ADCP's Application to Ocean Current Measurement in Port of Los Angeles

1. Where is Port of Los Angeles?

The Port of Los Angeles is located in the San Pedro Bay area of Southern California. It is one of the largest and most important ports in the United States and a major global trade gateway.

Port Scale and Throughput

This port is large and has a huge area for terminals and a great number of berths. It has enormous throughput in handling a variety of cargo, and a huge percentage of its freight is containerized. It acts as a vital link in imports and exports and transports consumer products, electronics, automobiles, to name a few. The container traffic in the port is one of the busiest in the world, processing millions of TEUs annually.

Routes and Business

It is an important interconnection center between the United States and Asia. Various shipping lines are connected from the port to other major Asian harbors in China, South Korea, and Japan. The business operations involve a wide range of activities from importing raw materials to manufacturing and exporting finished goods. It also plays a vital role in the trade of agricultural products and high-tech equipment.

Port Management and Operation

The port is run by an efficient administrative and operational system. The management, while performing its other duties, oversees vessel traffic control, cargo handling, and security. All that puts vessels in berth with modern technologies and a skilled workforce to unload/load cargo. There are strict environmental and safety regulations so as not to harm the port and its surroundings.

Port Facilities

It is fully fitted with the latest facilities. The port has modern container terminals equipped with high-capacity cranes to manage containers quickly. In addition, it contains broad areas for storage in the form of container yards and warehouses for various kinds of cargo. Furthermore, the port provides ship repair and maintenance, bunkering, and logistic support services to make cargo movement easier.

Channel and Direct Shipping

The channels of this port are dredged deep enough for container ships and other vessels. It also provides direct shipping to most of the international ports. Its location on the Pacific coast gives it easy access to major shipping lanes, allowing convenient shipment of goods across the Pacific.

2. Why should we measure the ocean currents in the Port of Los Angeles?

The measurement of ocean currents has great significance in relation to the Port of Los Angeles. These are firstly connected with ensuring the safety of shipping. There is a number of aspects determining the maneuverability of vessels while in ocean water. By precisely calculating the pattern of currents, this will provide accurate guidance for vessels on their way in or out of the port. This helps in preventing accidents relating to collision against quay walls or other vessels, in case of strong or variable currents.

It is also good for the optimization of port operation. The knowledge of the present velocities will help the ships to adjust their speeds and routes, hence less fuel consumption. For example, favorable currents can be utilized by ships to enter or leave the port in less time, thus enhancing the overall productivity of the port and reducing vessel waiting times.

Besides, for the long-term maintenance of the port infrastructure, sediment deposition around the port can be influenced by ocean currents. In this respect, the monitoring of the currents allows the port management to better plan dredging activities and take measures to protect the integrity of the port channels and berths. Compared to traditional techniques, ADCP current meter is more advanced and convenient in the measurement of current.

3. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of Doppler. They transmit acoustic signals into the water. The interaction of these acoustic waves with moving particles in the water-for example, suspended sediments or even small organisms-alter the frequency of the reflected waves due to the Doppler effect.

Ship-borne ADCP

In the Port of Los Angeles, a ship-borne ADCP can be installed on various vessels such as survey ships or port-service vessels. While the ship is underway, the ADCP current profiler sends acoustic pulses downward and sideways. The frequency shifts of the reflected pulses from different depths are measured. These Doppler shifts are interpreted to compute the current's velocity with depth. The data obtained may be utilized either in real-time navigation or it may be stored for post-processing.

Fixed ADCP

Fixed ADCPs may be installed on the seabed, on the side of piers, or other fixed structures. The fixed ADCPs are those that constantly transmit and receive acoustic signals. These are the devices which have a long record of current velocities and directions for the site, while useful to determine local patterns in current variations over longer terms.

4. What’s needed for high-quality measurement of Port of Los Angeles currents?

It should be of specific characteristics for the measurement of quality current in the Port of Los Angeles. Materials of the equipment must be dependable. For example, it is desirable that the casing of the ADCP flow meter should be of titanium alloy. The corrosion resistance of a titanium alloy is superb, which is highly essential in sea water. It can resist the corrosive action of salt water and keep the equipment durable for a long period in that condition.

The size of the equipment should be small and the weight light. A small and lightweight ADCP profiler is easier to install either on a ship or at a fixed location. It reduces the load and space that it will occupy, making it more convenient for usage.

The other important factor is low power consumption. Since the equipment should work continuously in the port environment, equipment with low power consumption can work for longer without frequent battery replacements or excessive energy supply. In addition, the cost of the equipment should be reasonable to allow for large-scale deployment for comprehensive current measurement.

5. How to Choose the right equipment for current measurement?

Selection of the correct equipment in relation to measuring the current within the Port of Los Angeles varies for certain applications.

Type of Installation

• Ship-borne ADCP: Whenever measuring the current with vessel movement is aimed at or intended to do various surveys throughout specific areas in this port, this type should suffice.
• Bottom-mounted ADCP: For long - term and fixed - point monitoring of current conditions, especially near critical port structures such as channels and berths, bottom - mounted ADCP is the better option.
• Buoy-mounted ADCP: When the focus is on the surface and upper - layer current patterns in the open water area of the port, buoy-mounted ADCP can be considered.

Based on Frequency

The choice of frequency depends on the depth of the water: an ADCP of 600 kHz can measure to about 70m water depth, hence reaching even more shallow areas of the port, while an ADCP of 300 kHz would be more appropriate for up to about 110m and would be more representative over the main port areas. A 75 kHz ADCP is designed for much deeper waters, up to 1000m, and can be used in areas with significant water depth such as near the port entrance.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also worth noting. It is made of all - titanium alloy material and offers an excellent cost-performance ratio. You can find more information on its website: (https://china-sonar.com/).

Here is a table with some well known Acoustic Doppler Current Profiler(ADCP)  instrument brands and models.