“The Agulhas Current flows southward along South Africa’s east coast and warms the air above it, making the KwaZulu-Natal coast warmer than other places at the same latitude.”

Warm water arrives from the east on the fast-moving Agulhas Current, which flows along the east coast of Africa. Meanwhile, the cooler, slower Benguela Current flows north along Africa’s southwestern coast. The convergence of two ocean currents—one warm and one cold—in the shallow waters of Agulhas Bank produces turbulent and unpredictable waters.

The current turns back on itself in a tight loop, called the Agulhas Current Retroflection, with most of its waters contained in this swift recurvature before they flow back into the South Indian Ocean. As the Agulhas Current flows south along the African east coast, it tends to bulge inshore frequently.

Especially for the southeast coast, the air masses that reach the continent accumulate heat and moisture by travelling from the Indian Ocean over the warm Agulhas Current towards the continent, favouring precipitation in that region. A reduction in the strength of the Agulhas Current is linked to a reduction in precipitation along the southeast coast. The sea surface temperatures (SSTs) of the Agulhas Current also impact South African precipitation indirectly.

Since the 1980s, the sea surface temperature of the Agulhas Current system has increased significantly. This is due to an increase of its transport in response to an augmentation in wind stress curl in the South Indian Ocean. The most important change is found in the Agulhas Current system, which has warmed by up to 1.5 °C since the 1980s.

Throughout the Agulhas system there is warming of 1 °C and moisture is advected downstream of the Agulhas Current and over the Agulhas bank. The Agulhas Current, located off the eastern coast of South Africa, is the largest western boundary current in the southern hemisphere and provides moisture to the atmospheric boundary layer via latent heat fluxes which are projected to increase significantly over western boundary systems as the climate system warms. The strongest temperatures are found over the Agulhas Current as it brings warm water from the equator towards the poles.

This warm Current creates a high temperature gradient with the surrounding ocean, leading to a large turbulent flux of moisture from ocean to atmosphere. I use high-resolution annual mean observations from satellites, atmospheric reanalysis, and the Weather Research and Forecasting (WRF) model to show that the warm core of the Agulhas Current drives a band of precipitation along the east coast of South Africa when the Current is adjacent to the coast. The higher temperature of the control simulation leads to cyclonic circulation anomalies and larger moisture flux anomalies from the Agulhas Current to the continent.

Our simulations show a significant increase in sea surface temperature and bottom temperature, but limited changes in primary production.

The Agulhas Current transports warm tropical Indian Ocean water southwards along the South African coast. It modulates the rainfall along the regions of South Africa by providing the latent heat of evaporation needed for onshore wind systems to pick up moisture and carry it inland.

The Agulhas Current transports warm tropical Indian Ocean water southwards along the South African coast. It modulates the rainfall along the east coast and interior regions of South Africa by providing the latent heat of evaporation needed for onshore wind systems to pick up moisture and carry it inland.

The warm tropical Agulhas Current provides large amounts of moisture, transported onshore by south-easterly trade winds during summer. As the trade wind shifts to north-westerly during winter, the moisture transport is reduced.

The Agulhas Current appears as a rapid flow 1500 kilometers long and 300 kilometers wide between the South African coast and the topographic high. Current profiles and maps of volume transport are used to trace the flow of water from the broad, shallow South Equatorial Current to the narrow, deep Agulhas Current where transports may be as high as 100 megatons/sec during the southern winter and 80 megatons/sec in summer.

The Agulhas current, transporting about 73 billion liters of water per second, is one of the most powerful ocean currents in the world. This warm water current runs down the east coast of southern Africa, before retroflecting back eastwards into the Indian Ocean.

The Agulhas Current is one of the world's most powerful ocean currents. Each second it transports up to 70 million cubic meters of warm, saline water southward along the southern African coast in the Indian Ocean.

Agulhas current: a warm, fast-moving high-saline current that moves southward down the east coast, its flow directed by topography.

The warm Agulhas Current flowing southward along South Africa's east coast, including KwaZulu-Natal, significantly warms the overlying air, contributing to higher coastal temperatures and increased humidity compared to the cooler Benguela-influenced west coast at similar latitudes. This effect is well-documented in oceanographic studies and explains the subtropical climate of KwaZulu-Natal despite its mid-latitude position.

The warmth of the Agulhas Current feeds moisture into the atmosphere, which influences rainfall patterns over South Africa's east coast. It also contributes to the humid subtropical climate of South Africa’s east coast. Coral Reefs thrive in the warm waters along the KwaZulu-Natal coast.

Anthropogenic climate change over the Agulhas Current has the potential to influence regional weather patterns and extreme events such as storms or flooding.

The second episode of our series aboard the vessel SA Agulhas II focuses on the Agulhas Current and its role in global ocean circulation. Scientists explain how the current not only affects South African weather but also has a global impact; the warm waters of the current have been linked to South African rainfall and floods.

Warming in the Agulhas Current system occurs for all months of the year, and warming is evident at the near-shore, north of Port St Johns.