Maximum Likelihood Parameter Estimation and Simulation of Damped-Type ULF Waves Using a Workstation

使用工作站进行阻尼型 ULF 波的最大似然参数估计和仿真

• 批准号: 05640488
• 负责人: ITONAGA Masahiro
• 金额: $ 1.22万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05640488/
• 关键词: workstation; damped-type ULF wave; parameter estimation; maximum likelihood method; modified Pisarenko method; piecewise cubic polynomial; PCP filter; simulation; ULF波動; 最尤パラメータ推定; データ平滑化; 離散的周波数構造; 磁力線共鳴; 電離層電気伝導度

Various computer programs for data processing have been developed on a workstation, and parameter estimations and simulations of damped-type ULF waves have been per-formed using the workstation. Research results are as follows : 1.While a method for fitting a piecewise cubic polynomial (PCP) to a sequence of data, which corresponds to a nonlinear lowpass filter and is named a PCP filter, is accompanied with a parameter mu determing the degree of smoothing, the relation between mu and its cutoff frequency has been found.The PCP filter is effective in separating Psc's from main impulses of SSC's. 2. Although a modified Pisarenko method (MPM) is inferior in estimation ability to the maximum likelihood method (MLM), it is one of the methods with the highest perfor-mance except for the MLM and is much superior in computational cost to the MLM.It has been used in the analysis of the Psc's. 3. The shape of the waveform of low-latitude and equatorial Psc's is consistently ordered by local time ; it is steeper near noon and has a more moderate slope near midnight. They have globally almost identical dominant frequencies which agree well with those of Pi2's. These indicate that the Psc's are not cavity-mode oscillations but compressional hydromagnetic (HM) waves propagating from dayside to nightside. 4. The self-consistent ionospheric boundary conditions, which de-scribe the interaction between HM waves and the anisotropically conducting ionosphere, have been derived in the form convenient for the eigenmode analysis of coupled HM waves in the magnetosphere-ionosphere system.

在工作站上开发了各种数据处理程序，并利用该工作站进行了阻尼型超低频波的参数估计和模拟。研究结果如下：1.当数据序列拟合分段三次多项式（PCP）时，对应于一个非线性低通滤波器，称为PCP滤波器，它带有一个决定平滑程度的参数μ，并找到了μ与其截止频率的关系，PCP滤波器能有效地分离SSC的主脉冲和Psc。2.修正的Pisarenko方法（MPM）虽然在估计能力上不如最大似然方法（MLM），但它是除MLM之外性能最好的方法之一，而且在计算量上比MLM上级得多。3.低纬度和赤道Psc的波形的形状是一致的当地时间，它是陡峭的中午附近，并有一个更温和的斜率接近午夜。它们具有全球几乎相同的主频率，与Pi 2的主频率一致。这表明Psc的不是腔模振荡，但压缩磁流体（HM）波传播从昼侧到夜侧。4.本文导出了描述磁层-电离层系统中各向异性电磁波与各向异性导电电离层相互作用的自洽电离层边界条件，其形式便于磁层-电离层系统中耦合电磁波的本征模分析。

项目成果

A.Yoshikawa: "Effect of the ionospheric induction current on magnetohydrodynamic waves in the magnetosphere" Proceedings of the NIPR Symposium on Upper Atmosphere Physics(in press). 8. (1995)

A.Yoshikawa：“电离层感应电流对磁层磁流体动力波的影响”NIPR 高层大气物理研讨会论文集（正在出版）。

M.Itonaga et al.: "Global structure of low-latitude and equatorial geo-magnetic pulsations associated with storm sudden com-mencements" submitted to Journal of Ge-omagnetism and Geoelectric-ity.

M.Itonaga 等人：“与风暴突然开始相关的低纬度和赤道地磁脉动的全球结构”提交给《地磁学和地电学杂志》。

M.Itonaga: "Global Structure of Low-Latitude and Equatorial Geomagnetic Pulsations Associated with Storm Sudden Commencements" Journal of Geomagnetism and Geoelectricity. (submitted).

M.Itonaga：“与风暴突然开始相关的低纬度和赤道地磁脉动的全球结构”地磁学和地电杂志。

A,Yoshikawa,M.Itonaga,T.I.Kitamura: "Effect of the ionospheric induction current on magnetohydrodynamic waves in the magnetosphere" Proceedings of the NIPR Symposium on Upper Atmosphere Physics. 8(in press). (1995)

A，Yoshikawa，M.Itonaga，T.I.Kitamura：“电离层感应电流对磁层磁流体动力波的影响”NIPR 高层大气物理研讨会论文集。

糸長雅弘: "区分的3次多項式による非線形フィルタリング" 日本応用数理学会論文誌. (投稿中).

Masahiro Itonaga：“使用分段三次多项式的非线性过滤”日本应用数学学会汇刊（目前正在提交）。