[Vendée Globe 2024 – #3] – As the frontrunners head at full prepare to round the first Cape of Good Hope, zoom on the BONUS-GOODHOPE project. This new and ambitious oceanographic project, which began in 2008, has linked Africa and Antarctica, revealing for the first time a hitherto little explored and little known Southern Ocean.
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 oceanographic vessel Marion Dufresne en route to the Southern Ocean during the BONUS-GOODHOPE 2008 campaign © Sabrina Speich
A major international project
2008, declared International Polar Year, saw the birth of an oceanographic project that was both unprecedented and ambitious. The BONUS-GOODHOPE programme brought together 27 international laboratories and institutes, supported in France by the CNRS, INSU, ANR, IPEV, Ifremer and IRD. The aim is to study in depth the complex interactions between ocean dynamics and biogeochemical cycles in the Southern Ocean. It should answer questions that are still unanswered about its mean state, its variability and its role in global ocean circulation and the state of the current climate in this vast, remote and hostile region of the ocean, which has so far been extremely poorly observed.
BONUS-GOODHOPE marks the establishment of the first long-term measurement network in the Southern Ocean, along a radial line linking the continents of Africa and Antarctica. The oceanographic campaign, conducted from 4 February to 24 March 2008 on board the oceanographic research vessel Marion Dufresne, enabled twenty-five researchers to explore this unknown zone for six weeks, stretching from Cape Town in South Africa to 57° 33′ south latitude in the Southern Ocean, along the Greenwich meridian.
BONUS-GOODHOPE campaign route (in red) linking Cape Town in South Africa to 57° 33′ S in the Southern Ocean, along the Greenwich meridian. BONUS-GoodHope IPY 2008
Thanks to an international and multidisciplinary collaboration between physicists, biogeochemists and modellers, BONUS-GOODHOPE represents a significant advance for oceanographic science, having opened up new perspectives on the global mechanisms governing the oceans and their role in the global climate system. The wealth of data collected makes this campaign a major first in the Southern Ocean, both in terms of the volume and diversity of the chemical, biological and physical parameters measured simultaneously. The integration of these data using numerical modelling tools is now providing an unprecedented vision of this complex environment.
In France, the programme was coordinated by Sabrina Speich, professor in the Geosciences Department at the École Normale Supérieure (ENS-PSL) and researcher at the Dynamic Meteorology Laboratory. Winner of the 2019 Albert Defant Medal, the climatologist has long been involved in United Nations committees coordinating climate and ocean observation. She is currently co-chairing the Ocean Observation Physics and Climate panel (OOPC ) under the aegis of the United Nations and the World Meteorological Organisation.
Sabrina Speich. © BONUS-GoodHope IPY 2008
Multi-disciplinary oceanographic campaigns for invaluable measurements
A campaign at sea is often a multidisciplinary project. Physicists, chemists and biologists embark on the same ship for what can be a long time (up to 2-3 months) to collect samples of water, chemical species and living organisms and take a series of measurements at sea along the way.
In some regions, currents can be violent and highly variable depending on the season. Physicists therefore need to take measurements of temperature, salinity and oxygen between the surface and the great depths, down to 6,000 metres. To quantify these currents, the measurements are taken day and night, and the teams work in three 8-hour shifts to ensure that the data is handled 24 hours a day.
Data is collected at sea using a dedicated device called a ‘bathysonde’, equipped with pressure, temperature, salinity and oxygen sensors and seawater sampling bottles mounted in a ring on a frame called a rosette. The whole assembly hangs from the end of a cable capable of conducting an electrical signal, which runs to the bottom with the bottles open. As the cable rises, the bottles are gradually closed at target depths.
Preparation for the descent of the bathysonde on board the vessel Pourquoi Pas? during the OVIDE 2018 campaign © Lherminier Pascale, Ifremer
Oceanographic vessels are also equipped with fully-fledged onboard laboratories, enabling the data collected to be displayed and used live. Some laboratories are also dedicated to chemical and biological analyses of the sea samples taken, as well as to their sometimes necessary conservation until their return to port.
Campaigns of opportunity to complement oceanographic research
To take the pulse of the ocean, oceanographic vessels are not the only ones collecting data at sea. Sailing boats, pleasure craft, commercial vessels, cruise ships, cargo ships and French Navy vessels can also collect samples or measure the physical or chemical parameters of the ocean. While oceanographic campaigns have a precise destination to address a well-defined scientific question, these ‘ships of opportunity’, whose primary vocation is not research, take advantage of their expeditions at sea to collect data as they go.
The skippers in the Vendée Globe are a fine illustration of this voluntary commitment to science. Some of them are deploying a wide variety of ocean instruments as they race: weather buoys last week, autonomous Argo floats, including two deployed this week for Yoann Richomme (Paprec Arkéa) and Sam Goodchild (Vulnérable).
These actions are highly complementary to the operations carried out by the oceanographers and are proving to be very useful for completing the measurement networks at sea, particularly in this remote and little explored Southern Ocean.
Targeted drop zone for the deployment of Argo floats during the Vendée Globe 2024. Located between 20° and 40° south latitude, before the Cape of Good Hope, this region, where the density of Argo floats is lower, is crucial for enriching our understanding of global ocean dynamics. Pelle Robbins / Woods Hole Oceanographic Institution Argo
Read the portrait of Sabrina Speich
Read the special issue on BONUS-GOODHOPE main results.
See Deployment at sea of Argo floats by skippers Yoann Richomme (Paprec Arkéa) and Sam Goodchild (Vulnérable) in the Vendée Globe on 26and 28 November 2024.