EFFECTS OF SUBSURFACE OCEAN DYNAMICS ON INSTABILITY WAVES IN THE TROPICAL PACIFIC

Tropical instability waves in a primitive equation model of the tropic al Pacific Ocean, forced with analyzed wind stresses updated daily, sh ow unexpectedly close phase correspondence with observation through th e latter half of 1992. This suggests that these waves are not pure ins tabilities developing from infinitesimal disturbances, but that their phases and phase speeds are at least partially determined by the wind stress forcing. To quantify and explain this observation, we perfomed several numerical experiments, which indicate that remotely forced Ros sby waves can influence both the phase and phase speed of tropical ins tability waves. We suggest that a remote wind forcing determines the h igh model/observation phase correspondence of tropical instability wav es through a relatively realistic simulation of equatorial Kelvin and Rossby wave activity.