Caribbean Sea eddies inferred from TOPEX/POSEIDON altimetry and a 1/6° Atlantic Ocean model simulation

Abstract

Large cyclonic and anticyclonic eddies are found in the Caribbean Sea. Analysis of sea level data from the TOPEX/POSEIDON altimeter shows that the eddies are quite regular, appearing at near 3-month intervals west of the southern Lesser Antilles. These eddies progress westward at average speeds of 12 cm s-1, growing in amplitude up to 20 cm. Many eddies dissipate in the coastal waters of Nicaragua a half year after they appear. A 1/6° × 1/6° general circulation model of the Atlantic is shown to reproduce major features of the eddy life cycle, including their amplitudes, temporal scales, and propagation speed. Analysis of the model output further suggests that the eddies are mainly limited to the thermocline and above, with little phase lag in the vertical. The simulated eddies have sufficiently strong currents that the horizontal gradient of total vorticity changes sign, suggesting that conversions from mean to eddy kinetic energy may be contributing to their growth. Analysis of the simulation links eddies in the Caribbean with eddies formed outside the Caribbean at the confluence of the North Brazil Current and North Equatorial Countercurrent systems. Copyright 1999 by the American Geophysical Union.