Periodic Reporting for period 1 - WHIRLS (The impacts of ocean fine-scale whirls on climate and ecosystems)
Période du rapport: 2024-06-01 au 2025-11-30
WHIRLS explores whether fine-scale ocean processes can drive major changes in our planet’s climate and ecosystems. Heat and carbon — two key players in Earth’s climate — are constantly exchanged between the ocean and the atmosphere. This exchange is shaped by ocean processes such as eddies, or “whirls”, which move heat and carbon toward across the air-sea interface or redistribute within the ocean.
When the ocean releases heat and carbon to the atmosphere, the climate tends to become warmer and wetter; when it absorbs them, conditions cool. These same fine-scale processes also influence marine life — by changing nutrient flows, light availability, ocean layering, and the physical (re)distribution of organisms. Eddies and fronts help determine where and how ocean ecosystems thrive.
Despite their importance, the role of these small-scale ocean features is still poorly understood. WHIRLS takes an interdisciplinary approach to uncover how processes spanning 1–100 kilometres affect ocean circulation, air–sea exchange, biogeochemistry, and biodiversity.
WHIRLS’s research focuses on the Agulhas Current System around South Africa — one of the world’s most dynamic regions for ocean eddies, climate interaction, and marine productivity. Using research vessels, autonomous ocean platforms, and advanced high-resolution models, the researchers of the project will gather and analyse physical, chemical, and biological data across scales.
By combining cutting-edge observations, modelling, and data science, WHIRLS aims to deepen our understanding of fine-scale ocean dynamics and improve how they are represented in Earth System models. This will lead to more accurate predictions of future climate and its impacts on our oceans and planet.
When the ocean releases heat and carbon to the atmosphere, the climate tends to become warmer and wetter; when it absorbs them, conditions cool. These same fine-scale processes also influence marine life — by changing nutrient flows, light availability, ocean layering, and the physical (re)distribution of organisms. Eddies and fronts help determine where and how ocean ecosystems thrive.
Despite their importance, the role of these small-scale ocean features is still poorly understood. WHIRLS takes an interdisciplinary approach to uncover how processes spanning 1–100 kilometres affect ocean circulation, air–sea exchange, biogeochemistry, and biodiversity.
WHIRLS’s research focuses on the Agulhas Current System around South Africa — one of the world’s most dynamic regions for ocean eddies, climate interaction, and marine productivity. Using research vessels, autonomous ocean platforms, and advanced high-resolution models, the researchers of the project will gather and analyse physical, chemical, and biological data across scales.
By combining cutting-edge observations, modelling, and data science, WHIRLS aims to deepen our understanding of fine-scale ocean dynamics and improve how they are represented in Earth System models. This will lead to more accurate predictions of future climate and its impacts on our oceans and planet.
During the first 18 months of the WHIRLS project, the team has prepared the groundwork for its major field campaign.
Key and innovative oceanographic instruments—including a deep-reaching Moving Vessel Profiler (MVP300) equipped for the first time worldwide with multiple biogeochemical sensors; 16 biogeochemical Argo floats; three underwater gliders (one equipped with a nitrate sensor and another with a fine-scale turbulence package); a wave glider carrying a suite of oceanic and atmospheric sensors; Underwater Vision Profilers (UVP6) capable of reaching abyssal depths to be installed on biogeochemical floats; a nitrate sensor rated to 2000 m to be integrated into the CTD package of the South African vessel; surface tethered sediment traps; and the CTD rosettes of both the French and South African research vessels—have been procured, adapted, tested, and calibrated by the team members responsible for the observational and analytical components. These advanced platforms, together with additional equipment contributed by French, European, and South African teams, will enable high-resolution investigations of ocean-atmosphere interactions using both research vessels and autonomous systems. Several autonomous instruments have already been deployed around South Africa, both for testing purposes and to provide temporal extensions of the upcoming ship-based campaign.
A comprehensive scientific and logistical strategy for the large field campaign scheduled for the Southern Hemisphere winter (June–July 2026) has been jointly developed by the Principal Investigators, in close coordination with South African and European partners. This strategy integrates ship-based measurements, autonomous platforms, remote sensing, and modelling to capture the multi-scale dynamics of the Agulhas region.
The Marine Biogeochemistry Lab that will analyse most of the biogeochemical samples collected/generated during WHIRLS is now fully prepared to operate at the highest level to support the project. The isotope ratio mass spectrometer and peripherals are performing optimally, redundancies in both spare parts and technical expertise have been secured, and newly developed sample-processing methods have been implemented and validated.
