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Propagation and evolution of electric fields associated with solar wind pressure pulses based on spacecraft and ground‐based observations
Author(s) -
Takahashi N.,
Kasaba Y.,
Nishimura Y.,
Shinbori A.,
Kikuchi T.,
Hori T.,
Ebihara Y.,
Nishitani N.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2017ja023990
Subject(s) - ionosphere , physics , noon , magnetosphere , electric field , geophysics , plasmasphere , local time , solar wind , poynting vector , computational physics , amplitude , magnetic field , atmospheric sciences , optics , statistics , mathematics , quantum mechanics
We investigate spatial and temporal evolution of large‐scale electric fields in the magnetosphere and ionosphere associated with sudden commencements (SCs) using multipoint equatorial magnetospheric (THEMIS, RBSP, and GOES) and ionospheric (C/NOFS) satellites with radars (SuperDARN). A distinct SC event on 17 March 2013 shows that the magnetospheric electric field in the equatorial plane propagates from dayside toward nightside as a fast‐mode wave. The ionospheric electric field responds ~41 s after the onset of dayside magnetospheric electric field, which can be explained by the propagation of the Alfvén wave along magnetic field lines. The wavelet analysis shows that the Alfvén wave is dominant in the plasmasphere. Poynting fluxes toward the ionosphere support these propagations. From a statistical analysis of response time, tailward propagation speed is estimated at about 1000–1100 km/s. We also statistically derive a spatial distribution and time evolution of the magnetospheric electric field in the dawn‐dusk direction ( E y ). Our result shows that negative E y (dawnward) propagates from noon toward the magnetotail, followed by positive E y (duskward). The propagation characteristics of electric fields in the equatorial plane depend on magnetic local time. At noon, negative E y lasts for about 1 min, and positive E y becomes dominant about 2 min after the SC onset. Negative E y soon attenuates in the nightside region, while the positive E y propagates fairly well to the premidnight or postmidnight regions while maintaining a certain amplitude. The enhancement of positive E y is due to the enhancement of magnetospheric convection associated with the main impulse of SCs.