Abstract
Some simple air-sea momentum transfer models, which include sea surface velocity and temperature, are considered for their effects on Gulf Stream rings. Perturbing the stress calculation with sea surface velocity results in a “top drag”, which causes interior motions to decay. Numerical experiments with equivalent barotropic quasi-geostrophic dynamics and reasonable estimates for the top drag suggest that this mechanism can amount for a significant fraction of observed isotherm subsidence rates in rings. Perturbing the stress calculation with a temperature sensitive drag coefficient produces a dipolar Ekman pumping field over a ring. For an eastward directed wind, the result is a tendency for the ring to self-propagate to the south. Integral constraints can be used to estimate the meridional propagation rate precisely, and for reasonable stress and thermal anomaly values, the estimate compares well with observations.
