Cyclonic and anticyclonic motion in the upper ocean

Upper ocean variability is highly energetic and contributes to key processes such as heat transport and water mass formation. Here, the distribution of ocean surface cyclonic and anticyclonic motion is computed from global drifter observations for scales from large eddies to submesoscale. Two zonal bands of small-scale motion are recovered: a known anticyclonic band at 30°–40° latitude, mostly wind-induced, and an unexpected cyclonic band at 10°–20° latitude. It is suggested that this is due to submesoscale processes related to salinity front instabilities. These results provide a first global view of the upper ocean including these motions.