The modelling team has developed a modern and extensive hierarchy of models to study submesoscale processes, but also to support planning of the observational campaigns, and to expand the observations in space and time. The central component is a km-scale (1/100°) nested model around South Africa for which a first 6-year long forced ocean simulation has been performed. It is currently the highest resolution that has been achieved to date. The coupling towards an active atmospheric model (then becoming a climate model) and a biogeochemical model is currently worked on, with production experiments expected in 2026.
The doctoral researchers in WHIRLS are each supervised by at least two Principal Investigators and all early career researchers (master students, doctoral researchers, and postdocs) gain valuable experience in interdisciplinary work through research visits with partner institutions. This close collaboration enables the early career researchers to contribute from the very beginning to the project’s integrated and synergistic approach to addressing its key scientific questions.
Key and innovative oceanographic instruments—including a deep-reaching Moving Vessel Profiler (MVP300) equipped for the first time worldwide with multiple biogeochemical sensors; 16 biogeochemical Argo floats; three underwater gliders (one equipped with a nitrate sensor and another with a fine-scale turbulence package); a wave glider carrying a suite of oceanic and atmospheric sensors; Underwater Vision Profilers (UVP6) capable of reaching abyssal depths to be installed on biogeochemical floats; a nitrate sensor rated to 2000 m to be integrated into the CTD package of the South African vessel; surface tethered sediment traps; and the CTD rosettes of both the French and South African research vessels—have been procured, adapted, tested, and calibrated by the team members responsible for the observational and analytical components. These advanced platforms, together with additional equipment contributed by French, European, and South African teams, will enable high-resolution investigations of ocean-atmosphere interactions using both research vessels and autonomous systems. Several autonomous instruments have already been deployed around South Africa, both for testing purposes and to provide temporal extensions of the upcoming ship-based campaign.
A comprehensive scientific and logistical strategy for the large field campaign scheduled for the Southern Hemisphere winter (June–July 2026) has been jointly developed by the Principal Investigators, in close coordination with South African and European partners. This strategy integrates ship-based measurements, autonomous platforms, remote sensing, and modelling to capture the multi-scale dynamics of the Agulhas region.
The Marine Biogeochemistry Lab that will analyse most of the biogeochemical samples collected/generated during WHIRLS is now fully prepared to operate at the highest level to support the project. The isotope ratio mass spectrometer and peripherals are performing optimally, redundancies in both spare parts and technical expertise have been secured, and newly developed sample-processing methods have been implemented and validated.
The modelling team has developed a modern and extensive hierarchy of models to study submesoscale processes, but also to support planning of the observational campaigns, and to expand the observations in space and time. The central component is a km-scale (1/100°) nested model around South Africa for which a first 6-year long forced ocean simulation has been performed. It is currently the highest resolution that has been achieved to date. The coupling towards an active atmospheric model (then becoming a climate model) and a biogeochemical model is currently worked on, with production experiments expected in 2026.
The doctoral researchers in WHIRLS are each supervised by at least two Principal Investigators and all early career researchers (master students, doctoral researchers, and postdocs) gain valuable experience in interdisciplinary work through research visits with partner institutions. This close collaboration enables the early career researchers to contribute from the very beginning to the project’s integrated and synergistic approach to addressing its key scientific questions.
To better understand the complex ocean system of the Cape Basin and the Agulhas Current system, WHIRLS will move beyond large-scale and regionally limited views. Using high-resolution models and coordinated field experiments, WHIRLS aims to capture a full 3D picture of how ocean processes change over time — from days to seasons, and longer timescales.
By combining detailed observations with advanced modelling, WHIRLS will study how model accuracy depends on resolution and test how well existing methods represent small-scale ocean motions. WHIRLS will also develop new ways to describe these fine-scale processes using artificial intelligence. Comparing heat and carbon exchange in high-resolution versus standard coarser models will allow to make recommendations for improving future climate models and international projects that inform major climate assessments, such as those of the IPCC report.
By combining detailed observations with advanced modelling, WHIRLS will study how model accuracy depends on resolution and test how well existing methods represent small-scale ocean motions. WHIRLS will also develop new ways to describe these fine-scale processes using artificial intelligence. Comparing heat and carbon exchange in high-resolution versus standard coarser models will allow to make recommendations for improving future climate models and international projects that inform major climate assessments, such as those of the IPCC report.