Research on a shoestring

To measure waves, ocean currents, salinity or temperature in the ocean, scientists use various instruments that drift in the sea or are anchored to the ocean floor.

A CTD (Conductivity Temperature Depth) probe can, for example, be placed in buoys that float freely around the ocean and measure temperature and salinity. So-called gliders, looking like torpedoes, are programmed to travel along specific routes in the sea.

All these instruments collect important information about the ocean, which in turn is used to verify forecast models or satellite observations. This is helping meteorologists making more reliable weather and sea forecasts.

A measuring instrument on a shoestring

Traditional instruments are quite expensive and have to be launched from research vessels. But, with the right skills, it is possible to build one yourself for relatively small costs.

Researchers at the Norwegian Meteorological Institute (MET Norway) have recently managed to build affordable instruments that measure the state of the sea. They work so well that several projects have already been initiated to bring this concept further.

A cheap box

MET Norway is now collaborating with the University of Bergen on the development of so-called drifters.

- It is incredible how far the electronics have come, says researcher Jean Rabault who for several years has built his own instruments. One is measuring waves in the sea ice north of Svalbard, a part of the project The Nansen Legacy.

The components fitting inside the small box in the picture above includes a powerful micro controller, GPS, satellite modem and a sensor that has a built-in accurate accelerometer, gyroscope, and compass.

All together it costs less than 700 Euro.

- Just add a couple of batteries and find a suitable waterproof box and we are ready to conquer the world's oceans, and send messages from anywhere in the world, he says.

Will revolutionize ocean observations

During the ongoing One Ocean Expedition, drifters were launched by researcher Lars R. Hole and students from the University of Bergen.

On November 10, 2021, the expedition was located just north of Curaçao in the Caribbean Sea. The home-made drifter was named "Floatenstein" before the release, due to its somewhat rough appearance.

- Jean Rabault built Floatenstein at a fairly short notice before the voyage, but it has worked beyond all expectations. The cost of only 700 Euro is a very low sum for a scientific instrument, says Hole.

What happens to Floatenstein?

After two months at sea in up to three meters of waves and several hundred kilometers of operation, Floatenstein is near Belize in January 2022.

- It is exciting to see if it hits land, or if it continues its life out at sea, says Hole.

If it hits land now, the researchers will contact colleagues in Belize and hope that they can pick it up in exchange for using the data it has collected.

This is in line with the MET Norway's open data policy and strong sharing culture.

What is measured?

Floatenstein measures sea temperature and waves, and also logs it's track, the so-called trajectory. This helps to verify the trajectory model called OpenDrift that MET Norway has developed.

Not only researchers study the data from Floatenstein. Master's student Judith Ølberg at the University of Bergen will work with the wave measurements it sends home.

What are the measurements used for?

Floatenstein helps to double-check whether the models and measurements that the researchers already have are good.

Researcher Patrik Bohlinger at MET Norway has created the software Wavy, which retrieves satellite data from a specific area. This way, researchers can check whether their small craft reports the same information as measurements done by satellites.

In the diagram below, a comparison between Floatenstein's measurements and satellite observations is plotted.

In the wake of Floatenstein

MET Norway is planning to build more of these floaters, and also in collaboration with Slåtthaug upper secondary school in Bergen. The students get useful practice and the researchers get to build more floaters.

- Hopefully the students gain insight into the usefulness of research and good observations. We think it is motivating for them to contribute to real projects, says one of the other researchers, Gaute Hope.

Hope builds floaters that use GSM communication. He makes these for less than 200 Euro. These floaters can be used along the coast, as far out as there is mobile coverage.

The researchers at MET Norway and the Institute of Marine Research are planning a larger field trial the summer of 2022. The goal is to simulate how salmon louse is drifting in the sea in a more accurate way than before.

And what happens to the drifters in the ocean? Since the position is known, they will eventually be retrieved.

The article is produced by the Norwegian Meteorological Institute (MI), and was first published on forskning.no - where MET Norway is one of the owners. Translated by Ronald Toppe, One Ocean Expedition.