... The high-altitude cusp, which is often called the exterior cusp , can be considered to be a part of the magnetospheric boundary layer system. ... The low-altitude cusp is the dayside region in which the entry of magnetosheath plasma to low altitudes is most direct. ... The magnetosheath plasma penetrating into the low-altitude cusp (and the surrounding low-altitude boundary layer regions) is responsible for , e.g., part of the dayside auroral precipitation . ... solar wind variations . ... Res. ...