||A rotational feature that (a) breaks off of an ocean gyre or large current (such as
the Gulf Stream) and (b) persist autonomously for some period (from days to months)
at sizes of 20 kilometers to 500 kilometers. These eddies play an important role in
ocean mixing—and in sheltering and acting as nursery waters for biota. The most energetic
eddies are at the smaller end of the spatial scale. The larger eddies (called mesoscale
eddies) are slower moving, but they persist for many months and are ubiquitous in
the global oceans. Mesoscale Eddies are most prevalent in the North Atlantic and North
Pacific, but they can occur in all oceans.