How to measure the Currents Coastal of Ulsan?

1. Where is Ulsan

Ulsan is a cosmopolitan industrial city in Southeastern South Korea. It nestles on the coastline of the East Sea, or as others call it, Sea of Japan. The landscape joins the power of the sea to the might of industry.

The city is famous for having huge industrial complexes, especially in the petrochemical and automotive industries. The manufacturing facilities of the Hyundai Motor Company are a large part of Ulsan's identity. These industrial areas bustle with life as high-rise refineries and factories bring fame to Ulsan on the world economic map.

But Ulsan also has its softer side. Down on the coasts, there are lovely beaches and parks to walk around: for instance, Taehwagang National Garden provides a nice green oasis in this area of a city within a lot of industry. The local people are mainly composed of factory workers and a few service area workers pertaining to the variety of fields making up this city's economy.

The East Sea off Ulsan is cold and very rich in marine resources. It forms a habitat for a wide variety of fish species such as mackerel, squid, and pollock. The seaweed beds are extensive, and they play an important role in the local marine ecosystem. The coastal waters also have a significant impact on the local climate. The sea breezes bring a refreshing touch to the city, especially during the hot summer months.

2. What is the situation of the coastal currents around Ulsan?

The coastal currents around Ulsan are determined by several factors. The major ocean currents in the East Sea are of great importance. In this area, one can find both the Tsushima Current, which is a warm-water current, and the Liman Current, which is a cold-water current. The Tsushima Current generally flows northward, carrying relatively warm and nutrient-rich water. The Liman Current moves southward and is colder. Their meeting point near Ulsan creates a complex pattern of water movement.

Tidal currents also exert a strong influence. There is a large tidal range at Ulsan, and due to the ebb and flow of the tides, dynamic current patterns are created. The shape of the coastline and the underwater topography play an important part. These currents can diverge, converge, or form eddies, depending on the underwater topography of reefs, shoals, and channels. For instance, a submerged reef may deflect the current and, by doing so, its speed and direction are changed. Besides, the wind pattern, especially the strong winds blowing across the East Sea, drives surface currents and affects the mixing of different layers.

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

Surface Drifting Buoy Method: A surface - drifting buoy can be used to track the surface current. The buoy is released into the water and its movement is monitored over time using GPS or other tracking systems. However, this method has limitations. It only provides information about the surface current and can be affected by wind and waves. For instance, if there is a strong on-shore wind, it may push the buoy towards the shore, which might reflect an improper direction of the current actually in occurrence.

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

Acoustic Doppler Current Profiler (ADCP) Method: The ADCP current meter is a more advanced and efficient means of measuring the coastal currents. ADCPs emit acoustic signals into the water and measure the Doppler shift of the reflected signals to calculate the velocity of water at different depths. This gives a far better profile of the current right from the surface down to the seabed. Being less affected by surface disturbances, ADCPs can continuously work for long periods and give a much better picture of the structure of the current.

4. How do the ADCPs using the Doppler principle work?

The operation of ADCPs is based on the Doppler principle. They emit high-frequency acoustic pulses into the water. When these pulses encounter moving particles of water, their reflected frequency is different from that which was emitted. When water particles are moving toward the ADCP profiler, then the reflected signal frequency is higher compared to the emitted signal frequency, and vice versa for when they are moving away.

ADCP meter is outfitted with multiple transducers, each emitting and receiving at various angles. By observing the various directions and depths at which these signals are shifted through Doppler, this device will then work out the three-dimensional velocities of water. In this way, it shall estimate horizontal and vertical components of velocity, therefore enabling quite in-depth information on structure and behavior of current.

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

For high-quality measurement of coastal currents around Ulsan, the equipment should be made of reliable materials. The harsh marine environment includes cold water, saltwater, and even storms that may hit it. The casing should be hard enough to endure these conditions. The size of the equipment should be small to allow for easy deployment and retrieval, especially in such a complex coastal landscape.

A lightweight design is preferable as it makes the equipment more manageable during installation and maintenance. Low power consumption is crucial for long - term and autonomous operation. Cost - effectiveness is also important to enable large - scale measurements.

The casing of ADCPs is preferred to be made of Titanium alloy. Titanium alloy has excellent corrosion resistance, which is very vital as it has to resist the corrosive action of seawater. It is also strong and durable to bear the pressure of water at different depth. Its lightweight nature is more convenient for various deployment methods.

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

When selecting equipment for measuring currents around Ulsan, the main use needs to be considered first: If its purpose is in navigation at a vessel or in conducting short-term research, one may opt for the in-vessel mountable variety of an Acoustic Doppler Current Profiler - ADCP flow meter that gives current info in real-time while aboard the voyage.

For measurements near the seabed, such as studying sediment transport or benthic ecology, a bottom-mounted ADCP is preferable. 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.

Regarding the frequency of ADCPs, for water depths up to 70m, a 600kHz ADCP is a good choice. For depths up to 110m, a 300kHz ADCP is more appropriate. And for deeper waters that might be found near Ulsan, such as areas with a depth over 1000m, a 75kHz ADCP is recommended.

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.