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Observation of Synchronization Between Instabilities of the Sporadic E Layer and Geomagnetic Field Line Connected F Region Medium‐Scale Traveling Ionospheric Disturbances
Author(s) -
Ejiri Mitsumu K.,
Nakamura Takuji,
Tsuda Takuo T.,
Nishiyama Takanori,
Abo Makoto,
She ChiaoYao,
Nishioka Michi,
Saito Akinori,
Takahashi Toru,
Tsuno Katsuhiko,
Kawahara Takuya D.,
Ogawa Takayo,
Wada Satoshi
Publication year - 2019
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja026242
Subject(s) - ionosonde , ionosphere , sporadic e propagation , earth's magnetic field , field line , physics , f region , electron density , geophysics , scale height , atmospheric sciences , geology , plasma , astrophysics , magnetic field , quantum mechanics
A frequency‐tunable resonance scattering lidar with high temporal/vertical resolutions (1 min/15 m) observed sporadic calcium ion (Ca + s ) layers at ~100 km over Tachikawa (geographical/geomagnetic latitude: 35.7°N/27.1°N), Japan, on 21–22 August 2014. Simultaneously, sporadic E ( E s ) parameters and medium‐scale traveling ionospheric disturbances (MSTIDs) were observed by an ionosonde and Global Navigation Satellite System receiver network, GEONET, respectively. The maximum densities of the Ca + and electrons in the E s layer had a strong positive correlation. As observation started ~23:30 LT, the Ca + s layer and the associated E s layer descended at ~2.8 km/hr with density irregularities including Kelvin‐Helmholtz billow‐like structures suggesting the presence of background neutral wind shear and instability. And the total electron content variations showed large amplitude associated with the MSTIDs at an altitude of 300 km in synchronization with the Ca + column abundance surges at 100 km over Tachikawa; in their respective E and F region locations connected by geomagnetic field line these irregularities are found to vary in phase. At ~02:00 LT, the Ca + s layer stopped descending at ~100 km due to larger ion‐neutral collision frequency in the lower altitudes and resided there quietly until sunrise; both Ca + column abundance enhancements and the large total electron content variation disappeared as the descent of the Ca + s layer stopped, implicating that the MSTID structure cannot be sustained without the density irregularities of the E s layer. This is the first synchronous observation of the coupling between the E s density irregularities and the MSTIDs in the F region along a common magnetic flux tube.