Thev-components of the trade-wind systems in the North and South Pacific and Atlantic Oceans undergo surges of above- and below-normal convergence. These surges have a typical time scale of the order of a year and coincide with long-term fluctuations of precipitation in the inter-tropical convergence zone (ITCZ). There is now evidence that these surges are tied to the “southern oscillation”, i. e. the surface pressure oscillation between South Pacific and South Indian Ocean. Also a strong correlation between the convergence surges of the Atlantic trade-wind systems and the quasi-biennial oscillation (QBO) of equatorial winds is suggested.