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Variation of the Equatorial Height Anomaly During the Main Phase of 2015 St. Patrick's Day Geomagnetic Storm Using ANNIM and TIEGCM
Author(s) -
Sai Gowtam V.,
Lei Jiuhou,
Tulasi Ram S.,
Luan Xiaoli,
Ren Dexin,
Zhong Jiahao
Publication year - 2019
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja026703
Subject(s) - geomagnetic storm , ionosphere , anomaly (physics) , storm , earth's magnetic field , atmospheric sciences , thermosphere , geology , universal time , climatology , geophysics , meteorology , physics , magnetic field , astronomy , quantum mechanics , condensed matter physics
A double‐peak structure in the peak height of ionospheric F 2 layer around ±10 o geomagnetic latitudes similar to the equatorial ionization anomaly was recently reported. This unique feature was referred as the equatorial height anomaly (EHA). In the present paper, a simulation study is carried out using the data‐driven artificial neural network‐based two‐dimensional ionospheric model (ANNIM‐2D) and the physics‐based thermosphere‐ionosphere‐electrodynamics general circulation model (TIEGCM) to understand the local time and latitudinal variation of EHA during the main phase of St. Patrick's Day geomagnetic storm. Both the ANNIM‐2D and TIEGCM consistently show pronounced EHA during the main phase of the geomagnetic storm. Further, the local time of EHA development on the storm day is much earlier (nearly 2 hr) than the quiet time over Brazilian sector (90°W). The TIEGCM simulation revealed that the storm time enhancement of the equatorial fountain associated with the enhanced equatorial zonal electric field is the main controlling factor for the pronounced EHA during the main phase. The storm time meridional neutral winds positively contribute to the development of EHA. This study revealed the direct manifestation of the storm time‐enhanced plasma fountain on the EHA.