The existence and vertical structure of fast, eastward-moving disturbances in the equatorial troposphere

Abstract

Eastward phase propagation, at speeds faster than 30 m s-1, of a signal in the equatorial troposphere of the Eastern Pacific is detected, first in historical meteorological observations and then in more recent data. A first baroclinic mode vertical structure is identified with this signal in separate analyses based on linear theory and complex empirical orthogonal functions, respectively. This rapid, eastward signal is conceptualized as a far-field dispersion product of strong convection associated with the intraseasonal tropical oscillation in the Indian Ocean and Western Pacific.