SM006-0004
Characteristics of the EMIC waves Observed at the Indian Antarctic Station Maitri

Monday, 7 December 2020
Poster
Aditi Upadhyay1, Bharati A Kakad2, Amarkumar Kakad3 and Ashwini Kumar Sinha2, (1)Indian Institute of Geomagnetism, Mumbai, MAHARASHTRA, India, (2)Indian Institute of Geomagnetism, Navi Mumbai, India, (3)Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai, India
Abstract:
We present a comprehensive study of Electromagnetic Ion Cyclotron (EMIC) waves observed at Antarctic station, Maitri (geographic 70.7oS, 11.8oE, L = 5) during 2011-2017. The data spans fairly good period of both ascending and descending phase of the solar cycle 24, which has witnessed extremely low activity. Using the Induction Coil Magnetometer (ICM) data, we have performed the statistical analysis and determined the pattern (seasonal, diurnal, monthly and duration-wise) of occurrence of EMIC wave for quiet and disturbed days. Dependence of interplanetary parameters like solar wind dynamic pressure, density, velocity, and temperature on EMIC wave’s occurrence was explored. We found that solar wind pressure had a major role to play in controlling the ground occurrence of EMIC waves [Upadhyay et. al., 2020] [1].

Another aspect of the present study is related to the modulation of EMIC waves. The EMIC waves fall into Pc1-Pc2, frequency range and they are often modulated by longer and shorter period waves. Recently, such modulation is reported by Kakad et. al., 2019 [2] for a moderately disturbed day. They have performed the analysis of a single EMIC wave event occurred on 17 September 2011 and observed the presence of short (≈2.4 min) and long (≈39–69 min) periodicities. The analysis shows that the short periodicities are associated with the Pc5 Ultra Low Frequency (ULF) waves generated by magnetic field line oscillations, while long periodicities might be associated with the ring current drifting ions. It is believed that the process of structuring and formation of the envelopes of EMIC emissions is linked with the modulation of EMIC waves. In this context, to get the statistical picture we have analyzed the short and long period fluctuations for all the EMIC wave events. The results obtained from the study will be discussed in details.

References

  • Upadhyay, B. Kakad, A. Kakad, Y. Omura and A. K. Sinha, (2020). “Occurrence characteristics of electromagnetic ion cyclotron waves at sub-auroral Antarctic station Maitri during solar cycle 24”. Earth, Planets and Space, 72(1), 1-16.
  • Kakad, B. Kakad, Y.Omura, A. K. Sinha, A. Upadhyay, and R. Rawat, (2019). “Modulation of Electromagnetic Ion Cyclotron Waves by Pc5 ULF Waves and Energetic Ring Current Ions,” Journal of Geophysical Research: Space Physics, 124(3).
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