Measurement of Fraserburgh Coastal Currents

1. Where is Fraserburgh located?

Fraserburgh is a vibrant coastal town in Aberdeenshire, Scotland. It lies along the north east Scottish coastline facing the North Sea. The optimal location has bequeathed on it an historical and root-deep relationship with the sea that has shaped town growth and town way of life profoundly.

The town boasts a rich historical heritage that goes back centuries. It was originally a small fishing village. With the growth of the fishing industry and trade, it became a thriving and renowned port town. The buildings in Fraserburgh are a mix of old and new architecture. There are stone houses in the middle of the town with typical Scottish architecture. Houses are thick with solid walls, small windows, and steep pitches, and are a classic, timeless beauty. There are newer buildings in the harbor and on the main roads. These include modern shops, restaurants, and overnight accommodation facilities, both for the locals and the tourists all year round. The blend of the old - world ambiance with new comforts provides a fascinating and welcoming atmosphere.

The people living in Fraserburgh are close to the sea. Fishing has remained a conventional profession passed from generation to generation. Although the fishing industry has weathered numerous changes over the years, many local fishermen still set sail from the harbor. They bring back all manner of fish, such as cod, haddock, and mackerel. The harbor is not only a bustling hub for fishing operations but also a popular spot for locals and tourists to go on boat excursions. They can breathe fresh sea air, see seabirds soaring overhead, and enjoy the spectacular view of the North Sea.

The beaches and waters surrounding Fraserburgh are of crucial significance to the local ecosystem. The North Sea waters surrounding Fraserburgh are a highly diverse marine environment. The waters are home to a rich diversity of fish species, seals, and seabirds. The seabed is highly complex in terms of topography with sandy bottoms, scattered rocky outcrops, and underwater channels. These not only support a rich diversity of biodiversity but also play a significant role in the water circulation.

2. What is the State of the Coastal Currents Surrounding Fraserburgh?

The coastal currents surrounding Fraserburgh are regulated by a number of factors. Tidal forces are among the regulating factors. The North Sea experiences semi - diurnal tides, two high tides and two low tides in a day. Tidal range varies, and consequent tidal current speed can reach up to as much as 2-3 knots along certain places, especially around small river entrance mouths or within the regions marked by a distinctly defined coastal boundary. Sediment and nutrient-bearing water flows inwards towards the land during high tide, enriching local marine environment by providing feeding ground and habitat for marine organisms. At low tide, the water recedes and the intertidal zone is revealed. This zone teems with life, consisting of little crabs, sea anemones, and seaweed.

Wind also plays a role. Strong south - westerly winds may drive surface waters into the coast, making coastal currents more vigorous. The winds also produce waves that mix with the currents to give a more complex pattern of flow. Northerly winds will drive the water away from the shoreline. The shape of the coast line, including headlands and bays, and the nature of the area in question, causes the currents to converge and diverge in different areas. Sandbars under the water and outcrops of rocks further complicate current trends. These can act as channels or barriers, bending the flow of water and creating areas of still or turbulent water. Second, the fresh water entering from the small streams pouring into the sea off Fraserburgh can also shape the local flows. The freshwater, being denser than sea water, forms a top surface and is apt to drift offshore and combine with the tidal as well as the wind-generated flow.

3. Observing the Fraserburgh Coastal Water Flow: Methods

Surface Drifting Buoy Method

Surface drifting buoys are a simple but effective way of tracking the surface - level currents off Fraserburgh. Surface drifting buoys have GPS or satellite - based tracking equipment attached to them. Once they have been put into the sea, the surface currents carry them away. Scientists can track their path over a period of time. From the movement of the buoy, they can estimate the speed and direction of the surface waters. But this method is only used for the top few meters of the water column. It might not be actually representative of what's happening deeper in the water, where the currents could be different due to reasons like variations in temperature and salinity.

Moored Ship Method

In the moored ship method, a ship is moored at a point near Fraserburgh's coast. Then, the current measuring devices that are available like electromagnetic current meters are utilized. These instruments can measure the flow of water at different depths. They provide a good vertical profile of the direction and speed of the current. But this method is confined to a point. Also, the presence of the ship can have the capacity to disrupt the natural flow of water. The shape of the ship's hull and how it is anchored can create turbulence in the water, which will affect the accuracy of measurement.

