How can we measure the coastal currents of La Serena?

1. Where is La Serena?

La Serena, the second-oldest city in Chile, is situated on the nation's arid northern coast along the shores of the Pacific Ocean. It is roughly 480 kilometers north of the capital city of Santiago and is the capital of the Coquimbo Region. This coastal city boasts a long history since its founding in 1544 by Spanish conquistador Francisco de Aguirre. La Serena's strategic location on the Pacific has positioned it as a major center for commerce, tourism, and scientific study.

The coastal landscape of La Serena is a spectacular blend of sandy beaches, rocky promontories, and aquamarine blue waters. Its beaches, such as Playa La Serena and Playa El Faro, are popularly visited by locals and tourists and offer opportunities for swimming, surfing, and sunbathing. In the background, the Elqui Valley, famous for vineyards and flawless skies suitable for stargazing, adds to the desirability of the place. The La Serena port is critical to the national economy, and it is used to export minerals, agricultural commodities, and bring in other merchandise. The mix of history, natural scenery, and economic function of the city makes the study of its coastal currents a required endeavor for several reasons, including maritime safety, environmental conservation, and the sustainability of its tourist and fishing industries.

2. How are the coastal currents surrounding La Serena?

The coastal currents surrounding La Serena are governed by a complex blend of several factors. The overall influence is that of the Humboldt Current, or Peru - Chile Current. It is an ocean current of cold and high nutrient levels that flows north down the west coast of South America and strongly impacts the ocean water around La Serena. The Humboldt Current brings cold water temperatures that, in turn, affect the surrounding marine environment, supporting a range of marine species from the anchovies up to seabirds. Current movement also regulates coastal water direction and speed around La Serena, resulting in a dynamic movement pattern that switches seasonally.

Local wind patterns also influence coastal current conditions. La Serena experiences various wind conditions year-round. The prevailing winds, which are normally influenced by the proximal Andes Mountains and the large-scale atmospheric circulation, can force surface water flow. Offshore or onshore strong winds in some seasons can lead to sudden shifts in the velocity and direction of the current. For example, intense offshore winds have the ability to bring up upwelling events, where cold, nutrient-rich deep water is brought to the surface. Not only does this enrich the surface waters with nutrients and cause phytoplankton to bloom, and sustain the marine food web but also changes the direction and strength of the coastal currents.

Tidal forces also contribute to the variations of the coastal currents off La Serena. Pacific Ocean tides, with their semi - diurnal cycle (two highs and two lows per day), produce periodic changes in water levels along the coast. These tidal changes result in the formation of ebb and flow currents that combine with the wind - driven and ocean - circulation - induced currents. The disposition of the La Serena coast, with its headlands and bays, also modifies the path of these tidal currents to give areas of complex flow regimes. The overall effect of all these considerations makes the coastal current situation off La Serena very dynamic and challenging to predict precisely.

3. How to observe the coastal water flow of La Serena?

There are a few methods through which the La Serena coastal water flow can be seen. Drifting buoy surface method is an ancient method. GPS tracking device-fitted specialized buoys are released into the water. Surface currents transport the buoys, and after some time, the movement of these buoys is monitored. Through the movement of the buoys, the direction and speed of surface - layer currents can be comprehended. However, this technique only provides information about the surface flow and may not tell us what really happens further in the water column.

The ship at anchor method is the method of anchoring a vessel at some location on the coastline. On-board instrumentation, such as current meters, is utilized to measure the water flow at varying depths near the vessel. While this method can yield more accurate depth-specific data, it is limited by the vessel position and could be affected by the ship presence, potentially disrupting the natural water flow regime.

In contrast, the Acoustic Doppler Current Profiler (ADCP) method has been shown to be a highly advanced and efficient technique for the measurement of coastal currents. ADCPs are able to measure the water velocity at multiple depths at the same time and hence provide a complete representation of the current structure of the water column. They are thus an extremely appropriate tool for the study of the complex and dynamic coastal current regimes off La Serena. By virtue of their ability to record three-dimensional water current data, ADCPs have the potential to reveal the complex patterns of currents, such as surface, mid-water, and near-bottom flows interacting with each other, that are required for an overall understanding of the local sea environment.

