Occurrence characteristics of electromagnetic ion cyclotron waves at sub-auroral Antarctic station Maitri during solar cycle 24

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dc.rights.license CC BY 4.0
dc.contributor.author Upadhyay, Aditi
dc.contributor.author Kakad, Bharati
dc.contributor.author Kakad, Amar
dc.contributor.author Omura, Yoshiharu
dc.contributor.author Sinha, Ashwini Kumar
dc.date.accessioned 2022-05-25T06:33:03Z
dc.date.available 2022-05-25T06:33:03Z
dc.date.issued 2020
dc.identifier.citation Earth, Planet & Space, v. 73, https://doi.org/10.1186/s40623-020-01157-7 en_US
dc.identifier.uri http://library.iigm.res.in:8080/xmlui/handle/123456798/123
dc.description.abstract We present a statistical study of electromagnetic ion cyclotron (EMIC) waves observed at Antarctic station (geographic 70.7◦ S, 11.8◦ E, L = 5) on quiet and disturbed days during 2011–2017. The data span a fairly good period of both ascending and descending phases of the solar cycle 24, which has witnessed extremely low activity. We noted EMIC wave occurrence by examining wave power in diferent frequency ranges in the spectrogram. EMIC wave occurrence during ascending and descending phases of solar cycle 24, its local time, seasonal dependence and durations have been examined. There are total 2367 days for which data are available. Overall, EMIC waves are observed for 3166.5 h (≈ 5.57% of total duration) which has contributions from 1263 days. We fnd a signifcantly higher EMIC wave occurrence during the descending phase (≈ 6.83%) as compared to the ascending phase (≈ 4.08%) of the solar cycle, which implies nearly a twofold increase in EMIC wave occurrence. This feature is attributed to the higher solar wind dynamic pressure during descending phase of solar activity. There is no evident diference in the percentage occurrence of EMIC waves on magnetically disturbed and quiet days. On ground, EMIC waves show marginally higher occurrence during winter as compared to summer. This seasonal tendency is attributed to lower electron densities and conductivities in the ionosphere, which can afect the propagation of EMIC waves through ionospheric ducts. In local time, the probability distribution function of EMIC wave occurrence shows enhancement during 11.7–20.7 LT (i.e., afternoon–dusk sector). Daily durations of EMIC waves are in the range of 5–1015 min and it is noted that the longer duration (240–1015 min) events are prevalent on quiet days and are mostly seen during the descending phase of solar cycle. en_US
dc.language.iso en en_US
dc.subject ULF wave en_US
dc.subject EMIC occurrence en_US
dc.subject Solar cycle en_US
dc.subject Induction coil magnetometer en_US
dc.title Occurrence characteristics of electromagnetic ion cyclotron waves at sub-auroral Antarctic station Maitri during solar cycle 24 en_US
dc.type Article en_US
dcterms.source https://doi.org/10.1186/s40623-020-01157-7


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