Monsoon trough of the summertime Asian monsoon is in its normal orientation (oriented east-southeast to west-northwest), tropical cyclones along its periphery will move with a westward motion. If it reverses its orientation, orienting southwest to northeast, tropical cyclones will move more poleward. Tropical cyclone tracks with S-shapes tend to be associated with reverse-oriented monsoon troughs. The South Pacific convergence zone and South American convergence zones are generally reverse oriented. The failure of the monsoon trough, or the ITCZ, to move south of the equator in the eastern Pacific Ocean and Atlantic Ocean during the southern hemisphere summer, is considered one of the
Mariana Trough Mariana Trough The Mariana Trough is an active back-arc basin in the western Pacific Ocean . It is an integral part of the Izu-Bonin-Mariana Arc system. The Mariana Trough stretches 1300 km from north to south, about the distance from Los Angeles CA to Portland OR, Tokyo, Japan to Seoul, Korea, or London, England to Rome, Italy. The Mariana Trough has roughly the dimensions and areal extent of Japan or California. The Trough is crudely crescent-shaped, opening on the south; it is bounded to the east by the active Mariana arc, to the west by the remnant arc of the