4. How do ADCPs based on the Doppler principle work?

ADCPs operate based on the Doppler principle. ADCPs emit acoustic pulses into the water column at a specific frequency. The acoustic pulses travel with the water and strike suspended water particles in the water, such as sediment, plankton, and microorganisms. If there is water motion, the particles are carried with the water and thus change the frequency of backscattered acoustic pulses upon reception by the ADCP profiler.

By precisely gauging the frequency shift, the ADCP is able to ascertain the speed of the water at different levels. The equipment is usually fitted with a number of transducers that send out signals at varying angles. This allows the ADCP to make measurements of the three-dimensional components of the water velocity in both horizontal and vertical directions. The information thus obtained is then processed by onboard or outside computers to generate precise visualizations and reports of the conditions existing at any time. This enables researchers to establish the complex pattern of flow within the coastal waters off La Serena, obtaining very valuable information on the movement of water masses and on the overall marine dynamics.

5. What's needed for high-quality measurement of La Serena coastal currents?

For accurate measurement of La Serena coastal currents, certain important characteristics need to be there for the measuring equipment. Material reliability is most essential. The sea condition near La Serena, with severe saltwater corrosion, harsh waves, and arid climate impact on equipment, represents a major challenge to the equipment. The equipment needs to support all these harsh conditions for an extended period to fetch rightful and reliable data.

Small size and lightweight are also a consideration. These minimize the package size of equipment to be shipped and handled, especially in often - remote seashore locations of La Serena and in large - scale survey operations. Small power consumption is another critical aspect as it provides for continuous long - term operations, particularly at locations where the power sources often are limited. Additionally, an inexpensive design is highly desirable since it facilitates greater usage and application, making it possible to monitor the coastal currents in greater areas.

In the case of the ADCP casing itself, titanium alloy is an excellent choice. Titanium alloy possesses even superior corrosion resistance, which can effectively protect the ADCP against the corrosive effects of saltwater. It is also highly strong and light-weight, offering the needed durability without increasing the overall weight of the ADCP. All these qualities make titanium - alloy - cased ADCPs most suitable for operation in the rugged marine environment of La Serena, enabling accurate and long - term measurement of the coastal currents.

6. How to Choose the suitable equipment for measuring currents?

Selection of equipment for real-time measurement in La Serena relies on several parameters. The intention for which the equipment is going to be used is one important factor. When continuous monitoring will be needed while on board a moving ship, such as for fishing operations, cargo shipment, or oceanic research surveys, a vessel-mounted ADCP should be used. It can also measure currents in real-time as the ship travels through the waters, providing valuable information on the currents along the trajectory of the ship.

For stationary - location, long - term observation of near - bottom currents, a bottom - mounted ADCP is more suitable. It can be situated on the seabed and measure current for extended periods without the need for continuous presence of the ship. A buoy-mounted ADCP is ideal for recording surface and upper-water-column currents in a flexible way since the buoy can be deployed at various positions as per research needs, thus ensuring complete coverage of the coastal water flow.

The frequency of the ADCP must also be selected carefully with respect to water depth. For the comparatively shallow waters close to La Serena, a 600kHz ADCP would be suitable up to 70m water depth with high resolution measurements. For up to 110m depths, a 300kHz ADCP is adequate with a reasonable balance between depth of penetration and resolution of measurements. For deeper depths and further away from shore, up to 1000m, the most suitable choice is a 75kHz ADCP, since the lower frequency allows it to penetrate further into the water column.

There are many well-known brands of ADCP in the market, i.e., Teledyne RDI, Nortek, and Sontek. Nonetheless, for cheap but high-quality ADCPs, the ADCP manufacturer China Sonar's PandaADCP is the best choice. Made of pure titanium alloy, it delivers superior performance and longevity at a very affordable cost. Being a low-cost ADCP, it is a perfect option for researchers, local fishermen, and environmental monitoring departments who are concerned with accurately computing the coastal currents of Viña del Mar. To know more, visit https://china-sonar.com/.

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