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Ionospheric HF pump wave triggering of local auroral activation

Research output: Contribution to journalJournal article

Published

  • N. F. Blagoveshchenskaya
  • V. A. Kornienko
  • T. D. Borisova
  • B. Thidé
  • Mike J. Kosch
  • M. T. Rietveld
  • E. V. Mishin
  • R. Yu. Lukýanova
  • O. A. Troshichev
Journal publication date12/2001
JournalJournal of Geophysical Research
Journal numberA12
Volume106
Number of pages19
Pages29071-29089
Original languageEnglish

Abstract

Experimental results from ionospheric HF pumping experiments in the nightside auroral E region above Tromsø are reported. We found intriguing evidence that a modification of the ionosphere-magnetosphere coupling, due to the effects of powerful HF waves beamed into an auroral sporadic E layer, can lead to a local intensification of the auroral activity. Summarizing multi-instrument observations during two consecutive nights, one can distinguish the following peculiarities related to this auroral activation: a modification of the auroral arc and its breakup above Tromsø, local changes in the horizontal currents above Tromsø, a burst-like increase of the electron density and temperature, a large increase in the ion temperature in a wide altitude range and in the north-south component of the electric field, distinctive features in dynamic HF radio scatter Doppler spectra, pump-induced electron precipitation, and substorm activation exactly above Tromsø. We discuss the modification of the ionosphere-magnetosphere coupling in terms of the excitation of a turbulent Alfvén boundary layer between the base of the ionosphere (∼100 km) and the level of sharp increase of the Alfvén velocity (at heights up to one Earth radius), and the formation of a local magnetospheric current system. The results suggest that a possible triggering of local auroral activation requires specific geophysical conditions.

Bibliographic note

Copyright (2001) American Geophysical Union.