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A Foreshock Bubble Driven by an IMF Tangential Discontinuity: 3D Global Hybrid Simulation
Author(s) -
Wang ChihPing,
Wang Xueyi,
Liu Terry Z.,
Lin Yu
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl093068
Subject(s) - foreshock , classification of discontinuities , physics , discontinuity (linguistics) , solar wind , magnetic field , geophysics , perpendicular , bubble , upstream (networking) , mechanics , computational physics , geology , seismology , mathematical analysis , geometry , mathematics , quantum mechanics , aftershock , computer network , computer science
Foreshock bubbles (FBs) have been observed upstream of solar wind tangential discontinuities (TDs). A hypothesized mechanism is that foreshock ions with gyroradii larger than the TD thickness may move to upstream side of TDs and generate FBs. In this study, we present the very first three‐dimensional global hybrid simulation of an FB driven by a TD. After the TD encounters the ion foreshock, plasma and magnetic field perturbations are generated upstream of the TD. These perturbations are characteristically consistent with the observed TD‐driven FBs, confirming that TDs can form FBs. We further analyze the initial perpendicular temperature increase initiating the FB and compare the temperature structure with that from tracing test‐particles in static TD electric and magnetic fields. The structure can be explained by the perpendicular velocity change of foreshock ions with large gyroradii as they encounter the magnetic field direction change across the TD, which supports the hypothesized mechanism.