TY - JOUR
T1 - Longitudinal Extent of Magnetospheric ELF/VLF Waves using Multipoint PWING Ground Stations at Subauroral Latitudes
AU - Takeshita, Yuhei
AU - Shiokawa, Kazuo
AU - Ozaki, Mitsunori
AU - Manninen, Jyrki
AU - Oyama, Shin Ichiro
AU - Connors, Martin
AU - Baishev, Dmitry
AU - Kurkin, Vladimir
AU - Oinats, Alexey
N1 - Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Magnetospheric extremely low frequency/very low frequency (ELF/VLF) waves are plasma waves emitted from high-energy electrons in the magnetosphere. These waves have received much attention, as they contribute to the acceleration and loss of relativistic electrons in the radiation belts through wave-particle interactions. The longitudinal extent of ELF/VLF waves has not been well-understood, although the extent is important in quantitative evaluation of relativistic electron variations. In this study, we analyzed data from continuous ground-based simultaneous observations of ELF/VLF waves over a 2-month period in November and December of 2017, using six loop antennas located at roughly equal intervals around the north geomagnetic pole at ∼60° magnetic latitudes. We estimated the longitudinal extent of magnetospheric ELF/VLF waves based on their occurrence rate. Our results showed that the ELF/VLF wave occurrence rate differed by twofold to threefold, depending on the longitudes of the observation sites. We explain this difference in terms of longitudinal differences in the ionosphere's magnetic field intensity, possibly due to the electron loss that occurs during the bounce motion at longitudes of small magnetic field intensity. Based on our statistical analysis, we estimated the typical longitudinal extent of ELF/VLF waves as ∼76°. Time series analysis results showed that the large longitudinal extent of the ELF/VLF waves occurs frequently during the main phase of geomagnetic storms and is also associated with substorms represented by the auroral electrojet index.
AB - Magnetospheric extremely low frequency/very low frequency (ELF/VLF) waves are plasma waves emitted from high-energy electrons in the magnetosphere. These waves have received much attention, as they contribute to the acceleration and loss of relativistic electrons in the radiation belts through wave-particle interactions. The longitudinal extent of ELF/VLF waves has not been well-understood, although the extent is important in quantitative evaluation of relativistic electron variations. In this study, we analyzed data from continuous ground-based simultaneous observations of ELF/VLF waves over a 2-month period in November and December of 2017, using six loop antennas located at roughly equal intervals around the north geomagnetic pole at ∼60° magnetic latitudes. We estimated the longitudinal extent of magnetospheric ELF/VLF waves based on their occurrence rate. Our results showed that the ELF/VLF wave occurrence rate differed by twofold to threefold, depending on the longitudes of the observation sites. We explain this difference in terms of longitudinal differences in the ionosphere's magnetic field intensity, possibly due to the electron loss that occurs during the bounce motion at longitudes of small magnetic field intensity. Based on our statistical analysis, we estimated the typical longitudinal extent of ELF/VLF waves as ∼76°. Time series analysis results showed that the large longitudinal extent of the ELF/VLF waves occurs frequently during the main phase of geomagnetic storms and is also associated with substorms represented by the auroral electrojet index.
KW - ELF/VLF wave
KW - chorus wave
KW - ground-based network observations
KW - longitudinal extent
KW - magnetosphere
KW - plasma wave
UR - http://www.scopus.com/inward/record.url?scp=85076209508&partnerID=8YFLogxK
U2 - 10.1029/2019JA026810
DO - 10.1029/2019JA026810
M3 - Journal Article
AN - SCOPUS:85076209508
SN - 2169-9380
VL - 124
SP - 9881
EP - 9892
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 12
ER -