Subtropical Gyre

A subtropical gyre is a large, wind-driven anticyclonic circulation that fills each subtropical ocean basin, rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern. The trade winds on the equatorward side and the westerlies on the poleward side impose a negative wind-stress curl that drives Ekman convergence and downwelling at the center, raising sea level into a dome. Sverdrup balance sets the broad equatorward interior transport, returned by an intense, narrow western boundary current such as the Gulf Stream or Kuroshio. The gyres set ocean heat transport and the oligotrophic subtropical waters.