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Two‐dimensional observations of midlatitude sporadic E irregularities with a dense GPS array in Japan
Author(s) -
Maeda Jun,
Heki Kosuke
Publication year - 2014
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/2013rs005295
Subject(s) - tec , ionosonde , geology , ionosphere , geodesy , global positioning system , middle latitudes , total electron content , satellite , latitude , electron density , geophysics , physics , astronomy , atmospheric sciences , plasma , telecommunications , computer science , quantum mechanics
We observed two‐dimensional structure and time evolution of ionospheric irregularities caused by midlatitude sporadic E ( E s ) over Japan as positive anomalies of total electron content (TEC) by analyzing the data from the nationwide Global Positioning System (GPS) array. In this paper we report a case study of strong E s observed in the local evening of 21 May 2010, over Tokyo, Japan. In the slant TEC time series, E s showed a characteristic pulse‐like enhancement of ~1.5 TEC units lasting for ~10 min. We plotted these positive TEC anomalies on the subionospheric points of station‐satellite pairs to study the horizontal structure of the E s irregularity. We confirmed that the irregularity existed at the height of ~106 km by comparing the data of multiple GPS satellites, which is consistent with the local ionosonde observations. The horizontal shapes of the E s irregularity showed frontal structures elongated in E‐W, spanning ~150 km in length and ~30 km in width, composed of small patches. The frontal structure appears to consist of at least two parts propagating in different directions: one moved eastward by ~60 m s −1 , and the other moved southwestward by ~80 m s −1 . Similar TEC signatures of E s were detected by other GPS satellites, except one satellite that had line of sight in the N‐S direction which dips by 40–50° toward north, which indicates the direction of plasma transportation responsible for the E s formation. We also present a few additional observation results of strong E s irregularities.