Operational Systems and Coastal Ocean Dynamics

Measurements in COSYNA are carried out with the assistance of many different systems, such as gliders, buoys, FerryBoxes, satellites and radars. -image: HZG-

COSYNA (Coastal Observing system for Northern and Arctic Seas) is a broad system, enabling the systematic and continuous observation of the northern and Arctic coastal waters. Computer models, which simulate coastal sea processes, can be examined and improved using the data collected. The objectives are to describe the current environmental condition and to make short-term forecasts.

The processed data can be utilised by government bodies, the commercial sector and by the public to better plan routine tasks. The data can also assist in exceptional situations so that contaminants, oil spills or poisonous algae blooms can be properly handled. An additional area of application lies in long-term estimates and forecasts.

COSYNA also develops and improves scientific products such as North Sea current maps. Furthermore, measurement buoys and other scientific instruments are utilised, developed and optimised.

In cooperation with many partners, COSYNA expands knowledge of the coasts in “our backyard” and globally—as well as on their regional coastal characteristics.

More information on COSYNA homepage.

For observing processes in small geographical regions at sea, a multitude of measurement instruments are utilised from the air and in the water. -image: HZG-

For observing processes in small geographical regions at sea, a multitude of measurement instruments are utilised from the air and in the water. -Image: HZG-
Ocean waters move in the most varied ways. One process that can be observed involves eddies, which usually develop when waters of different temperatures come into contact with one another. Fronts also develop. Waters of different temperatures and salinity are discernably separated from each other.
The term "submesoscale structures” indicates eddies and fronts with sizes ranging between one hundred metres to ten kilometres.

It is believed they play an important role in the global energy budget. They also strongly interact with biogeochemical and biological processes in, for example, phytoplankton production.
New theoretical coastal models can now also take into consideration the properties of these eddies and fronts, and therefore intensified scientific attention is now given to these submesoscale structures.

There are, however, few actual observations. Submesoscale eddies and fronts are difficult to find and track using traditional research ships and satellites. These eddies often only exist for a number of hours. They must also be determined with a precision of a few metres, something that requires a great deal of effort due to the adverse conditions on the open sea.

The University of California, Los Angeles (UCLA) has begun an array of submesoscale observations of these eddies and fronts ("SubEx – Submesoscale Experiments"), which have now been continued by the Helmholtz-Zentrum Geesthacht. Close cooperation exists between UCLA, NASA’s Jet Propulsion Laboratory (NASA/JPL), the University of California, Santa Barbara (UCSB), the Naval Research Laboratory (NRL) and universities in Victoria, Oldenburg and Twente.

In the "hunt" for eddies, aircraft are fitted with several high-sensitivity infrared cameras, hyperspectral cameras and extremely precise observation radars. These instruments supply information on the temperatures of the sea surface, ocean colour, and the surface roughness. Scientists can thereby determine the positions of eddies and fronts from airplanes. Several fast boats can then bring measurement instruments to the eddies. These instruments, directly on site, measure the temperatures in deeper water layers, salinity and oxygen content of the water, the current velocity and direction at various depths and other crucial parameters. The circling airplanes coordinate these measurements on site because the eddies continue to move and the boats must travel through the eddies several times to capture the greatest amount of data possible.


Further information on submesoscale processes can be found here.

A researcher calibrating a FerryBox. -Bild: HZG-

The interactions between physical, chemical and biological processes are referred to as “biogeochemical material cycles”. These interactions are particularly complex in the shallow coastal waters because a close connection exists between processes on the seafloor and the water above it.

Researchers at the Helmholtz-Zentrum Geesthacht study oxygen, carbon and nutrient content in the North Sea. Using research ships, FerryBoxes, gliders and stationary platforms directly on site, many measurements of these biogeochemical variables can be carried out. The data is supplemented by ocean colour satellite measurements.

Computer models then help in processing and evaluating the obtained data. Scientists can use both the models and the data to describe the complex balance of these coastal sea biogeochemical interactions.

Scientists can, for example, create forecasts to predict algal blooms using the obtained insights.

Wind farms in the North Sea present new challenges for engineers and scientists. -image: V. Schlichting (istock)-

Wind turbines erected in large groups near the coast are called “offshore wind farms”. They are currently under substantial expansion in efforts to convert to renewable energy.

Because they possibly have considerable influence on the marine environment, they are a focus of scientific investigations. The COSYNA system is utilised in these studies with its comprehensive observation capabilities, including radar, buoys and satellites.

Such observations include sea state and waves in the vicinity of these wind farms. The data are fed into the COSYNA computer models. The information obtained is made available to the public and to interested parties.
Observation and analysis methods, particularly concerning changes in the marine environment due to offshore wind farms (e.g., currents, water turbidity, and biological production) are also developed further and adapted.

Coasts around the world not only look different but also possess different properties. -image: HZG-

Coastal waters, a region of the ocean, contribute to global processes in many ways.
The “global coast”—the importance of the coastal oceans for large-scale processes—is a focus of study in the New Technologies Department. Among the topics of interest are the carbon exchange between the coastal seas and the open ocean as part of the global carbon cycle and the ocean's energy budget as one of the important influences on worldwide climate.

For investigating these questions and similar issues, the New Technologies Department develops and builds mobile measurement stations, which can be utilised in research projects all over the world. The data obtained is analysed and fed into computer models. This serves not only to examine and improve the models, but the data can also be used to describe and understand central processes and mechanisms in the coastal seas.

The measurement systems, like the computer models, are designed to be as flexible as possible. This enables scientists to quickly adjust to new research questions and regions.

The objective is to describe coastal sea processes for specific regions as well as for the "global coasts".