Traveling magnetopause distortion related to a large-scale magnetosheath plasma jet: THEMIS and ground-based observations

Abstract

Here, we present a case study of THEMIS and ground-based observations on the dayside magnetopause, and geomagnetic field perturbations related to the interaction of an interplanetary directional discontinuity (DD), as observed by ACE, within the magnetosphere on 16 June 2007. The interaction resulted in a large-scale local magnetopause distortion of an 'expansion-compression-expansion' (ECE) sequence that lasted for 15 min. The compression was caused by a very dense, cold, and fast high-beta magnetosheath plasma flow, a so-called plasma jet, whose kinetic energy was approximately three times higher than the energy of the incident solar wind. The plasma jet resulted in the effective penetration of the magnetosheath plasma inside the magnetosphere. A strong distortion of the Chapman-Ferraro current in the ECE sequence generated a tripolar magnetic pulse 'decrease-peak-decrease' (DPD) that was observed at low and middle latitudes by the INTERMAGNET network of ground-based magnetometers. The characteristics of the ECE sequence and the spatial-temporal dynamics of the DPD pulse were found to be very different from any reported patterns of DD interactions within the magnetosphere. The observed features only partially resembled structures such as FTE, hot flow anomalies, and transient density events. Thus, it is difficult to explain them in the context of existing models.

arXiv comment24 pages, 6 figure, 3 tables

References in corpus (3)

• Magnetopause expansions for quasi-radial interplanetary magnetic field: THEMIS and Geotail observations
• Pressure balance at the magnetopause: Experimental studies
• A global study of hot flow anomalies using Cluster multi-spacecraft measurements

Cited by in corpus (6)

• Large-scale jets in the magnetosheath and plasma penetration across the magnetopause: THEMIS observations
• Dayside magnetospheric and ionospheric responses to a foreshock transient on June 25, 2008: 2. 2-D evolution based on dayside auroral imaging
• Transport and entry of plasma clouds/jets across transverse magnetic discontinuities: Three-dimensional electromagnetic particle-in-cell simulations
• Causes of jets in the quasi-perpendicular magnetosheath
• Tangential deflection and formation of counterstreaming flows at the impact of a plasma jet on a tangential discontinuity
• Finite-Larmor-radius equilibrium and currents of the Earth's flank magnetopause