@article{ac98a45b6f2a478c988f1732a5e45ee8,
title = "A Systematic Study in Characteristics of Lower Band Rising-Tone Chorus Elements",
abstract = "Chorus waves are usually generated outside the plasmapause in the equatorial region of the magnetosphere. The discrete characteristics of chorus elements are quantified by the three parameters: lasting time, frequency bandwidth, and repetition period. A systematic study in the lasting time and frequency bandwidth in terms of background plasma and magnetic fields has not been performed in the past. Here we use burst mode waveform data from the Time History of Events and Macroscale Interaction during Substorms (THEMIS) probes and the random forest method of machine learning and Pearson's correlation analysis to investigate which background plasma and magnetic field parameter is dominant over the lasting time and frequency bandwidth. We find that the temperature is the most important parameter that controls the lasting time. The lasting time is shorter when this temperature is higher. We also find that the normalized bandwidth by the local electron cyclotron frequency is controlled by the number density of energetic electrons. The normalized bandwidth is wider when this number density is larger. These results can be well explained by the threshold and optimum wave amplitudes for the nonlinear generation of chorus waves (Omura & Nunn, 2011, https://doi.org/10.1029/2010JA016280). The findings derived from this analysis can be used to serve as a guideline for a deep understanding of the generation mechanism of chorus elements and help choose input for a modeling of wave-particle interactions in the radiation belts.",
keywords = "chorus waves, energetic particles, frequency shift, lasting time, temperature",
author = "Shue, {Jih Hong} and Yasuhiro Nariyuki and Yuto Katoh and Shinji Saito and Yoshiya Kasahara and Hsieh, {Yi Kai} and Shoya Matsuda and Yoshitaka Goto",
note = "Funding Information: This work was supported by grant MOST 107-2111-M-008-031 to the National Central University through the Ministry of Science and Technology and by the NICT invitation program for foreign researchers to Toyama University through the National Institute of Information and Communications Technology. The THEMIS data used to identify chorus elements and estimate background plasma and magnetic fields were obtained from http://themis.ssl.berkeley.edu/data/themis/. We acknowledge NASA contract NAS5-02099, and V. Angelopoulos, H. U. Auster, W. Baumjohann, J. W. Bonnell, C. W. Carlson, J. P. McFadden, K. H. Glassmeier, D. Larson, O. Le Contel, the late R. P. Lin, F. S. Mozer, and the late A. Roux for the use of the THEMIS data. We thank Taiyun Wei and Viliam Simko for the use of the corrplot program in version 0.77 in the R package obtained from http://CRAN.R-project.org/package=corrplot to create the correlation plot for this paper. Funding Information: This work was supported by grant MOST 107‐2111‐M‐008‐031 to the National Central University through the Ministry of Science and Technology and by the NICT invitation program for foreign researchers to Toyama University through the National Institute of Information and Communications Technology. The THEMIS data used to identify chorus elements and estimate background plasma and magnetic fields were obtained from http://themis.ssl.berkeley.edu/data/themis/ . We acknowledge NASA contract NAS5‐02099, and V. Angelopoulos, H. U. Auster, W. Baumjohann, J. W. Bonnell, C. W. Carlson, J. P. McFadden, K. H. Glassmeier, D. Larson, O. Le Contel, the late R. P. Lin, F. S. Mozer, and the late A. Roux for the use of the THEMIS data. We thank Taiyun Wei and Viliam Simko for the use of the corrplot program in version 0.77 in the R package obtained from http://CRAN.R‐project.org/package=corrplot to create the correlation plot for this paper. Publisher Copyright: {\textcopyright}2019. American Geophysical Union. All Rights Reserved.",
year = "2019",
month = nov,
day = "1",
doi = "10.1029/2019JA027368",
language = "English",
volume = "124",
pages = "9003--9016",
journal = "Journal of Geophysical Research: Space Physics",
issn = "2169-9380",
publisher = "Wiley-Blackwell",
number = "11",
}