ULF signals observed near the magnetopause
Abstract
The region near the magnetopause is rich in magnetic ULF fluctuations some of which are intrinsic to the magnetopause while others are incident from the magnetosheath. The magnetosheath is populated by fast magnetosonic and Alfvenic fluctuations generated at the bow shock and by locally excited mirror and ion cyclotron waves. The quasi-parallel shock is associated with turbulent magnetosheath fields. Slow magnetosonic modes may also be generated at the bow shock and have been reported just outside the magnetopause. Broadband fluctuations are observed in the magnetopause current layer for high magnetic shear and some evidence suggests that they are convecting filamentary current structures. These magnetopause fluctuations may be a fundamental property of the current layer.