日本地球惑星科学連合2018年大会

講演情報

[EE] 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] Space Weather, Space Climate, and VarSITI

2018年5月24日(木) 10:45 〜 12:15 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:片岡 龍峰(国立極地研究所)、Antti A Pulkkinen (NASA Goddard Space Flight Center)、草野 完也(名古屋大学宇宙地球環境研究所、共同)、塩川 和夫(名古屋大学宇宙地球環境研究所)

[PEM12-P21] Experimental evidence on the dependence of the standard GPS phase scintillation index on the ionospheric plasma drift around noon sector of the polar ionosphere

Yong WANG1、*Qing-He Zhang1P. T. Jayachandran2J. I. Moen3Zan-Yang Xing1R. Chadwick2Yu-Zhang Ma1 J. M. Ruohoniemi4M. Lester5 (1.Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, China、2.Physics Department, University of New Brunswick, Fredericton, New Brunswick, Canada、3.Department of Physics, University of Oslo, Oslo, Norway、4.Bradley Department of Electrical and Computer Engineering, Virginia Tech., Blacksburg, Virginia, USA、5.Department of Physics and Astronomy, University of Leicester, Leicester, UK)

キーワード:Polar ionosphere, Ionospheric scintillation, Standard scintillation indices, Plasma drift velocity, Fresnel frequency, GNSS

First ever experimental proof of a clear and strong dependence of the standard phase scintillation index (σφ) derived using Global Positioning System (GPS) measurements on the ionospheric plasma flow around the noon sector of polar ionosphere is presented. σφ shows a strong linear dependence on the plasma drift speed measured by the SuperDARN radars whereas the amplitude scintillation index (S4) does not. This observed dependence can be explained as a consequence of Fresnel frequency dependence of the relative drift and the used constant cut-off frequency (0.1 Hz) to detrend the data for obtaining standard σφ. The lack of dependence of S4 on the drift speed possibly eliminates the plasma instability mechanism(s) involved as a cause of the dependence. These observations further confirm that the standard phase scintillation index is much more sensitive to plasma flow, therefore, utmost care must be taken when identifying phase scintillation (diffractive phase variations) from refractive (deterministic) phase variations, especially in the polar region where the ionospheric plasma drift is much larger than in equatorial and mid-latitude regions.