A Statistical Study of Easterly Waves in the Western Pacific: July–December 1964

Abstract

The period July?December 1964 in the tropical western Pacific was marked by strong fluctuations in the meridional wind component with periods ranging from 4?6 days. This paper describes an intensive study of these disturbances, using spectrum-analysis techniques on time series of radiosonde data. Two types of disturbances appear to be involved. One of these, prevalent at Canton Island, is characterized by upward phase propagation in the lower troposphere and downward phase propagation above 200 mb. It has previously been suggested that this wave may be the tropospheric manifestation of the mixed Rossby- gravity wave. A second type of disturbance, prevalent at stations further west, is marked by an absence of vertical phase propagation. Latent heat release may be important in its energetics.