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Statistical Properties of Quasi-periodic Electromagnetic Ion Cyclotron Waves: ULF Modulation Effects
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  • Muhammad Shahid,
  • Muhammad Fraz Bashir,
  • Anton V Artemyev,
  • Xiao-Jia Zhang,
  • Vassilis Angelopoulos,
  • Ghulam Murtaza
Muhammad Shahid
GC University Lahore

Corresponding Author:[email protected]

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Muhammad Fraz Bashir
University of California Los Angeles
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Anton V Artemyev
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Xiao-Jia Zhang
The University of Texas at Dallas
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Vassilis Angelopoulos
University of California Los Angeles
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Ghulam Murtaza
Government College University, Lahore
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Electromagnetic ion cyclotron (EMIC) waves effectively scatter relativistic electrons in the Earthâ\euro™s radiation belts and energetic ions in the ring current. Empirical models parameterizing EMIC wave characteristics are important elements of inner magnetosphere simulations. Two main EMIC wave populations included in such simulations are the population generated by plasma sheet injections and another population generated by magnetospheric compression due to solar wind. In this study, we investigate a third class of EMIC waves, generated by hot plasma sheet ions modulated by compressional ultra-low-frequency (ULF) waves. Such ULF-modulated EMIC waves are mostly observed on the dayside, between magnetopause and the outer radiation belt edge. We show that ULF-modulated EMIC waves are weakly oblique (with wave normal angle $\approx 20^\circ\pm10^\circ$) and narrow banded (with spectral width of $\sim 1/3$ of the mean frequency). We further construct an empirical model of EMIC wave characteristics as a function of $L$-shell and MLT. The low ratio of plasma frequency to electron gyrofrequency ($f_{pe}/f_{ce}\sim 5-10$) around the EMIC wave generation region does not allow these waves to scatter energetic electrons. However, these waves provide very effective (comparable to strong diffusion) quasi-periodic precipitation of plasma sheet protons.
22 Nov 2023Submitted to ESS Open Archive
22 Nov 2023Published in ESS Open Archive