process. In this area, a warm-water current interact. The Tsushima Current generally flows northward, with relatively warm and nutrient-rich water, whereas the Liman Current moves southward and is colder.

Tidal forces play a significant role as well. The area presents tides of great range, and the ebb and flow result in the development of intricate current patterns. The shape of the coastline and features underwater add to the variety of the currents. These include underwater ridges, shoals, and channels that may cause currents to change direction and speed. Besides, the wind patterns, in particular the strong winds that are common in the area, can drive surface currents and mix different layers of water.

3. How to observe the coastal water flow of Yangyang?

Surface Drifting Buoy Method: A surface - drifting buoy can be used to trace the surface current. It is then thrown into the water and its movement is tracked over a certain period of time, usually through GPS or other tracking devices. This method has several limitations. It reflects only the surface current and may be influenced by wind and waves. For instance, if a strong onshore wind happens to blow, the buoy may be pushed in toward the shore and give an inaccurate representation of the actual direction of the current.

Anchor-Boat Method: An anchored boat can be used for the measurement of current. Instruments are lowered into the water from the anchored boat to measure current at different depths. While this allows for more detailed depth-wise measurements, it also has drawbacks. The fixed position of a boat restricts the area of measurement, and it may not capture the full variability of the currents in a large coastal area.

ADCP Method: This is a more sophisticated and effective method for the measurement of the currents on coasts. ADCPs send acoustic signals into the water and measure the Doppler shift of the reflected signals to calculate water velocity at different depths. This gives a better profile of the current from the surface all the way to the seabed. Being less sensitive to surface disturbance, ADCPs are able to function for longer continuous periods with greater accuracy of the current structure.

4. How does the principle of Doppler apply to ADCPs?

ADCPs work on the basis of the Doppler effect. They emit high-frequency acoustic pulses into the water. In this process, when these pulses are in contact with moving water particles, a shift in the frequency of the reflected pulses occurs. If the water particles are moving towards the ADCP current meter, the frequency of the reflected signal is higher than the one emitted; if moving away, it will be lower.

The ADCP current profiler utilizes multiple symmetrical transducers to transmit and receive signals at different angles. From this, the device can work out the three-dimensional velocity of the water by analyzing the Doppler shifts from various directions and at a different depth. That is, the horizontal and vertical components of the velocity, thereby offering an insight into the current structure and behavior.

5. What is required for high - quality measurement of Yangyang coastal currents?

For high-quality measurement in the coastal currents near Yangyang, it is relevant that the equipment possesses appropriate materials. Because of the harsh marine environment, with cold water, saltwater, and eventual storms, casing needs to be durable. In addition, the size of the equipment should be small in order to easily deploy and retrieve in an area with complicated coastal land.

A light design is preferred since it will make the equipment more manageable during installation and maintenance. Low power consumption is necessary for long-term and autonomous operation. Cost-effectiveness will also enable large-scale measurements.

The casing of ADCPs is preferably made of titanium alloy. Titanium alloy has excellent corrosion resistance, which is very important for withstanding the corrosive impact of seawater. Besides, it is very strong and can bear up against the pressure of the water at different levels. Its lightweight nature makes it more convenient for various deployment methods.

6. How to Choose the right equipment for current measurement?

The purpose of use should first be considered in choosing the equipment for current measurement near Yangyang. If the measurement is for navigation of a vessel or short-term research, a ship-mounted ADCP flow meter may be suitable. It provides real-time current information during the voyage.

Measurements near the seabed, such as for studies on sediment transport or benthic ecology, should preferably be done using a bottom-mounted ADCP as it is able to capture the details of the near-bottom current. If long-term and wide-area monitoring of the coastal current is required, a buoy-type ADCP current profiler is ideal.

As for the choice of frequency, for water depth up to 70m, a good choice will be 600kHz ADCP. For up to 110m depth, it will be 300kHz ADCP. In deeper waters that might be found near Yangyang, with depths of over 1000m, one can apply a 75kHz ADCP.

There are well - known ADCP current meter brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also worth considering. It is made of all - titanium alloy material and offers an excellent cost - performance ratio. You can find more information on their website: https://china-sonar.com/.

Here is a table with some well known ADCP instrument brands and moels.