Large variations in the thermosphere and ionosphere during minor geomagnetic disturbances in April 2002 and their association with IMF B y

L. Goncharenko, J. Salah, G. Crowley, L. J. Paxton, Y. Zhang, A. Coster, W. Rideout, C. Huang, S. Zhang, B. Reinisch, V. Taran

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15 Citations (Scopus)

Abstract

We investigate the variations in the thermosphere and ionosphere using multi-instrument observations during the April 2002 period, with a particular focus on periods during small geomagnetic disturbances. Large and long-lasting reductions in the daytime electron density were observed at midlatitudes by incoherent scatter radars, ionosondes, and GPS receivers. These reductions reached 30-50% and were observed over an extended longitudinal area. They propagated to middle latitudes (35-40°N) in the case of a weak geomagnetic disturbance (Kp = 3-) and to low latitudes (0-10°N) in the case of a stronger disturbance (Kp = 5-). Data from the GUVI instrument aboard the TIMED satellite reveal a reduction in the daytime O/N2 ratio in the coincident area. Similar decreases are also predicted by the TIMEGCM/ASPEN model in both O/N2 ratio and electron density, though the magnitude of the decrease from the model is smaller than observed. We suggest that these ionospheric and thermospheric disturbances result from high-latitude energy input and efficient transport of regions with reduced O/N2 to lower latitudes. We discuss the possible role of a strong positive By component of the interplanetary magnetic field in the transport of regions with reduced O/N2.

Original languageEnglish
Article numberA03303
JournalJournal of Geophysical Research: Space Physics
Volume111
Issue number3
DOIs
Publication statusPublished - Mar 1 2006

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

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