合唱波次波元之地方時區分布與背景參數分析;Local Time Distribution of Chorus Wave Subelements and Analysis of Background Parameters

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Title:	合唱波次波元之地方時區分布與背景參數分析;Local Time Distribution of Chorus Wave Subelements and Analysis of Background Parameters
Authors:	林玟均;Lin, Wun-Jyun
Contributors:	太空科學與工程學系
Keywords:	合唱波;次波元;輻射帶電子;非線性波粒交互作用;Chorus wave;Subelement;Radiation belt electrons;Nonlinear wave-particle interactions
Date:	2025-07-08
Issue Date:	2025-10-17 11:14:25 (UTC+8)
Publisher:	國立中央大學
Abstract:	哨聲模合唱波是一種常見於地球磁層的電磁波。典型的合唱波事件由多個離散且同調的波元所組成，每個波元內又包含更細微的結構，稱為次波元。本研究分析次波元振幅與波傳播角度、持續時間、頻率變化、掃頻率與合唱波次波元個數之間的關係，發現振幅與持續時間之間存在反比平方根關係，並得到次波元個數對正規化的頻率變化量除以振幅平方根高度正相關的結果。本研究也分析這些次波元的持續時間，探討其與當地背景參數之間的關係，包含高能電子溫度、溫度非均向性、高能電子密度與總磁場強度，以及對不同地方時區的分布。研究結果顯示，次波元的平均持續時間分布主要受到高能電子溫度的影響與地方時區並無顯著相關。透過四分衛距分組後的相關性分析顯示，溫度是在背景參數之間對持續時間影響最大的參數；進一步根據溫度分組過後發現，密度與持續時間呈現正相關性，在低溫的情況下尤為顯著。進行由於合唱波在輻射帶電子的加速與損失過程中扮演關鍵角色，本研究對次波元特性的探討，有助於更深入理解合唱波的精細結構及其與高能電子之間的交互作用。;Whistler-mode chorus waves are a type of electromagnetic wave commonly observed in Earth′s magnetosphere. A typical chorus event is composed of multiple discrete and coherent wave elements, each of which contains finer-scale structures called subelements. This study analyzes the relationships between subelement amplitude and parameters such as wave propagation angle, duration, frequency variation, chirping rate, and the number of chorus subelements. The results reveal an inverse square root relationship between amplitude and duration, and a strong positive correlation between the number of subelements and the normalized frequency variation divided by the square root of amplitude. In addition, we examine the durations of these subelements in relation to local plasma parameters and assess their dependence on magnetic local time. Our results show that the average duration of subelements does not exhibit a significant dependence on magnetic local time, but is mainly influenced by the temperature of energetic electrons. Further correlation analyses using quartile grouping show that temperature is the most influential factor among the background parameters affecting the duration. After grouping by temperature, a positive correlation between density and duration is observed, especially under low-temperature conditions. Correlation analyses also reveal that this temperature is closely linked to the number of subelements within each chorus element. As chorus waves play a key role in both the acceleration and loss of radiation belt electrons, this investigation into subelement characteristics provides deeper insight into the fine-scale dynamics of chorus waves and their interactions with energetic electrons.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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