Anomalous Reconnection Layer at Earth's Dayside Magnetopause
| Autor: | Christopher T. Russell, G. Paschmann, Ian J. Cohen, Stein Haaland, Richard E. Denton, K. J. Trattner, Daniel J. Gershman, Tai Phan, S. A. Fuselier, James L. Burch, Bengt U. Ö. Sonnerup, Barbara L. Giles |
|---|---|
| Přispěvatelé: | Sonnerup, B. U. Ö., 2 Thayer School of Engineering Dartmouth College Hanover NH USA, Phan, T., 3 Space Sciences Laboratory University of California Berkeley CA USA, Fuselier, S. A., 4 Southwest Research Institute San Antonio TX USA, Haaland, S., 6 Birkeland Centre for Space Science University of Bergen Bergen Norway, Denton, R. E., 9 Department of Physics and Astronomy Dartmouth College Hanover NH USA, Burch, J. L., Trattner, K. J., 10 LASP University of Colorado Boulder CO USA, Giles, B. L., 11 NASA Goddard Space Flight Center Greenbelt MD USA, Gershman, D. J., Cohen, I. J., 13 The Johns Hopkins University Applied Physics Laboratory Laurel MD USA, Russell, C. T., 14 Department of Earth Planetary and Space Sciences University of California Los Angeles CA USA |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | e2021JA029678 Journal of Geophysical Research (JGR): Space Physics |
| Popis: | Observations by the Magnetospheric Multiscale spacecraft (MMS) of an unusual layer, located between the dayside magnetosheath and the magnetosphere, alternating with encounters with the magnetosheath during an extended time period between December 31, 2015 and January 01, 2016, when the interplanetary magnetic field was strongly southward and the Earth's dipole tilt large and negative, are presented. It appears to have been magnetically connected to both magnetosphere and magnetosheath. The layer appears to be located mostly on closed field lines and was bounded by a rotational discontinuity (RD) at its magnetosheath edge and by the magnetosphere on its earthward side. A separatrix layer, with heated magnetosheath electrons streaming unidirectionally along the field lines, was present sunward of the RD. We infer that the layer was started by a dominant reconnection site well north of the spacecraft and that it may have gained additional width, from a large drop in solar wind density and ram pressure, which preceded the beginning of the event by more than an hour. Relative to the magnetosheath, in which the magnetic field was strongly southward, this unusual layer was characterized by a less southward, more dawnward magnetic field of lower magnitude. The plasma density and flow speed in the region were lower than in the magnetosheath, albeit with Alfvénic jetting occurring at the magnetosheath edge as well as at the magnetospheric edge of the layer. The closing of the magnetic field lines requires the existence of another reconnection site, located southward/tailward of MMS. Key Points: Magnetopause encounter for strongly southward interplanetary magnetic field, low solar wind Alfvén Mach number, and large dipole tilt. Persistent and broad magnetopause layer with magnetospheric O+ and heated magnetosheath plasma. Inferred dominant reconnection site near northern cusp, far from the Magnetospheric Multiscale spacecraft location. MPE NASA http://dx.doi.org/10.13039/100000104 Norwegian Research Council http://dx.doi.org/10.13039/501100005416 |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|