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Transmission of large‐amplitude ULF waves through a quasi‐parallel shock at Venus
Author(s) -
Shan Lican,
Lu Quanming,
Wu Mingyu,
Gao Xinliang,
Huang Can,
Zhang Tielong,
Wang Shui
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019396
Subject(s) - physics , shock wave , amplitude , bow shock (aerodynamics) , venus , oblique shock , bow wave , magnetic field , solar wind , polarization (electrochemistry) , shock (circulatory) , moving shock , geophysics , microseism , optics , computational physics , mechanics , geology , seismology , astrobiology , medicine , chemistry , quantum mechanics
There exist large‐amplitude ultralow frequency (ULF) waves in the upstream region of a quasi‐parallel shock, which are excited due to the reflected ions by the shock. These waves are then brought back to the shock by the solar wind, and at last they coalesce and merge with the shock. In this paper, with the magnetic field measurements from Venus Express, for the first time we observe the transmission of large‐amplitude ULF waves from the upstream region to the downstream under quasi‐parallel shock conditions. These waves exist in both the upstream and downstream regions of the Venusian bow shock, which have the similar characteristics: their peak frequencies are 0.04–0.05 Hz in the spacecraft frame, their propagation angles do not change greatly, they have left‐hand polarization with respect to the mean magnetic field in the spacecraft frame, and they also have a large compressibility. We conclude that they are magnetosonic waves. The generation mechanism of such waves at the Venusian bow shock is also discussed in the paper.