1. Where is Namsos?
Namsos is a picturesque municipality in the Trøndelag county of Norway. It occupies a picturesque location along the central Norwegian coastline, where it sits strategically at the river mouth of the Namsen, which courses through emerald valleys and then flows into the broad Namsfjord. The fjord, stretching about 60 kilometers (37 miles) inland into the mainland, is located in this area and serves as a crucial body of water that not only offers a natural harbor but also impacts the environment and maritime culture of Namsos.
Namsos town itself is a charming blend of older Norwegian and newer facilities. With its timber buildings along the quayside, bustling fishing harbour, and active native population, Namsos is inescapably coastal in nature. Fishing and fish processing industries have been the economy around here for centuries and have established a rich maritime heritage. Beyond the municipality, the ground is a glorious landscape of rocky mountains, dense forest, and steep cliffs falling to the sea, offering a picture-book environment for the ocean waters.
2. What is the state of the coastal currents near Namsos?
Coastal currents near Namsos are defined by a variety of factors. Tides are especially significant, for the area experiences semi-diurnal tides with a tidal range increasing as much as 2.2 meters (7.2 feet) in some locations (source: Norwegian Hydrographic Service). These tides control ebb and flow of water in and out of the Namsfjord, creating strong and changing currents, especially near the fjord entrance and river estuary.
Another important feature is wind. The strong and frequently turbulent northern and western winds can churn the surface waters and generate strong currents that affect fishing and navigation. The Namsen River and some of the minor streams also contribute to the coastal currents by adding freshwater into the sea. The addition of freshwater alters the salinity and density of the seawater, which in turn affects the buoyancy and movement of water masses. In addition, the complex underwater relief of the fjord, i.e., underwater ridges, channels, and shoals, all influence the currents' patterns further so that coastal currents off Namsos are dynamic and unpredictable.
3. Observation of the coastal water flow of Namsos.
There are several ways to observe the coastal water flow of Namsos. The surface drifting buoy method is one of the traditional methods. Free-drifting floats, equipped with GPS tracking devices, are released into the water and swept away by the currents. By monitoring the time evolution of the movement of the floats, researchers can obtain information concerning the direction and speed of the current at the surface level. This is a partial solution since it is merely providing information for the surface layers of the water column and is not representative of the current at the lower levels.
The ship-anchored technique is a technique where a boat is anchored at a location and equipment is placed on the boat to record the currents surrounding the location. As great as this technique can yield detailed measurements in an area, it has poor spatial extent and continuous monitoring of large-scale current patterns.
On the other hand, the Acoustic Doppler Current Profiler (ADCP) method has been found to be a more advanced and effective way of quantifying coastal currents. ADCPs can quantify currents at various depths and thus provide a comprehensive three - dimensional description of the motion of the water. ADCPs can work continuously, collecting information over extended periods of time, and as such, they are highly efficient in studying the intricate and continually changing coastal current system surrounding Namsos.
4. What is the operation of the Doppler principle-based ADCP?
ADCPs operate on the Doppler principle. They transmit acoustic signals into the water column. The suspended particles in the water, for example, sediment, plankton, and organisms, backscatter the acoustic signals. Since the water is in motion, the particles also follow the water and cause the frequency of the backscattered acoustic signals to change as they return to the ADCP.
With this accurately measured change in frequency, or Doppler shift, the ADCP calculates the water velocity at different levels. Most ADCPs are made up of a number of transducers that transmit and receive signals in different directions. By so doing, it's capable of measuring the three-dimensional aspects of the current velocity, whereas it provides specific information regarding the magnitude and direction of the current flow at different levels within the water column.
5. What are the requirements to achieve high - quality measurement of Namsos coastal currents?
In order to achieve high - quality measurement of Namsos coastal currents, the equipment used for measurement should possess some inherent necessary qualities. The equipment must be fabricated with extremely dependable materials capable of functioning satisfactorily within the harsh marine environment characterized by saltwater exposure, high currents, and changing temperatures.
The equipment must be small in size, lightweight, and have low power consumption. They must be mass deployable, whether in ships, buoys, or seafloor - mounted. Smaller and lighter design facilitates handling and deployment, whilst minimum power requirements provide longer running times, especially for automatic monitoring systems. Cost - effectiveness is also a critical consideration, since this facilitates wider application of the technology to many research and monitoring applications.
The enclosure of an ADCP is particularly important. Titanium alloy is the ideal material for the enclosure of an ADCP. It has high strength, and the instrument can therefore withstand the high hydrostatic pressure of the saltwater at lower levels of water. Its high corrosion resistance ensures that the ADCP will remain functional and provide precise readings even in the extremely corrosive saltwater environment. In addition, the light nature of titanium alloy also simplifies deployment and recovery without sacrificing the structural integrity necessary for precise and reliable measurement.
6. How to Select the appropriate equipment for current measurement?
Selecting the appropriate device for Namsos current measurement will depend on the application. For measurements at sea on a traveling ship, a shipboard ADCP is most appropriate. This is due to the fact that such an ADCP is mounted especially on ships and is capable of measuring currents continuously as the ship travels along the water.
If the goal is to measure currents at a seabed point, a bottom-mounted (or moored) ADCP is preferable. These ADCPs are anchored and mounted on the seabed and continuously monitor the local current conditions for long periods of time.
For independent and flexible monitoring of expansive areas, a buoy-mounted ADCP is a suitable choice. These ADCPs are installed on floating buoys, which can be deployed in strategic points for data gathering for current trends.
Also of prime concern is the frequency of the ADCP, which needs to be selected as a function of the water depth. A 600kHz ADCP works best for water depths below 70 meters, a 300kHz ADCP for up to 110 meters, and a 75kHz ADCP for up to 1000 meters.
Among the popular ADCP brands are Teledyne RDI, Nortek, and Sontek. Nevertheless, for those looking for high - quality but affordable options, the ADCP manufacturer China Sonar PandaADCP is strongly suggested. Made of full titanium alloy, it is incredibly cost - effective, rendering it a great alternative to economic current measurement. For more information about this incredible product, check out https://china-sonar.com/.
How do we measure Namsos' coastal currents?