Anticyclonic eddies and Kuroshio Meander Formation

A meander‐formation mechanism of the Kuroshio that involves anticyclonic eddies propagating from the Kuroshio Extension, is presented using the analysis of observations of the TOPEX/POSEIDON (T/P) altimeter data and in‐situ data. Support of the mechanism comes also from a numerical simulation. In October 1997, a current meter mooring over the Izu Ridge at 500‐m‐depth captured large velocity fluctuations of about 50 cm s−1 that were associated with a strong anticyclonic eddy. The observations from T/P show that the anticyclonic eddy propagated westward and collided with the Kuroshio off Kyushu. At collision, the anticyclonic eddy coupled with a cyclonic circulation accompanied by a small meander and formed a vortex pair. They were then advected downstream and finally formed a large‐meander‐like path off the south coast of Honshu. The meander lasted for a few months. Subsequently, the anticyclonic eddy was detached, and the meander grew smaller in amplitude. Numerical experiments successfully simulate this interaction between the Kuroshio and anticyclonic eddies.