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Ion-Scale Structure in Mercury's Magnetopause Reconnection Diffusion RegionThe strength and time dependence of the electric field in a magnetopause diffusion region relate to the rate of magnetic reconnection between the solar wind and a planetary magnetic field. Here we use approximately 150 milliseconds measurements of energetic electrons from the Mercury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft observed over Mercury's dayside polar cap boundary (PCB) to infer such small-scale changes in magnetic topology and reconnection rates. We provide the first direct measurement of open magnetic topology in flux transfer events at Mercury, structures thought to account for a significant portion of the open magnetic flux transport throughout the magnetosphere. In addition, variations in PCB latitude likely correspond to intermittent bursts of approximately 0.3 to 3 millivolts per meter reconnection electric fields separated by approximately 5 to10 seconds, resulting in average and peak normalized dayside reconnection rates of approximately 0.02 and approximately 0.2, respectively. These data demonstrate that structure in the magnetopause diffusion region at Mercury occurs at the smallest ion scales relevant to reconnection physics.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Gershman, Daniel J. (Maryland Univ. College Park, MD, United States)
Dorelli, John C. (NASA Goddard Space Flight Center Greenbelt, MD United States)
DiBraccio, Gina A. (Maryland Univ. Baltimore County Baltimore, MD, United States)
Raines, Jim M. (Michigan Univ. Ann Arbor, MI, United States)
Slavin, James A. (Michigan Univ. Ann Arbor, MI, United States)
Poh, Gangkai (Michigan Univ. Ann Arbor, MI, United States)
Zurbuchen, Thomas H. (Michigan Univ. Ann Arbor, MI, United States)
Date Acquired
March 31, 2017
Publication Date
June 20, 2016
Publication Information
Publication: Geophysical Research Letters
Volume: 43
Issue: 12
ISSN: 0094-8276
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
Funding Number(s)
Distribution Limits