For microscopic plants to live in the upper layers of the ocean, something must stir sunken nutrients back to the surface. Satellite data have revealed that some of this agitating is done by vast waves that traverse the oceans, US researchers now announce 1 .
Wind stirs the water, and deep water wells up around coastlines and close to the poles.
Uz and his colleagues now suggest that some of the missing mixing could be a result of 'Rossby waves', which were recently shown to correspond to an increase in the amount of chlorophyll on the ocean's surface 2 . Rossby waves are produced by the Earth's rotation, and travel westwards around the planet. At only a few centimetres deep, they're not exactly a surfer's dream. They travel at only about 10 centimetres per second, and so take months or years to cross an ocean. But what they lack in height and speed, they make up for in width.