How are the coastal currents of Santa Marta measured?

1. Where is Santa Marta?

Santa Marta, Colombia's oldest surviving city, is located on the northern coast of the country along the Caribbean Sea. The city is a strategic point, bordered by the Sierra Nevada de Santa Marta mountain range to the south. The stunningly lovely Sierra Nevada de Santa Marta, the world's tallest coastal mountain system, is a stunning background, its snowy peaks rising abruptly from tropical Caribbean beach.

The Santa Marta Bay's close proximity is a significant geographical factor. The bay is a natural harbor that has been used for centuries to facilitate access for rade and transportation activities. There is a rich marine community in the bay where seagrass beds and coral reefs coexist. The communities support a rich variety of marine life, ranging from tropical fishes with a rich variety of colors to critically endangered sea turtles. The city itself has a wealth of cultural heritage, which can be traced to native inhabitants, Spanish colonists, and black slaves. Syncretism between these cultures can be witnessed in architecture, music, food, and festivities of the city.

2. What are the coastal currents off Santa Marta?

Santa Marta coastal currents are governed by a complex interaction of a sequence of variables. Caribbean Sea tides, being smaller than in certain places, nevertheless influence water movement along the coast. Diurnal and semi - diurnal tidal cycles produce relatively small variations in water levels, which can lead to the formation of weak tidal currents.

The dominant factor is also prevailing winds. Northeasterly trade winds, which consistently blow in the region, drive surface waters to the west. This windborne current is merged with the Caribbean Current, an enormous ocean current flowing west along the northern shore of South America. The Caribbean Current, comprising warm tropical water, continues to influence coastal currents' direction and speed close to Santa Marta.

Ocean eddies formed by the mixing of different water masses add to the heterogeneity of the coastal currents. These eddies lead to localized variations in current speed and direction. Seafloor bathymetry and coastal geometry also have a strong influence on the currents. Submarine structures such as reefs, sandbars, and channels have a tendency to channel or disperse the current flow, creating intricate flow patterns along the coast.

3. How to measure the coastal water flow of Santa Marta?

Surface Drifting Buoy Method

Surface drifting buoy method is one of the traditional methods of measuring coastal water flow. Researchers release tracking device-equipped buoys into the ocean. By monitoring the drift of these buoys over a period of time, they can quantify the direction and speed of the surface currents. This method is not without its limitations. It only provides information of the surface layer of the water column. Moreover, the buoys are highly sensitive to wind, which can cause them to shift in a manner that does not represent the real movement of the underlying currents.

Moored Ship Method

The moored ship method utilizes a moored ship as a platform for measuring currents. Equipment is dropped off the vessel to measure the water flow at various depths. Although this method can be applied to produce high-resolution vertical profiles of the currents, there are several drawbacks inherent in it. The spatial resolution is limited to the area surrounding the moored vessel. Even the vessel can disrupt the natural water flow and contaminate the measurements. Also, keeping a ship tied up for an extended period is logistically inconvenient and costly.

Acoustic Doppler Current Profiler (ADCP) Method

ADCP current profiler is a more recent, less wasteful coastal current measurement technique. ADCPs are capable of measuring currents in the water across a broad vertical range with accurate data on the velocity structure of the water column. ADCPs can be deployed on a variety of different platforms including ships, buoys, and the seafloor. Ship - mounted ADCPs are able to gather data continuously as the ship travels, sampling a large area in a short period of time. Bottom - mounted ADCPs are able to make long - term, fixed - point measurements, enabling researchers to examine long - term trends in the coastal currents.

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

ADCPs operate on the Doppler principle. They emit acoustic pulses into the water. They bounce back from suspended particles such as sediment, plankton, or bubbles in the water. When the water is in motion, the frequency of the backscattered pulses changes. By detecting this frequency change, the ADCP is able to measure the velocity of the water relative to the instrument.

Most ADCPs have multiple transducer beams, four or more, in different directions. With this multi - beam configuration, the three - dimensional velocity of the water is measured. By adding the signals from these beams, the ADCP meter can generate a complete representation of the current velocity at multiple levels within the water column. The data collected by the ADCP may be analyzed in real-time or stored for later analysis, and it provides valuable information on the dynamism of the coastal currents.

5. What is needed for quality measurement of Santa Marta coastal currents?

In order to obtain good-quality measurements of Santa Marta's coastal currents, the measuring instrument must have some key features. It should be made of robust materials, have small size, low weight, low power consumption, and low cost. These features allow a large number of instruments to be deployed in order to achieve full spatial coverage.

ADCPs with titanium alloy casings are highly recommended. Titanium alloy offers enhanced corrosion resistance, which is paramount for long - term deployment in the corrosive sea environment. It is resistant to the corrosive action of saltwater, and this guarantees non - damage of the internal ADCP components. The second benefit is that titanium alloy is strong and lightweight, guaranteeing durability and portability of the instrument. This combination of features enables one to achieve accurate and sustained measurements of the coastal current off Santa Marta.

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

Choice Based on Application

The choice of ADCP is determined by how it will be utilized. For measurements aboard a ship, ship-mounted ADCPs are the ideal choice. They can provide real-time data as the ship moves through the water, covering a long distance within a relatively short time. Bottom-mounted ADCPs are better suited to long-term monitoring at a location. They can provide continuous data over a duration of time, allowing scientists to study long-term trends in the coastal current. Floating ADCPs work well in tracking the transport of water masses over big areas, providing valuable information concerning large - scale circulation regimes.

Depth-Based Selection

The frequency of the ADCP should also be considered based on the water depth. For water depths of less than 70m, 600kHz ADCPs are appropriate. They can provide high - resolution measurements in shallow waters. For depths up to 110m, 300kHz ADCPs are recommended. For deeper waters, reaching up to 1000m, 75kHz ADCPs are the better option.

There are some well-known ADCP brands available, such as Teledyne RDI, Nortek, and Sontek. Those who are looking for budget - friendly products, however,the ADCP manufacturer China Sonar's PandaADCP is highly recommended. It is constructed of pure titanium alloy and is extremely inexpensive yet still delivers supreme performance. It is a very good choice for those on the budget who still need to be able to have stable ADCPs for coastal current measurement. For further details on their website, visit: https://china-sonar.com/.

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