Tomographic imagine of ionospheric structures and disturbances in the region of East-Asian equatorial anomaly

Jisheng Xu, Xiongbin Wu, Shuying Ma, Mao Tian, Shengbing Yu, K. C. Yeh, J. S. Franke, W. H. Tsaoi, K. H. Lin

Research output: Contribution to journalArticlepeer-review

Abstract

Experiments of ionospheric tomography at low latitudes along 120°E meridian and some findings from analyses of such experimental data are presented. An improved reconstruction algorithm of computerized ionospheric tomography is proposed. In this algorithm, both differential Doppler phase and differential Doppler frequency data are jointly used and the integral phase constants are determined in the reconstruction process. Our findings indicate that the reconstructed ionospheric equatorial anomaly crests usually show a tilt in rough alignment with the local geomagnetic field, coinciding with the feature predicted by the fountain mechanism. The crest locations are found to move daily in response to changes in equatorial electrodynamics. When the crest moves from one day to the next day, the tilting angle changes so as to be still aligned with the local magnetic field. It is statistically found that an equator-ward motion of the crests is accompanied with a latitudinal broadening of the crest region. The reconstructed images also indicate that the crest location determined by the maximum electron density often does not coincide with that determined by the vertical total electron content. Besides, a deep depletion of ionospheric electron density appeared just 20 minutes after sudden commencement of a moderate magnetic storm at geomagnetic latitudes around 10°N where equatorial anomaly crests usually sit. The depleted hole extends over both the bottom and top F-region, with a steep wall on its equatorial side. The present study demonstrates that ionospheric tomographic technology is very useful and effective to the investigation of the equatorial and low-latitude ionospheric structures and dynamics.

Original languageEnglish (US)
Pages (from-to)395-404
Number of pages10
JournalScience in China, Series E: Technological Sciences
Volume43
Issue number4
DOIs
StatePublished - Aug 2000

Keywords

  • Differential Doppler
  • Equatorial anomaly
  • Ionosphere
  • Ionospheric storm
  • Tomography

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)

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