The 10- to 20- day westward propagating mode and ' Breaks in the Monsoons'.

Abstract

Utilizes surface pressure data records for a 40-year period (1933 to 1972). The dominant transient modes of the wave number frequency spectra of surface pressure along the latitudes of the monsoon trough (i.e., 20o to 30oN) are determined from a longitude time composite of roughly 3 months of surface pressure data for 10 separate episodes of Breaks in the monsoons. The period of Breaks in the monsoon rainfall is shown to coincide with a pressure rise associated with the arrival of a ridge of the dominant modes over the reference origin. In over 70% of he cases examined the arrival of the ridge coincides with a period of the observed Breaks in the monsoon. -Authors.