Detection of Hertz Frequency Multiharmonic Field Line Resonances at Low-L (L = 1.1–1.5) During Van Allen Probe Perigee Passes

F. R. Lena; L. G. Ozeke; J. R. Wygant; S. Tian; A. W. Breneman; I. R. Mann

doi:10.1029/2020GL090632

Detection of Hertz Frequency Multiharmonic Field Line Resonances at Low-L (L = 1.1–1.5) During Van Allen Probe Perigee Passes

F. R. Lena
, L. G. Ozeke
, J. R. Wygant
, S. Tian
, A. W. Breneman
, I. R. Mann

Physics and Astronomy (Twin Cities)

Research output: Contribution to journal › Article › peer-review

5 Scopus citations

Abstract

We present new and previously unreported in situ observations of Hertz frequency multiharmonic mode field line resonances detected by the Electric Field and Waves instrument on-board the NASA Van Allen probes during low-L perigee passes. Spectral analysis of the spin-plane electric field data reveals the waves in numerous perigee passes, in sequential passes of probes A and B, and with harmonic frequency structures from ∼0.5 to 3.5 Hz which vary with L-shell, altitude, and from day-to-day. Comparing the observations to wave models using plasma mass density values along the field line given by empirical power laws and from the International Reference Ionosphere model, we conclude that the waves are standing Alfvén field line resonances and that only odd-mode harmonics are excited. The model eigenfrequencies are strongly controlled by the density close to the apex of the field line, suggesting a new diagnostic for equatorial ionospheric density dynamics.

Original language	English (US)
Article number	2020GL090632
Journal	Geophysical Research Letters
Volume	48
Issue number	1
DOIs	https://doi.org/10.1029/2020GL090632
State	Published - Jan 16 2021

Bibliographical note

Funding Information:
I. R. Mann is supported by a Discovery grant from Canadian NSERC. This research was supported by funding from the Canadian Space Agency through a Geospace Observatory (GO) Canada Science and Applications grant. The authors acknowledge the WDC for Geomagnetism, Kyoto University, Japan, for the geomagnetic indices (http://wdc.kugi.kyoto-u.ac.jp/). The authors also acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb service and OMNI data.

Funding Information:
I. R. Mann is supported by a Discovery grant from Canadian NSERC. This research was supported by funding from the Canadian Space Agency through a Geospace Observatory (GO) Canada Science and Applications grant. The authors acknowledge the WDC for Geomagnetism, Kyoto University, Japan, for the geomagnetic indices ( http://wdc.kugi.kyoto-u.ac.jp/ ). The authors also acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb service and OMNI data.

Publisher Copyright:
© 2020. American Geophysical Union. All Rights Reserved.

Keywords

field line resonance
ionosphere
magneto-seismology
magnetosphere
plasmasphere
standing Alfvén waves

Publisher link

10.1029/2020GL090632

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@article{1632bc04fba54c7b9f42d57b686bc49c,

title = "Detection of Hertz Frequency Multiharmonic Field Line Resonances at Low-L (L = 1.1–1.5) During Van Allen Probe Perigee Passes",

abstract = "We present new and previously unreported in situ observations of Hertz frequency multiharmonic mode field line resonances detected by the Electric Field and Waves instrument on-board the NASA Van Allen probes during low-L perigee passes. Spectral analysis of the spin-plane electric field data reveals the waves in numerous perigee passes, in sequential passes of probes A and B, and with harmonic frequency structures from ∼0.5 to 3.5 Hz which vary with L-shell, altitude, and from day-to-day. Comparing the observations to wave models using plasma mass density values along the field line given by empirical power laws and from the International Reference Ionosphere model, we conclude that the waves are standing Alfv{\'e}n field line resonances and that only odd-mode harmonics are excited. The model eigenfrequencies are strongly controlled by the density close to the apex of the field line, suggesting a new diagnostic for equatorial ionospheric density dynamics.",

keywords = "field line resonance, ionosphere, magneto-seismology, magnetosphere, plasmasphere, standing Alfv\&\#x00E9;n waves",

author = "Lena, \{F. R.\} and Ozeke, \{L. G.\} and Wygant, \{J. R.\} and S. Tian and Breneman, \{A. W.\} and Mann, \{I. R.\}",

