KINEMATICS OF A WARM-CORE DIPOLE RING

The remote sensing and in situ data used by Hooker and Brown [1994] to establish the dipole identity of warm core ring (WCR) 82-B is reexami ned. It is found that a rotating barotropic modon [Mied er al., 1992] can be constructed with the same dipole rotation rate, center-to-cente r vortex separation distance, and peak anticyclonic vorticity as those of WCR 82-B. The model-derived velocity field is used to deform an ar ray of material lines during a rotation period when the dipole is evid ent in the imagery and agreement between the model and the imagery is good. Specifically, it is observed that at the end of the imaging peri od, the surface tracer assumes a skewed dipole appearance, in which th e line of centers is not perpendicular to the separatrix. Moreover, th e separatrix morphology is qualitatively reproduced. Finally, the cycl one assumes an axisymmetric form. An attempt to derive qualitatively s imilar signatures using only monopole forcing yields results dissimila r from both the advanced very high resolution radiometer imagery and t hose obtained with the dipole, further confirming the underlying dipol e character of WCR 82-B.