Physics of auroral phenomena : proceedings of the 38th annual seminar, Apatity, 2-6 march, 2015 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Издательство Кольского научного центра РАН, 2015. - 189 с. : ил., табл.

Strange VLF events at auroral latitudes The morning high-frequency “funny” hiss. The two-hours lasting VLF hiss burst at the untypically high frequency band (~ 4-10 kHz) was recorded on 8 December 2013 in the initial phase of the moderate magnetic storm (Fig. 6 ). The left panel shows the 24 hours spectrogram. The high-frequency “funny” hiss is seen in the early morning (00-03 UT) hours with temporal structure (the right panel in Fig. 6 ) differs from classical aurora! hiss which was recorded in this day at 18-19 UT. The frequencies of “funny hiss” were much higher than frequencies of typical daytime hiss observed at auroral and subauroral latitudes. The considered high-frequency “funny hiss” was left-hand polarized (in contrast to typical auroral hiss which is usually right-hand polarized), therefore the ionosphere exit point of these waves was located far from receiver. The wave arriving study showed the East-West direction. Thus, the “funny hiss” could be generated in the dayside magnetosphere, probably, inside or near the plasmapause by electron-cyclotron mechanism. But the possibility of this scenario and the wave propagation to the receiver is still open problem. Tw*feam8«K!r?Wne«>.tw>* Tire from!hastart time m rraules Figure 6 . The left panel 24-hours 1-11 kHz spectrogram on 8 December 2013; the right panel - 3-hours (00-03 UT) spectrogram of the “funny “hiss. Discussion and summery We presented here several new, previously unknown events of long-lasting non-typical quasi-periodic VLF emissions observed mainly in the winter season under quiet geomagnetic conditions, but after geomagnetic disturbances. That supports the idea of an internal source of these VLF emissions generation. The general behaviour of these VLF emissions could be interpreted as the self-oscillations of the magnetospheric maser [Bespalov, 1982; Bespalov and Trakhtengerts, 1986]. But the exact mechanism explaining the temporal dynamics and the wave spectral composition, especially a superposition of different emissions at different frequency, is still unknown. The application of the high-frequency filtering of impulsive atmospherics has revealed new dayside natural right-hand polarized emission at frequencies of -6-9 kHz observed mainly in the daytime The nature of these emissions is still unknown. Acknow ledgements. The N.K. work was partly supported by RFBR grant 13-05-00233. Список ли т ер атуры Bespalov, P.A. Self-excitation ofperiodic cyclotron instability regimes in a plasma magnetic trap. Physica Scripta 2/2,575-579.1982. Bespalov, P.A., Trakhtengerts, V.Yu. The cyclotron instability in the Earth radiation belts, in: Leontovich, M.A. (ed.), Reviews ofPlasma Physics, Plenum Publ.,N.Y. 10, 155-292. 1986. Manninen, J., Kleimenova, N.G., Kozyreva, O.V. New type of ensemble of quasi-periodic, long-lasting VLF emissions at the auroral zone //Ann. Geophys. V. 30. P. 1655-1660. 2012. Manninen, J., Kleimenova, N.G., Kozyreva, O.V., Bespalov, P.A., Kozlovsky, A.E. Non-typical ground-based quasi-periodic VLF emissions observed at L - 5.3 under quiet geomagnetic conditions at night // J. Atmosp. Solar-Terr. Phys. V. 99. P. 123-128.2013. Manninen, J., Kleimenova, N.G., Fedorenko, Yu.V., Bespalov, P.A., Turunen, T. New results of structured VLF emissions observed simultaneously at two closely located stations near L ~ 5.5 // Ann. Geophys. V. 32. P. 1163-1167. doi: 10.5194/angeo-32-1163-2014. 2014a. Manninen, J., Demekhov, A.G., Titova, E.E., Kozlovsky, A.E., Pasmanik, D.L. Quasiperiodic VLF emissions with short-period modulation and their relationship to whistlers: A case study // J. Geophys. Res. Space Physics. V. 119. P. 3544-3557. doi: 10.1002/2013JA019743. 2014b. Sazhin, S. S., Hayakawa, M. Periodic and quasiperiodic VLF emissions, J. Atmos. Terr. Phys., 56 ( 6 ), 735-753, 1994. Trakhtengerts, V.Y., Rycroft, M.J. Whistler and Alfven mode cyclotron masers in space, Cambridge University Press, pp. 354, 63