A new NASA animation reveals how currents circulate, and their possible impact on climate change. James Lloyd investigates. This striking image of the North Atlantic Ocean is much more than just a pretty picture. It not only shows circulation patterns in detail, but the methods used to create the animation will soon enable scientists to make more accurate predictions about climate change. The picture you see is a still frame from an animation created by NASA’s Scientific Visualization Studio.
The white lines in the image show the surface currents while the blue shading in the ocean indicates the depth of the seafloor below – the darker areas represent deeper waters. The Gulf Stream is clearly visible as a streak of white that curls around the tip of Florida before working its way up the east coast of the USA. The Vincent van Gogh-like swirls are features known as eddies – looping currents, typically 10 to 100km in diameter that can persist for months. These are formed when meanders in the current trap water that’s either warmer or cooler than the water around it. This water can completely separate from the main current, forming a circulation pattern similar to the weather systems that are seen in the atmosphere.
This animation was created using data from the ECCO2 (Estimating the Circulation and Climate of the Ocean, Phase II) project. ECCO2 uses a state-of-the-art numerical model that combines observations from a variety of sources, such as satellites and ocean instruments, at a high enough resolution to show smaller features such as eddies. “Surprisingly, eddies in the oceans are much smaller than their atmospheric counterparts,” says Patrick Heimbach, an oceanographer at the Massachusetts Institute of Technology (MIT) who is involved with the ECCO2 project. “Therefore, ocean models require much higher resolutions to resolve oceanic weather. Computer simulations which resolve eddies have only become possible in recent years, with the advent of high-performance supercomputers.” Eddies are important because they play a key role in moving heat and carbon around the oceans.
Research has shown that eddies in the Southern Ocean around Antarctica transport heat polewards; this heat can ultimately be released into the atmosphere, affecting large-scale wind patterns. A better understanding of these processes will, therefore, help researchers to predict the evolution of the oceans, and our planet’s climate, over the coming decades.