Changing transport and curvature bias: A new type of meandering in the Florida Straits

Abstract

Meanders in strong, inertial flows are generally asymmetric. Florida Current meanders with periods of 7–10 days and flows that tend to meander offshore when strong and onshore when weak, which we call type A, have been widely documented. We find a countertrend in the Florida Current data collected under the aegis of Subtropical Atlantic Climate Studies: a type B meandering where flows tend to meander offshore when weak and onshore when strong. On time scales of several months and depending on the strength of the flow, the tendency displays a largely one‐sided preference for either the onshore or the offshore component of the meander. In particular, the data reveal a negative curvature bias during the generally higher transports in spring and summer when most of the speed cores were inshore, and a positive curvature bias during lower transports in fall and winter when most speed cores were offshore. The data show that any use of cross‐channel sea level slope to estimate the transport would generally overestimate the weaker, but underestimate the stronger flows. Type B meander is interpreted as one of three types embodied in a meandering equation in which curvature changes are controlled primarily by the Coriolis effect of downstream acceleration and hence by that of changing transport. In this light the bimodal paths of the Kuroshio south of Japan is a type B meander.