[Vendée Globe 2024 – #2] –In response to the Vendée Globe’s environmental commitments, some of the skippers have set about deploying their first scientific instruments. And judging by the videos taken on board, we can see both the skippers’ conviction to serve scientific research and the constraints and risks associated with these deployments in the open sea. What are these instruments? Where were they deployed? What protocols do the skippers have to follow? What will these measurements be used for? We tell you all about the first manoeuvres that marked this second week of the race.
As a scientific partner of the Vendée Globe, océans connectés provides scientific insights into the oceans during this 2024 race. Each week, we’ll be highlighting the particular ocean features crossed by the skippers and the highlights of some of their commitment to science.
by Carole Saout-Grit
Cover photo: The drifting buoy taken on board by skipper Manuel Cousin on his boat Coup de Pouce and deployed on 18 November 2024. (credit: Manuel Cousin)
An initial series of drifting surface buoys
This week, the ball started rolling for the deployment of scientific instruments. Five drifting surface buoys supplied by Météo-France were deployed by eight skippers during their route, at very precise latitudes between 24°N and 19°N. On receiving the buoys before the start of the Vendée Globe, each skipper was given precise instructions on the deployment protocol and the exact geographical position to aim for before launching. Arnaud Boissières (La Mie Câline), Boris Herrmann (Malizia – Seaexplorer) and Denis Van Weynbergh (D’Ieteren Group) began deploying the buoys, followed over the next few days by Louis Duc (Fives Group – Lantana Environnement) and Manuel Cousin (Coup de pouce).
Videos received from onboard confirm that these buoys are not easy to deploy. With an average weight of 20 kilograms and a spherical diameter of 400 millimetres, each buoy has to be carefully thrown overboard. Once in the water, it drifts away and is carried by sea currents.
Each drifting buoy is equipped with a GPS receiver, a sea surface temperature sensor, a barometric pressure sensor, a drogue presence sensor, a GPS positioning system and an Argos or Iridium satellite communication system for data transmission. A sock-shaped floating anchor is attached to the buoy by a long cable and stays behind it to allow it to drift.
Schematic diagram of a drifting surface buoy – Credit: NOAA
An international network since 1985
The measurements taken by these surface drifting buoys contribute to an international programme called DBCP (Data Buoy Cooperation Panel ).
An official joint body of the World Meteorological Organisation (WMO) and the Intergovernmental Oceanographic Commission (IOC ) since 1985, this programme increases the quantity, quality and timeliness of atmospheric and oceanographic data in ocean areas, in order to improve weather and ocean forecasts on a global scale and contribute to the study of climate and oceanographic research.
This DBCP programme actually covers two networks of two types of drifting buoys: drifting buoys (such as those deployed during the Vendée Globe) and fixed moored buoys, as well as the network of tropical moored buoys (such as the PIRATA network).
The objectives of the DBCP are to review and analyse buoy data requirements, coordinate and facilitate deployment programmes to meet network needs, and support information exchange and technology development. Scientists involved in this international programme also work to improve the quantity and quality of buoy data distributed on the Global Telecommunications System (GTS), initiate and support action groups, and liaise with relevant international or national bodies and programmes.
Status of the DBCP network worldwide on 30/10/2024. Each dot is an active buoy, and each colour distinguishes the contributions by country – credit: oceanOPS.
Since 1995, the scientific design of the global network of surface drifting buoys originally called for the maintenance of 1250 buoys around the world to calibrate satellite data on sea surface temperature. One buoy was needed, approximately every 500 kilometres across the world ocean, to calibrate and validate existing and new satellites.
High-frequency data from drifting buoys is transmitted in real time, free of charge, to the global scientific community. They are used to power operational services and are essential for improving global and regional weather forecasts and monitoring climate change. To date, it is estimated that around 1000 scientific publications have been published thanks to the scientific exploitation of drifting buoy data.
Multiple challenges for the future
Although the DBCP network of over 1,250 drifting buoys and 400 moored buoys was completed in 2005, challenges remain in maintaining and improving the network.
These include the need to upgrade the programme and encourage the addition of barometers on drifting buoys that do not have them. Measuring atmospheric pressure is important for weather forecasting and is done using a barometric port. As many buoys as possible should therefore be equipped with one, concentrating on high latitudes and remote ocean areas.
Another reality is that the buoy network is not uniformly dispersed over the entire ocean, because of the difficulties of deploying buoys in very remote areas (particularly in the Southern Ocean) and because the buoys, depending on the currents, drift rapidly away from certain areas or converge towards others. This represents a major challenge for the DBCP to identify new deployment possibilities to achieve the most uniform dispersion possible over all the world’s oceans.
Finally, the DBCP has set up an ongoing programme to develop and test new sensors and new uses for drifting buoys. Technological innovation and development phases to support the scientific objectives of better understanding the ocean and its role in the planet’s global climate.