Generation of ringlets

Abstract

A mechanism for the generation of ringlets (i.e., small cyclonic eddies (20–40 km) which have recently been observed on the periphery of warm-core rings) is proposed. The suggested process is examined analytically using a reduced gravity one-and-a-half-layer and two-and-a-half-layer model. The underlying hypothesis is that the ringlets are formed by the expulsion of fluid from the outer rim of the warm ring and that this expulsion is the result of an absorption of foreign water into the core of the ring. This nonlinear process is examined using the not-so-frequently used integrated angular momentum constraint as well as the familiar conservation of potential vorticity and mass. These constraints show that when the ring interacts with other bodies of water such as shelf water or the Gulf Stream, the shelf water is sucked into the ring in such a manner that the entire ring is capped. To conserve angular momentum, some other fluid must then be pushed out and it is argued that via instability of the ring's edge, this expulsion forms ringlets.