Local time distribution of low and middle latitude ground magnetic disturbances at sawtooth injections of 18-19 April 2002

Kentarou Kitamura, Hideaki Kawano, Shin Ichi Ohtani, Akimasa Yoshikawa, Kiyohumi Yumoto

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

[1] During a magnetic storm of 18 April 2002, quasi-periodic variations of the low-energy electron flux were observed by the LANL satellites at geosynchronous orbit; this phenomenon has been called the "sawtooth event." During this event, on the ground, magnetic bays and Pi 2 pulsations took place corresponding to each enhancement of the particle flux, and they had features typical to usual substorms. However, unlike typical substorms, the ACE satellite observed no apparent northward turnings of the IMF corresponding to the sawtooth event. In this study, we used ground magnetic data from middle- and low-latitude stations which are distributed widely in the longitudinal direction, selected from the CPMN (Circum-Pan Pacific Magnetometer Network) and INTERMAGNET stations and compared the magnetic variations during the sawtooth event with that of the typical substorm (Lester et al., 1984). We found that the local time distribution of the polarization axis of the Pi 2 pulsations show a good agreement with that for a typical substorm, except that the local time width of the expected current wedge was 12 hours. On the other hand, the H component is predominant in the amplitude of the magnetic bay on the ground; the distribution of the H component also suggests a 12-hour-wide current wedge, which did not develop much in time. From these features, it is suggested that a current wedge was formed during this sawtooth event, and it generated the Pi 2 pulsations on the ground. However, the local time width of the current wedges is much wider than typical substorms, and its uniqueness causes the ground features different from typical substorm-associated magnetic variations on the ground.

Original languageEnglish
Article numberA07208
JournalJournal of Geophysical Research: Space Physics
Volume110
Issue numberA7
DOIs
Publication statusPublished - Jan 1 2005

Fingerprint

magnetic disturbances
tropical regions
wedges
Satellites
injection
Fluxes
disturbance
orbits
magnetic variations
Magnetometers
Orbits
electrons
Polarization
stations
Electrons
Advanced Composition Explorer
energy
IMF
geosynchronous orbits
magnetometer

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Cite this

Local time distribution of low and middle latitude ground magnetic disturbances at sawtooth injections of 18-19 April 2002. / Kitamura, Kentarou; Kawano, Hideaki; Ohtani, Shin Ichi; Yoshikawa, Akimasa; Yumoto, Kiyohumi.

In: Journal of Geophysical Research: Space Physics, Vol. 110, No. A7, A07208, 01.01.2005.

Research output: Contribution to journalArticle

@article{abebe9375a3445ffbff8b6a6a0d7acaf,
title = "Local time distribution of low and middle latitude ground magnetic disturbances at sawtooth injections of 18-19 April 2002",
abstract = "[1] During a magnetic storm of 18 April 2002, quasi-periodic variations of the low-energy electron flux were observed by the LANL satellites at geosynchronous orbit; this phenomenon has been called the {"}sawtooth event.{"} During this event, on the ground, magnetic bays and Pi 2 pulsations took place corresponding to each enhancement of the particle flux, and they had features typical to usual substorms. However, unlike typical substorms, the ACE satellite observed no apparent northward turnings of the IMF corresponding to the sawtooth event. In this study, we used ground magnetic data from middle- and low-latitude stations which are distributed widely in the longitudinal direction, selected from the CPMN (Circum-Pan Pacific Magnetometer Network) and INTERMAGNET stations and compared the magnetic variations during the sawtooth event with that of the typical substorm (Lester et al., 1984). We found that the local time distribution of the polarization axis of the Pi 2 pulsations show a good agreement with that for a typical substorm, except that the local time width of the expected current wedge was 12 hours. On the other hand, the H component is predominant in the amplitude of the magnetic bay on the ground; the distribution of the H component also suggests a 12-hour-wide current wedge, which did not develop much in time. From these features, it is suggested that a current wedge was formed during this sawtooth event, and it generated the Pi 2 pulsations on the ground. However, the local time width of the current wedges is much wider than typical substorms, and its uniqueness causes the ground features different from typical substorm-associated magnetic variations on the ground.",
author = "Kentarou Kitamura and Hideaki Kawano and Ohtani, {Shin Ichi} and Akimasa Yoshikawa and Kiyohumi Yumoto",
year = "2005",
month = "1",
day = "1",
doi = "10.1029/2004JA010734",
language = "English",
volume = "110",
journal = "Journal of Geophysical Research",
issn = "0148-0227",
publisher = "American Geophysical Union",
number = "A7",