note = "Funding Information: I. R. Mann is supported by a Discovery grant from Canadian NSERC. This research was supported by funding from the Canadian Space Agency through a Geospace Observatory (GO) Canada Science and Applications grant. The authors acknowledge the WDC for Geomagnetism, Kyoto University, Japan, for the geomagnetic indices (http://wdc.kugi.kyoto-u.ac.jp/). The authors also acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb service and OMNI data. Funding Information: I. R. Mann is supported by a Discovery grant from Canadian NSERC. This research was supported by funding from the Canadian Space Agency through a Geospace Observatory (GO) Canada Science and Applications grant. The authors acknowledge the WDC for Geomagnetism, Kyoto University, Japan, for the geomagnetic indices ( http://wdc.kugi.kyoto-u.ac.jp/ ). The authors also acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb service and OMNI data. Publisher Copyright: {\textcopyright} 2020. American Geophysical Union. All Rights Reserved.",

year = "2021",

month = jan,

day = "16",

doi = "10.1029/2020GL090632",

language = "English (US)",

volume = "48",

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T1 - Detection of Hertz Frequency Multiharmonic Field Line Resonances at Low-L (L = 1.1–1.5) During Van Allen Probe Perigee Passes

AU - Lena, F. R.

AU - Ozeke, L. G.

AU - Wygant, J. R.

AU - Tian, S.

AU - Breneman, A. W.

AU - Mann, I. R.

N1 - Funding Information: I. R. Mann is supported by a Discovery grant from Canadian NSERC. This research was supported by funding from the Canadian Space Agency through a Geospace Observatory (GO) Canada Science and Applications grant. The authors acknowledge the WDC for Geomagnetism, Kyoto University, Japan, for the geomagnetic indices (http://wdc.kugi.kyoto-u.ac.jp/). The authors also acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb service and OMNI data. Funding Information: I. R. Mann is supported by a Discovery grant from Canadian NSERC. This research was supported by funding from the Canadian Space Agency through a Geospace Observatory (GO) Canada Science and Applications grant. The authors acknowledge the WDC for Geomagnetism, Kyoto University, Japan, for the geomagnetic indices ( http://wdc.kugi.kyoto-u.ac.jp/ ). The authors also acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb service and OMNI data. Publisher Copyright: © 2020. American Geophysical Union. All Rights Reserved.

PY - 2021/1/16

Y1 - 2021/1/16

N2 - We present new and previously unreported in situ observations of Hertz frequency multiharmonic mode field line resonances detected by the Electric Field and Waves instrument on-board the NASA Van Allen probes during low-L perigee passes. Spectral analysis of the spin-plane electric field data reveals the waves in numerous perigee passes, in sequential passes of probes A and B, and with harmonic frequency structures from ∼0.5 to 3.5 Hz which vary with L-shell, altitude, and from day-to-day. Comparing the observations to wave models using plasma mass density values along the field line given by empirical power laws and from the International Reference Ionosphere model, we conclude that the waves are standing Alfvén field line resonances and that only odd-mode harmonics are excited. The model eigenfrequencies are strongly controlled by the density close to the apex of the field line, suggesting a new diagnostic for equatorial ionospheric density dynamics.

AB - We present new and previously unreported in situ observations of Hertz frequency multiharmonic mode field line resonances detected by the Electric Field and Waves instrument on-board the NASA Van Allen probes during low-L perigee passes. Spectral analysis of the spin-plane electric field data reveals the waves in numerous perigee passes, in sequential passes of probes A and B, and with harmonic frequency structures from ∼0.5 to 3.5 Hz which vary with L-shell, altitude, and from day-to-day. Comparing the observations to wave models using plasma mass density values along the field line given by empirical power laws and from the International Reference Ionosphere model, we conclude that the waves are standing Alfvén field line resonances and that only odd-mode harmonics are excited. The model eigenfrequencies are strongly controlled by the density close to the apex of the field line, suggesting a new diagnostic for equatorial ionospheric density dynamics.

KW - field line resonance

KW - ionosphere

KW - magneto-seismology

KW - magnetosphere

KW - plasmasphere

KW - standing Alfvén waves

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