Variations of topside ionospheric electron density near the dawn terminator in relation to geomagnetic activity

Sunny W.Y. Tam, Chien Han Chen, Kaiti Wang

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A statistical study to determine the influence of geomagnetic disturbances on the ionosphere across the dawn terminator at subauroral and middle latitudes is performed, based on the vertical electron density profiles measured by the GPS Occultation Experiment aboard the FORMOSAT-3/COSMIC satellites from August 2006 to July 2009. Three ranges of solar zenith angles are adopted to characterize transitions between the pre- and post-dawn ionosphere. Results indicate opposing plasma density effects at the darkened and sunlit locations between 50° and 65° magnetic latitude (λm). The darkened topside ionosphere features density increases associated with geomagnetic activity, while density reductions mark its sunlit counterpart. The average electron peak density in the F2 region can increase by up to 44% in the darkened ionosphere and decrease by up to 20% in the sunlit ionosphere as Kp changes from 0-1 to 4-5. In the λm = 55°-65° range, the dominant contributors to the density perturbation are auroral electron precipitation for the darkened region and enhanced penetration electric fields for the sunlit region, with the transition occurring across the terminator local times. Dominance shifts first to electric fields at 50°-55°, then to aurora-induced neutral wind at 45°-50°, suggesting that during disturbed times electric fields seldom penetrate below λm = 50°. Findings presented in this statistical study should contribute to the study of space weather and the understanding of non-local influences of geomagnetic disturbances on topside dynamics.

Original languageEnglish
Article numberA31
JournalJournal of Space Weather and Space Climate
Volume7
DOIs
Publication statusPublished - 2017 Jan 1

Fingerprint

ionospheric electron density
electron density
ionospheres
ionosphere
electric field
electric fields
disturbances
COSMIC
disturbance
electron precipitation
electron
space weather
electron density profiles
occultation
aurora
zenith angle
zenith
plasma density
GPS
penetration

All Science Journal Classification (ASJC) codes

  • Atmospheric Science
  • Space and Planetary Science

Cite this

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title = "Variations of topside ionospheric electron density near the dawn terminator in relation to geomagnetic activity",
abstract = "A statistical study to determine the influence of geomagnetic disturbances on the ionosphere across the dawn terminator at subauroral and middle latitudes is performed, based on the vertical electron density profiles measured by the GPS Occultation Experiment aboard the FORMOSAT-3/COSMIC satellites from August 2006 to July 2009. Three ranges of solar zenith angles are adopted to characterize transitions between the pre- and post-dawn ionosphere. Results indicate opposing plasma density effects at the darkened and sunlit locations between 50° and 65° magnetic latitude (λm). The darkened topside ionosphere features density increases associated with geomagnetic activity, while density reductions mark its sunlit counterpart. The average electron peak density in the F2 region can increase by up to 44{\%} in the darkened ionosphere and decrease by up to 20{\%} in the sunlit ionosphere as Kp changes from 0-1 to 4-5. In the λm = 55°-65° range, the dominant contributors to the density perturbation are auroral electron precipitation for the darkened region and enhanced penetration electric fields for the sunlit region, with the transition occurring across the terminator local times. Dominance shifts first to electric fields at 50°-55°, then to aurora-induced neutral wind at 45°-50°, suggesting that during disturbed times electric fields seldom penetrate below λm = 50°. Findings presented in this statistical study should contribute to the study of space weather and the understanding of non-local influences of geomagnetic disturbances on topside dynamics.",
author = "Tam, {Sunny W.Y.} and Chen, {Chien Han} and Kaiti Wang",
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Variations of topside ionospheric electron density near the dawn terminator in relation to geomagnetic activity. / Tam, Sunny W.Y.; Chen, Chien Han; Wang, Kaiti.

In: Journal of Space Weather and Space Climate, Vol. 7, A31, 01.01.2017.

Research output: Contribution to journalArticle

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