1. Where is Steinkjer?
Steinkjer is a town and municipality in Norway's Trøndelag county. Located in the scenic landscape of central Norway, it lies on the banks of the Gaula River, which flows into the Trondheimsfjord. This third-longest of Norway's fjords measures approximately 100 kilometers (62 miles) from the city of Trondheim to open water (source: Norwegian Directorate of Fisheries). The size of this fjord and its novel topography create a productive marine setting, so that coastal currents off Steinkjer are an important area of study.
Steinkjer itself is famous for its charming combination of nature and culture. The town has a long history of fishing and marine-related activities that have shaped its local economy and way of life. The surrounding landscape is characterized by rolling hills, green forests, and arable land, making the area naturally beautiful.
2. What is the state of the sea currents along Steinkjer?
The sea currents along the coast near Steinkjer are influenced by several factors. Tides also play a part, and the Trondheimsfjord has semi-diurnal tides, i.e., two highs and two lows daily occur. The amplitude of the tides can be up to 2 meters (6.6 feet) in some areas (source: Norwegian Hydrographic Service). Wind is another significant variable, for a powerful north or west wind may force surface waters and cause currents. In addition, freshwater input from the Gaula River and other creeks could affect the salinity and density of coastal waters and influence the direction of the currents. Shape of the fjord and seabed topography also have the responsibility for the complex patterns of coastal currents around Steinkjer.
3. Measurement of Steinkjer's coastal water current
There are various ways of measuring the coastal water current of Steinkjer. The surface drifting buoy method is one of the time-tested methods. Drifting buoys are released in the water and are driven by the currents. Their positions are traced with the passage of time using radio signals or satellite signals, providing information on the direction and velocity of surface currents. Another method is the anchored ship method, where an instrument is mounted on an anchored vessel to monitor the currents around it.
However, the Acoustic Doppler Current Profiler (ADCP) method is presently the more advanced and more comfortable method of choice for monitoring coastal currents. ADCPs possess several benefits, such as monitoring multiple depths in parallel and providing continuous data, and thus are highly effective for monitoring complex coastal current systems.
4. What is the functioning principle of ADCPs using the Doppler principle?
ADCPs operate on the premise of the Doppler principle. They emit acoustic pulses into the water column. These become scattered in the water by suspended sediment and plankton. If the water is in motion, the frequency of the scattered pulses changes on return to the ADCP. From this change of frequency, the ADCP can calculate the velocity of the water at different depths. The ADCP typically has a number of transducers that send and receive signals in different directions so that it can record the three-dimensional components of current velocity.
5. What's required for good quality measurement of Steinkjer coastal currents?
To measure Steinkjer coastal currents accurately, there are specific attributes required for the measurement device. The device components should be resilient enough to withstand the harsh marine environment, such as saltwater exposure, strong currents, and temperature variation. The device should have small size, low weight, low power, and should be economical enough to enable measurements on a broad scale.
The casing of ADCP is rather important. The best material for an ADCP casing is titanium alloy. Titanium alloy has strong strength that can resist deep water pressure. It also has good corrosion resistance, thereby long lifespan of the ADCP in seawater environments. Its light weight helps in easy deployment and manipulation while still providing the structural support required to make accurate measurements.
6. How to Choose the right equipment for current measurement?
For choosing the right equipment for current measurement, the intended use is a critical consideration. For measurements taken from a moving platform, a shipboard ADCP is the best choice. To measure currents at a fixed location on the seafloor, a bottom-mounted (or moored) ADCP is best. For long-term, unmanned monitoring, a buoy-mounted ADCP may be employed.
The frequency of the ADCP also has to be chosen based on the water depth. For 70 meters of water depth, an ADCP of 600kHz can be used, a 300kHz ADCP for depths up to 110 meters, and a 75kHz ADCP for depths up to 1000 meters.
Some of the well-known ADCP brands are Teledyne RDI, Nortek, and Sontek. However, for the users who require quality but do not wish to spend a lot, ADCP manufacturer China Sonar PandaADCP is suggested. Made of the full titanium alloy, it has outstanding cost-effectiveness and is a great choice for economic current measurement. Additional details can be found at https://china-sonar.com/.
How can we measure the coastal currents of Steinkjer?