Acoustic Doppler Current Profiler (ADCP) Technique

The ADCPs have revolutionized the measurement of coastal current close to Fraserburgh. They can measure the whole column of water from the surface down to the bed from a position in space utilizing sound waves for non-intrusive measurement of the water current. They emit acoustic pulses and measure the Doppler shift of the echo signals from suspended material in the water such as sediment, plankton, or minute bubbles. They can then calculate the current velocity at different depths. This gives a clear picture of the current structure and is best suited for studying the complex coastal current patterns off Fraserburgh.

4. How Do Doppler Principle-Based ADCPs Work?

ADCPs operate based on the Doppler effect. They send out high-frequency acoustic pulses into the water. As these pulses hit small particles in the water, like sediment, plankton, or bubbles, the particles reflect the acoustic signals back to the ADCP meter. If the particles are moving with the water flow, there will be a Doppler shift in the frequency of the backscattered signal compared to the transmitted signal. The Doppler shift is directly proportional to the velocity of the particles compared to the ADCP. Through the analysis of the Doppler shift at different depths in the water column, the ADCP flow meter can calculate the speed of the water at the different depths. Different transducers on the ADCP measure the velocity components in different directions. Using these, it is possible to calculate the three-dimensional velocity vector of the water current, giving a complete picture of the direction in which the water is moving.

5. What Is Needed for High-Quality Measurement of Fraserburgh Coastal Currents?

Equipment Material Reliability

To take precise measurement of the Fraserburgh coastal currents, the reliability of the equipment material is vital. The casing of the ADCP current profiler should be made of material that can withstand the severe North Sea marine environment. Titanium alloy would be an ideal choice. Its great strength can support it to withstand the impact of strong currents of water, potential impact by floating debris, and the corrosive condition of seawater. Its low elastic modulus guarantees that it is flexible, and that helps reduce damage caused by mechanical stress. Furthermore, its good corrosion resistance makes it possible to leave the ADCP in water for long-term observation without reducing in quality much.

Small, Light Weight, Low Power, and Low Cost

A small and light weight ADCP current meter is easier to install and operate. You can attach it to a small research boat, fix it to a buoy, or situate it on the seabed. It also causes less disruption to the natural water flow, leading to more accurate measurements. Low power consumption is essential in long-term autonomous monitoring, especially when battery - powered equipment is employed. A low-cost ADCP allows for large-scale deployment. This is essential in comprehending fully the complex coastal current patterns in the area around Fraserburgh. The greater the number of ADCPs deployed at different locations, the more we can comprehend the differences in currents across the region.

6. Choosing Proper Equipment for Measuring Current

Depending on Usage

• Shipborne ADCP: Ideal for collecting real-time current data along the course of a vessel near Fraserburgh. It can be used for oceanographic surveys, investigating the overall circulation in the area, and improving shipping routes, if accessible in the area.
• Bottom-mounted ADCP: Best for fixed - point monitoring of seabed currents in the long - term. This can be worth applying when researching long - term coastal current trends, including climate change impacts on the marine ecosystem of the region.
• Buoy-mounted ADCP: Ideally geared to measure surface - level currents over a large area as the buoy floats with the water. It helps towards the appreciation of the spatial variation of the surface currents and how the coastal waters are in contact with the open North Sea.

Based on Water Depth

• 600kHz ADCP: Ideal for water depths of up to approximately 70m, providing high-resolution measurements in the comparatively shallow waters off Fraserburgh.
• 300kHz ADCP: Ideal for water depths of approximately 110m, which can be useful for areas with slightly deeper spots in the North Sea off the town.
• 75kHz ADCP: Can be used for deep-water operations. While the waters off Fraserburgh are typically not deep, it can be used for study in relation to the deeper-layer currents or deeper channel regions, capable of measuring currents to 1000m depths.

There are several well-known brands of ADCPs in the global market, such as Teledyne RDI, Nortek, and Sontek. For those interested in a cheap one, the China Sonar PandaADCP, made of all-titanium alloy, offers great quality at an affordable price. You can learn more about it at (https://china-sonar.com/).

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