[P-EM12] 太陽地球系結合過程の研究基盤形成

[PEM12-03] Sounding of E-F coupling over Japan by using ground-based GNSS TEC with a double-thin-shell approach

*傅 維正¹、横山 竜宏¹、セサンガ ニコラス²、山本 衛¹ (1.京都大学生存圏研究所、2.オスロ大学)

キーワード：電離圏、衛星測位システム、全電子数、ダブルシェルモデル

Irregularities in the ionospheric E and F regions are frequently coupled in the nighttime mid-latitude ionosphere, observationally and theoretically. In this paper, total electron content (TEC) measurements from a dense ground-based Global Navigation Satellite System (GNSS) array with more than 1200 receivers are used to investigate the E-F coupling phenomenon over Japan by taking a double-thin-shell approach. We assumed that the TEC perturbations (TECPs) mainly concentrate in E and F regions; two thin shells parameterize the three-dimensional (3-D) ionosphere; perturbation components are identical at any point within a given grid block of each layer. Validation shows that the irregularities in E and F regions can be reconstructed simultaneously by this newly-developed technique. In this paper, we investigated two event days of nighttime medium-scale traveling ionospheric disturbances (MSTIDs). The coexistence of northwest-southeast (NW-SE) aligned irregular structures in both E and F regions was observed with ground-based GNSS TEC for the first time. The reconstruction results show that the E- and F-region irregularities share similar propagation parameters, which are clear evidence that they are strongly coupled with each other.