An interesting form of “zipper-like” magnetosonic waves consisting of two bands of interleaved periodic rising-tone spectra was newly observed by the Van Allen Probes, the Time History of Events and Macroscale Interactions during Substorms (THEMIS), and the Magnetospheric Multiscale (MMS) missions. The two discrete bands are distinct in frequency and intensity; however, they maintain the same periodicity which varies in space and time, suggesting that they possibly originate from one single source intrinsically. In one event, the zipper-like magnetosonic waves exhibit the same periodicity as a constant-frequency magnetosonic wave and an electrostatic emission, but the modulation comes from neither density fluctuations nor ULF waves. A statistical survey based on 3.5 years of multisatellite observations shows that zipper-like magnetosonic waves mainly occur on the dawnside to noonside, in a frequency range between 10 fcp and fLHR. The zipper-like magnetosonic waves may provide a new clue to nonlinear excitation or modulation process, while its cause still remains to be fully understood.
Bibliographical noteFunding Information:
J.L. and J.B. would like to acknowledge NASA grants NNX13AI61G and NNX14AN85G. W.L., Q.M., and R.M.T. acknowledge EMFISIS subaward 1001057397:01, the ECT subaward 13?041, and NSF Geospace Environment Modeling grant AGS-1405054. This work is also supported by JHU/APL contracts 967399 and 921647 under NASA's prime contract NAS5-01072. The RBSPICE instrument is supported by JHU/APL subcontract 937836 to the New Jersey Institute of Technology under NASA prime contract NAS5-01072. The work at the University of Minnesota was supported by JHU/APL contract UMN 922613 under NASA contract JHU/APL NAS5-01072. We thank the entire MMS team and instrument leads for data access and support. The French involvement (SCM instruments) on THEMIS and MMS is supported by CNES, CNRS-INSIS, and CNRS-INSU. We acknowledge the Van Allen Probes data from the EMFISIS instrument obtained from https://emfisis.physics.uiowa.edu/data/index, the EFW instrument data obtained from http://www.space.umn.edu/missions/rbspefw-home-university-of-minnesota/, the ECT instrument data obtained from https://www.rbsp-ect.lanl.gov/, and the RBSPICE data obtained from http://rbspice.ftecs.com/. We acknowledge the MMS data obtained from https://lasp.colorado.edu/mms/sdc/public/ and the THEMIS data obtained from http://themis.ssl.berkeley.edu/index.shtml. We also thank the World Data Center for Geomagnetism, Kyoto for providing SYM-H and AE indexes (http://wdc.kugi.kyoto-u.ac.jp/aeasy/index.html). We thank V. Angelopoulos (University of California, Los Angeles), S. Wellenzohn (Space Research Institute, Austrian Academy of Sciences), and L. J. Lanzerotti (New Jersey Institute of Technology) for their great contributions.
©2017. American Geophysical Union. All Rights Reserved.
- magnetosonic wave
- radiation belt