The turbulent motion of the plasma compressed behind the Earth's bow shock can cause magnetospheric field lines at the magnetopause to develop localized regions or negative curvature. These regions are unstable with respect to interchange, which can lead to significant transport of mass and energy across the magnetopause. The rate at which magnetosheath plasma crosses the magnetopause is estimated to be of order 1026 s-1, which is consistent with estimates based on observations. ¿ American Geophysical Union 1995