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Altitude development of postmidnight F region field‐aligned irregularities observed using Equatorial Atmosphere Radar in Indonesia
Author(s) -
Dao Tam,
Otsuka Yuichi,
Shiokawa Kazuo,
Tulasi Ram S.,
Yamamoto Mamoru
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl067432
Subject(s) - solstice , earth's magnetic field , altitude (triangle) , ionosphere , atmosphere (unit) , radar , f region , latitude , geology , geodesy , geophysics , meteorology , physics , magnetic field , mathematics , computer science , telecommunications , geometry , quantum mechanics
For the first time, vertical rise velocities of postmidnight field‐aligned irregularities (FAIs) at low geomagnetic latitudes have been examined near the June solstice by using two‐dimensional maps of F region FAI echoes observed with the Equatorial Atmosphere Radar in Indonesia for 3 years starting in May 2010. We found 15 freshly growing FAIs at postmidnight between May and August during the 3 years. The rise velocities of FAIs are smaller at postmidnight than at postsunset, and most postmidnight FAIs do not exceed an altitude of 450 km. Based on the rise velocities, a lower limit for the creation time of the postmidnight FAIs is estimated to be between 21:30 LT and 02:00 LT for 14 of the 15 events, indicating that this class of FAIs is distinct from the postsunset FAIs.