Discussion of Meridional Propagation Mechanism of Quasi-40-Day Oscillation

Based on researches made by the author in recent years, discussion is made of the quasi-40-day oscillation (QDO) nature and its characteristic propagation, with emphasis on the Southern Hemisphere mid-latitude quasi-periodic cold air forcing on the tropical atmosphere quasi-40-day oscillation along with its effect upon the Northern Hemisphere summer monsoon. It is proposed that the interaction between, or lateral coupling of, meridional circulation systems may serve as the mechanism of the oscillation propagation in a meridional direction.