Tropical Instability Wave Energetics: Observations from the Tropical Instability Wave Experiment

Abstract

Ocean velocity data from an array of subsurface moorings deployed from May 1990 to June 1991 during the Tropical Instability Wave Experiment are used to study the energetics of planetary waves in the vicinity of the equator at 140°W. Such waves, observed from August to December 1990, were initiated by barotropic instability arising primarily from the cyclonic shear region of the South Equatorial Current and Equatorial Undercurrent just north of the equator. Subsequently, local barotropic production continued to maintain and modulate these tropical instability waves through a combination of cyclonic shear and meridional velocity component divergence just north of the equator. The end of the wave season coincided with the propagation past the array of a large intraseasonal Kelvin wave.