日本地球惑星科学連合2022年大会

講演情報

[E] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM12] 太陽地球系結合過程の研究基盤形成

2022年6月3日(金) 11:00 〜 13:00 オンラインポスターZoom会場 (5) (Ch.05)

コンビーナ:山本 衛(京都大学生存圏研究所)、コンビーナ:小川 泰信(国立極地研究所)、野澤 悟徳(名古屋大学宇宙地球環境研究所)、コンビーナ:吉川 顕正(九州大学大学院理学研究院地球惑星科学部門)、座長:山本 衛(京都大学生存圏研究所)、小川 泰信(国立極地研究所)、野澤 悟徳(名古屋大学宇宙地球環境研究所)、吉川 顕正(九州大学大学院理学研究院地球惑星科学部門)

11:00 〜 13:00

[PEM12-P03] Automatic derivation of ionospheric electron density profile by VIPIR2 ionosonde observation and its validation

*西岡 未知1、前野 英生1、山川 浩幸1斎藤 享2津川 卓也1 (1.(独)情報通信研究機構、2.国立研究開発法人 海上・港湾・航空技術研究所 電子航法研究所)

キーワード:イオノゾンデ、電子密度高度分布、機械学習

An ionosonde transmits high-frequency radio waves towards the ionosphere while sweeping frequencies and measures delay time until the transmitted radio waves are reflected to the ionosonde by the ionosphere. Normally, the observation data is recorded as “ionogram” in which the signal strength is indicated with the horizontal axis of the frequency and the vertical axis of virtual height. The virtual height is derived by multiplying the speed of light by flight time and dividing by two. The virtual height is different from true height since the propagation speed of the transmission radio wave is a function of the electron density distribution and the geomagnetic field. In order to obtain the electron density distribution with respect to the “true height” from the ionogram, a procedure is required in which an echo trace is performed to read the frequency and delay time of the reflected echo one by one, and the propagation speed is considered and converted to the electron density with respect to the true height.

National Institute of Information and Communications Technology has been conducting routine ionosonde observations for many years. In this project, some parameters such as critical frequencies and virtual heights of the E- and F- layers are automatically derived, however, the echo trace has not been conducted yet. Recently, we developed a technique to trace ionospheric echoes using machine learning. The traced echoes were subjected to a procedure of deriving electron density profile against true height using the POLynominal Analysis program (POLAN). In this presentation, we will overview our derivation technique of ionospheric electron density profile. We also show some results of its validation using density profile data observed with an incoherent scatter radar and LEO satellite occultation data.