GEOMAR's WHIRLS Campaign Deploys Autonomous Fleet off South Africa

An international research campaign led by Germany's GEOMAR is deploying two research vessels and a large fleet of autonomous systems off South Africa to study how small-scale ocean movements shape climate and marine life. Running from 20 June to 29 July 2026 in the energy-rich Agulhas Current region, the WHIRLS campaign simultaneously observes the ocean and lower atmosphere across around 40,000 square kilometres. The flagship experiment of a European Research Council Synergy Project, it aims to reveal how eddies, fronts and filaments spanning just a few kilometres influence large-scale climate dynamics and biodiversity.

 

The Scientific Question at the Centre

 

The campaign addresses how small-scale ocean movements influence climate and marine life. Researchers from GEOMAR are investigating this question alongside international partners off the coast of South Africa. The aim is to better understand the interactions between the ocean, the atmosphere and marine life. Central to this is demonstrating how small-scale processes shape the large-scale dynamics of the climate system. This focus places the campaign at the intersection of physical, chemical and biological ocean science.

The research targets the ocean's role as a central component of the Earth system. The ocean absorbs most of the excess heat generated by human activities and a significant share of emitted carbon dioxide. It also sustains ecosystems essential for food security, the economy and biodiversity. Many of these processes are strongly influenced by small-scale oceanic movements. Understanding these movements is therefore key to understanding the ocean's wider climatic role.

 

Why Small-Scale Structures Matter

 

The structures under study are small but disproportionately influential. Eddies, fronts and filaments span just a few kilometres and develop over days to weeks. Despite their modest size, they play an outsized role in ocean processes. They control the exchange of heat and carbon dioxide with the atmosphere. They also govern the vertical transport of nutrients from the depths and the organisation of marine life.

These structures have long been difficult to study and document. Their transient nature makes them challenging to observe with conventional methods. As a result, they remain inadequately documented in the scientific record. Their effects are not yet sufficiently accounted for in climate models. The WHIRLS project examines the ocean, atmosphere and ecosystems precisely at the scales where their interactions are most intense.

 

A Natural Laboratory in the Agulhas Current

 

The campaign focuses on the Agulhas Current, one of the most energy-rich ocean currents on Earth. In this region, warm waters from the Indian Ocean meet colder waters from the Atlantic and Southern Ocean. This convergence produces intense turbulence, steep temperature gradients and vigorous exchange with the atmosphere. Some of this warm water flows into the Atlantic, feeding the great ocean circulation that distributes heat across the planet. This makes the region a significant node in the global climate system.

The timing of the campaign enhances its scientific value. It runs during the southern winter, when contrasts between the ocean and atmosphere become more pronounced. Storms occur frequently during this period, and small-scale processes are particularly active. These conditions make the region an ideal natural laboratory for the research. The seasonal intensity allows scientists to observe the processes at their most dynamic.

 

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The Multi-Platform Observation Network

 

The campaign centres on two research vessels acting as mobile observatories. The MARION DUFRESNE from France and the SA AGULHAS II from South Africa work in close collaboration. Together they carry out measurements almost simultaneously across around 40,000 square kilometres. Their work investigates the three-dimensional structure of the upper 1,000 metres of ocean and the lower atmosphere. This coordinated approach allows a broad area to be studied at once.

Because the ships cannot be everywhere, they are supported by an extensive autonomous fleet. This includes underwater gliders, wave gliders, sailing buoys and around 200 surface drifters. It also features 18 profiling Argo floats and Saildrone-type marine drones. Around 300 atmospheric soundings are conducted using radiosonde balloons and profilers, supplemented by laser-based wind measurements and aerial drones. Together this network provides unprecedented spatial and temporal resolution, tracking ocean structures almost in real time.

 

Observing Life From Viruses to Mammals

 

The campaign's biological programme is notably comprehensive. Water samples are analysed for nutrients and their isotopic composition. Plankton nets capture larger organisms, while genetic and genomic analyses record biodiversity down to viruses and bacteria. On a larger scale, acoustic systems detect zooplankton and fish. Observers also count seabirds and marine mammals across the study area.

This breadth allows researchers to connect physical processes to biological outcomes. Small-scale oceanic structures often create zones of high biological concentration that attract predators. Tracking these dynamics from viruses to mammals alongside physical and chemical processes offers an integrated view. This combined perspective on the marine biome is rarely achieved in ocean research. It links the smallest organisms to the largest predators within a single framework.

 

International Collaboration and Broader Goals

 

The campaign forms the centrepiece of a major European research project. WHIRLS is funded by the European Research Council under the Horizon Europe programme. It brings together physical oceanographers, modelling specialists and biogeochemists from Germany, France, Sweden and South Africa. The project is led by four principal investigators based at institutions across these countries. Advanced ocean and climate models complement the observations, placing the data in a broader context.

The collaboration extends well beyond the core consortium. WHIRLS involves partners from South Africa, Germany, Sweden, France, Italy, the United Kingdom, China and the United States. Numerous research institutes and space agencies also contribute to the effort. By observing physics, biogeochemistry and ecosystems together at small scales, the campaign aims to improve climate forecasts. It also seeks to advance understanding of the ocean's carbon cycle and how marine ecosystems may respond to climate change.