}

TY - JOUR

T1 - Local time distribution of low and middle latitude ground magnetic disturbances at sawtooth injections of 18-19 April 2002

AU - Kitamura, Kentarou

AU - Kawano, Hideaki

AU - Ohtani, Shin Ichi

AU - Yoshikawa, Akimasa

AU - Yumoto, Kiyohumi

PY - 2005/1/1

Y1 - 2005/1/1

N2 - [1] During a magnetic storm of 18 April 2002, quasi-periodic variations of the low-energy electron flux were observed by the LANL satellites at geosynchronous orbit; this phenomenon has been called the "sawtooth event." During this event, on the ground, magnetic bays and Pi 2 pulsations took place corresponding to each enhancement of the particle flux, and they had features typical to usual substorms. However, unlike typical substorms, the ACE satellite observed no apparent northward turnings of the IMF corresponding to the sawtooth event. In this study, we used ground magnetic data from middle- and low-latitude stations which are distributed widely in the longitudinal direction, selected from the CPMN (Circum-Pan Pacific Magnetometer Network) and INTERMAGNET stations and compared the magnetic variations during the sawtooth event with that of the typical substorm (Lester et al., 1984). We found that the local time distribution of the polarization axis of the Pi 2 pulsations show a good agreement with that for a typical substorm, except that the local time width of the expected current wedge was 12 hours. On the other hand, the H component is predominant in the amplitude of the magnetic bay on the ground; the distribution of the H component also suggests a 12-hour-wide current wedge, which did not develop much in time. From these features, it is suggested that a current wedge was formed during this sawtooth event, and it generated the Pi 2 pulsations on the ground. However, the local time width of the current wedges is much wider than typical substorms, and its uniqueness causes the ground features different from typical substorm-associated magnetic variations on the ground.

AB - [1] During a magnetic storm of 18 April 2002, quasi-periodic variations of the low-energy electron flux were observed by the LANL satellites at geosynchronous orbit; this phenomenon has been called the "sawtooth event." During this event, on the ground, magnetic bays and Pi 2 pulsations took place corresponding to each enhancement of the particle flux, and they had features typical to usual substorms. However, unlike typical substorms, the ACE satellite observed no apparent northward turnings of the IMF corresponding to the sawtooth event. In this study, we used ground magnetic data from middle- and low-latitude stations which are distributed widely in the longitudinal direction, selected from the CPMN (Circum-Pan Pacific Magnetometer Network) and INTERMAGNET stations and compared the magnetic variations during the sawtooth event with that of the typical substorm (Lester et al., 1984). We found that the local time distribution of the polarization axis of the Pi 2 pulsations show a good agreement with that for a typical substorm, except that the local time width of the expected current wedge was 12 hours. On the other hand, the H component is predominant in the amplitude of the magnetic bay on the ground; the distribution of the H component also suggests a 12-hour-wide current wedge, which did not develop much in time. From these features, it is suggested that a current wedge was formed during this sawtooth event, and it generated the Pi 2 pulsations on the ground. However, the local time width of the current wedges is much wider than typical substorms, and its uniqueness causes the ground features different from typical substorm-associated magnetic variations on the ground.

UR - http://www.scopus.com/inward/record.url?scp=33746337889&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33746337889&partnerID=8YFLogxK

U2 - 10.1029/2004JA010734

DO - 10.1029/2004JA010734

M3 - Article

AN - SCOPUS:33746337889

VL - 110

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

SN - 0148-0227

IS - A7

M1 - A07208

ER -