Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 18, issue 2
Ann. Geophys., 18, 252–256, 2000
https://doi.org/10.1007/s00585-000-0252-2
© European Geosciences Union 2000
Ann. Geophys., 18, 252–256, 2000
https://doi.org/10.1007/s00585-000-0252-2
© European Geosciences Union 2000

  29 Feb 2000

29 Feb 2000

Letter to the editor: Electric field fluctuations (25-35 min) in the midnight dip equatorial ionosphere

J. Hanumath Sastri1, H. Luhr2, H. Tachihara3, T. -I. Kitamura3, and J. V. S. V. Rao1 J. Hanumath Sastri et al.
  • 1Indian Institute of Astrophysics, Bangalore 560 034, India
  • E-mail: jhs@iiap.ernet.in
  • 2GeoForschungsZentrum, Potsdam, Germany
  • 3Department of Earth and Planetary Sciences, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
  • Correspondence to: J. Hanumath Sastri

Abstract. Measurements with a HF Doppler sounder at Kodaikanal (10.2°N, 77.5°E, geomagnetic latitude 0.8°N) showed conspicuous quasi-periodic fluctuations (period 25-35 min) in F region vertical plasma drift, Vz in the interval 0047-0210 IST on the night of 23/24 December, 1991 (Ap = 14, Kp < 4-). The fluctuations in F region vertical drift are found to be coherent with variations in Bz (north-south) component of interplanetary magnetic field (IMF), in geomagnetic H/X components at high-mid latitude locations both in the sunlit and dark hemispheres and near the dayside dip equator, suggestive of DP2 origin. But the polarity of the electric field fluctuations at the midnight dip equator (eastward) is the same as the dayside equator inferred from magnetic variations, contrary to what is expected of equatorial DP2. The origin of the coherent occurrence of equatorial electric field fluctuations in the DP2 range of the same sign in the day and night hemispheres is unclear and merits further investigations.

Key words: Ionosphere (electric fields and currents; equatorial ionosphere; ionosphere-magnetosphere interactions)

Publications Copernicus
Download
Citation