Paper#: 4
Poster #: 28
Session Name: Poster Session 1
Room: East Ballroom
Day: Tuesday
Time: 10:10 a.m.-Noon
Abstract Title: Ionospheric HF Pump Wave Triggering of Auroral Activation on October 2, 1998
PresentSurname: Blagoveshchenskaya, N.
All Authors: N. Blagoveshchenskaya , V.A. Kornienko, M.T. Rietveld, B. Thide'
Abstract : The analysis of multi-instrument ground-based observations during the Tromso HF pumping experiment on October 2,1998 is performed. HF pump waves were injected into night-side auroral F2 layer from 19:00 UT along magnetic field line direction with a 8 min on,7 min off pump cycle. Experimental results from a bistatic HF Doppler scatter measurements at the London--Tromso--St.Petersburg path, EISCAT UHF radar, IMAGE magnetometer network and IMP 8 satellite, have been used to find the evidence that auroral activation on October 2, 1998 was initiated by effects due to HF pump waves. IMAGE magnetometer data show that a large auroral activation located above the heated volume, started at 19:30 UT. From HF Doppler measurements the signals scattered from artificial field-aligned irregularities can be recognized during heater-on periods 19:00--19:08 and 19:15--19:23 UT. The turning on of the Tromso heater at 19:30 UT lead to the generation of very intense small-scale ionospheric wave disturbance with periods of 7-8 min that can be the ionospheric signature of the internal atmospheric gravity wave (AGW). It is most likely that the AGW was launched by the strong heater-enhanced electric fields through the frictional heating. From EISCAT UHF radar data in the field-aligned direction one can see the strong enhancements of electron and ion temperatures in a wide altitude range, the generation of the strong pump-induced upward ion flows closely related to heater-on periods. The obtained results suggest that a triggering of the auroral activation requires specific geophysical conditions, namely, the presence of the accumulation of energy in the magnetospheric tail.