Discreet probes have been dropped every summer for thirty years, recording water temperatures in the middle of the Southern Ocean. This exceptional database, built up over time, now enables detailed mapping of the deep layers of an ocean that is rarely observed, yet where powerful currents and energetic eddies circulate.
By Laurie Henry
In the high latitudes of the southern hemisphere, much of the heat exchange between the ocean and the atmosphere takes place in the Southern Ocean, an ocean that is difficult to access and still largely unknown. This vast basin surrounds the Antarctic continent and is home to one of the major currents of global ocean circulation and the most powerful on the planet, the circumpolar current.
To better understand this key region, researchers have been conducting continuous monitoring since 1994. Each Antarctic summer, oceanographic campaigns have collected thousands of temperature profiles. The results, published in the journal Earth System Science Data, present a unique database of observations documenting the thermal dynamics of the strategic area between New Zealand and Antarctica, with direct application potential in global climate modeling.
A strategic ocean lock at the heart of the global climate
The area between Aotearoa/New Zealand and the Ross Sea is a pivotal zone for the global climate. This narrow passage controls a key part of ocean transport and crosses the Antarctic Circumpolar Current (ACC), the main vector of heat, salt, and nutrients to Antarctica. This area plays a vital role in the functioning of global thermohaline circulation: the waters that pass through it influence not only Antarctic marine ecosystems, but also global energy exchanges between the atmosphere and the oceans.
This region is particularly complex because the presence of the Campbell Plateau locally disrupts the current’s path, generating multiple fronts and intense dynamic structures. Researchers have focused their efforts on this strategic area, which is regularly visited by the research vessels Italica, Araon, and Laura Bassi. During 30 campaigns conducted between 1994 and 2024, scientists collected temperature profiles using XBT (expendable bathythermographs) probes, dropped at 20-km intervals. These profiles, with a maximum vertical resolution of 65 centimeters, cover a maximum depth of 760 meters, where much of the heat exchange in the area takes place.