Drifting ELF/VLF Emissions Observed at Low Latitude Ground Station During Geomagnetic Storm

作者：Singh A K^*; Singh Shubha; Singh R P

来源：Earth, Moon, and Planets, 2010, 106(2-4): 119-132.

DOI：10.1007/s11038-010-9353-4

• Drifting VLF emissions
• Whistler-mode waves
• Geomagnetic storm

We have reported for the first time total seven strong events of drifting ELF/VLF discrete emissions observed on 28th-29th April, 1990 in the pre-midnight sector at Varanasi (Geomag. lat. 14 degrees 55'N, long. 154 degrees E, L = 1.07). The events exhibit a regular increasing as well as decreasing frequency drifts and are mainly discrete periodic emissions of riser, faller and hook types observed during a geomagnetic storm period, with minimum Dst-index -98 nT and K(p)-index >= 5. The frequency drift in ELF/VLF emissions at low latitudes seems to be a rare phenomenon. The repetition period and the frequency drift rate have been evaluated for all the recorded events. The frequency drifts have been interpreted in terms of a combined effect of L-shell drift of interacting energetic electrons and the change in convection electric fields during the storm developments. The computed maximum spectral power density < B(f)(2)>(max) of the wave varies between 1.8 x 10(-21) and 4.08 x 10(-22) Gauss(2)/Hz, whereas frequency drift rates are in agreement with the observed values.

• 出版日期2010-7