Roles of Flow Braking, Plasmaspheric Virtual Resonances, and Ionospheric Currents in Producing Ground Pi2 Pulsations

Kazue Takahashi, Michael D. Hartinger, Massimo Vellante, Balázs Heilig, Robert L. Lysak, Dong Hun Lee, Charles W. Smith

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

In one model, Pi2 pulsations are driven pulse by pulse by fast mode pulses that are launched as periodic bursty bulk flows brake when they approach the Earth. We have examined this model by analyzing data from multiple spacecraft and ground magnetometers for a Pi2 pulsation event. During the event, which started at ∼2226 UT on 8 November 2014, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-D detected an ∼2-min-period plasma bulk flow oscillation in the near-Earth magnetotail, while THEMIS-E and Van Allen Probes-B, both located on the nightside just earthward of the electron plasmapause, detected a Pi2 pulsation consisting of a 10-mHz oscillation in the azimuthal component of the electric field and a 19-mHz oscillation in the compressional component of the magnetic field. On the ground, magnetic field oscillations containing both frequencies were observed both on the nightside and on the dayside. The nightside observations indicated that the pulsation had a radially standing structure, which is consistent with plasmaspheric virtual resonances (PVRs) excited in a magnetohydrodynamic simulation assuming an impulsive energy source. Cross-spectral analysis of the magnetotail flow oscillation and the Pi2 pulsation indicated low coherence between them. These results suggest that the flow oscillation contributed to the Pi2 pulsation as a broadband energy source and that only the spectral components matching the PVR frequencies were detected with well-defined frequencies. Ionospheric currents connected to the PVRs may be responsible for the appearance of the pulsation on the dayside.

Original languageEnglish (US)
Pages (from-to)9187-9203
Number of pages17
JournalJournal of Geophysical Research: Space Physics
Volume123
Issue number11
DOIs
StatePublished - Nov 2018

Bibliographical note

Funding Information:
K. T. was supported by NASA grants NNX15AI95G and NNX17AD34G. M. D. H. was supported by NASA grant NNX17AD35G. R. L. L. was supported NSF grant AGS-1558134. The International Space Science Institute, Bern, facilitated collaboration of K. T., M. V., B. H., R. L., and D. H. L. Data used in this study are available from the following sources: Van Allen Probes Science Operation Centers located at University of Iowa (http://emfisis.physics.uiowa.edu) and University of Minnesota (http://www.space.umn.edu/missions/rbspefw-home-university-of-minnesota), for RBSP; Space Science Laboratory, University of California, Berkeley (http://themis.ssl.berkeley.edu), for THEMIS; NOAA National Centers for Environmental Information (http://satdat.ngdc.noaa.gov), for GOES; Japan Aerospace Exploration Agency (https://darts.isas.jaxa.jp/stp/geotail/data.html), for Geotail; Mining and Geological Survey of Hungary (http://geofizika.canet.hu/plasmon/, contact heilig.balazs@mbfsz.gov.hu), for EMMA; Kakioka Magnetic Observatory (http://www.kakioka-jma.go.jp/en/), for the Kakioka magnetometer; World Data Center for Geomagnetism, Kyoto (http://wdc.kugi.kyoto-u.ac.jp), for the AL and AU indices; and the United States Geological Survey (https://geomag.usgs.gov/monitoring/observatories/), for the San Juan and Honolulu magnetometers. The source data used for illustrating the results of the numerical simulation are available by contacting K. T. (kazue.takahashi@jhuapl.edu).

Funding Information:
K. T. was supported by NASA grants NNX15AI95G and NNX17AD34G. M. D. H. was supported by NASA grant NNX17AD35G. R. L. L. was supported NSF grant AGS-1558134. The International Space Science Institute, Bern, facilitated collaboration of K. T., M. V., B. H., R. L., and D. H. L. Data used in this study are available from the following sources: Van Allen Probes Science Operation Centers located at University of Iowa (http://emfisis.physics.uiowa.edu) and University of Minnesota (http://www.space.umn.edu/ missions/rbspefw-home-university -of-minnesota), for RBSP; Space Science Laboratory, University of California, Berkeley (http://themis.ssl.berkeley.edu), for THEMIS; NOAA National Centers for Environmental Information (http://satdat.ngdc.noaa.gov), for GOES; Japan Aerospace Exploration Agency (https://darts.isas.jaxa.jp/stp/geotail/ data.html), for Geotail; Mining and Geological Survey of Hungary (http://geofizika.canet.hu/ plasmon/, contact heilig.balazs @mbfsz.gov.hu), for EMMA; Kakioka Magnetic Observatory (http://www.kakioka-jma.go.jp/en/), for the Kakioka magnetometer; World Data Center for Geomagnetism, Kyoto (http://wdc.kugi.kyoto-u.ac.jp), for the AL and AU indices; and the United States Geological Survey (https://geomag.usgs.gov/ monitoring/observatories/), for the San Juan and Honolulu magnetometers. The source data used for illustrating the results of the numerical simulation are available by contacting K. T. (kazue.takahashi@jhuapl.edu).

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