Spinup of a Submesoscale Eddy in the TOGA COARE Intensive Flux Array during the Spindown of an Intense Eastward Jet

Abstract

During the TOGA COARE Intensive Observing Period, an energetic, surface-intensified, submesoscale cyclonic eddy was observed in the near-equatorial western Pacific warm pool. The eddy appeared to have been generated as part of the spindown of a strong eastward surface jet forced by the December 1992 westerly wind burst. Because of its potential impacts on the long-term heat, salt, and momentum budgets of the warm pool, the authors provide a thorough description of the evolution of the surface jet and the development of the eddy in the present study. Both the isopycnal surface fit and the zeroth-order dynamic balance confirm the existence of the eddy. Surface layer convergence and northward inertial motion are suggested to be the main causes of the negative eddy vorticity, and it is likely that the eddy drew its energy from the decaying surface jet. This study indicates that in the near-equatorial region the inertial motion has a decreasing meridional spatial scale with time, (?t)?1, due to the ? effect, which increases the Rossby number of the decaying jet and generates the nonlinearity.