scholarly journals Characteristics of geomagnetic sudden commencement observed in middle and low latitudes

1998 ◽  
Vol 50 (9) ◽  
pp. 755-772 ◽  
Author(s):  
Satoru Tsunomura
Keyword(s):  
Sudden Commencement ◽  
Low Latitudes ◽  
Geomagnetic Sudden Commencement

Automatic Detection of Geomagnetic Sudden Commencement Using Lifting Wavelet Filters

1999 ◽  
pp. 242-251 ◽  
Author(s):  
Shigeru Takano ◽  
Teruya Minamoto ◽  
Hiroki Arimura ◽  
Koichi Niijima ◽  
Toshihiko Iyemori ◽  
...  
Keyword(s):  
Automatic Detection ◽  
Sudden Commencement ◽  
Wavelet Filters ◽  
Lifting Wavelet ◽  
Geomagnetic Sudden Commencement

scholarly journals Penetration of the electric fields of the geomagnetic sudden commencement over the globe as observed with the HF Doppler sounders and magnetometers

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takashi Kikuchi ◽  
Jaroslav Chum ◽  
Ichiro Tomizawa ◽  
Kumiko K. Hashimoto ◽  
Keisuke Hosokawa ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Sudden Commencement ◽  
Ionospheric Currents ◽  
Republic Of China ◽  
F Region ◽  
Electric And Magnetic Fields ◽  
Magnetometer Data ◽  
Electric Potentials ◽  
Geomagnetic Sudden Commencement

AbstractUsing the HF Doppler sounders at middle and low latitudes (Prague, Czech Republic; Tucuman, Argentina; Zhongli, Republic of China, and Sugadaira, Japan), we observed the electric fields of the geomagnetic sudden commencement (SC) propagating near-instantaneously (within 10 s) over the globe. We found that the electric fields of the preliminary impulse (PI) and main impulse (MI) of the SC are in opposite direction to each other and that the PI and MI electric fields are directed from the dusk to dawn and dawn to dusk, respectively, manifesting the nature of the curl-free potential electric field. We further found that the onset and peak of the PI electric field are simultaneous on the day and nightsides (0545, 1250, 1345 MLT) within the resolution of 10 s. With the magnetometer data, we confirmed the near-instantaneous development of the ionospheric currents from high latitudes to the equator and estimated the location of the field-aligned currents that supply the ionospheric currents. The global simultaneity of the electric and magnetic fields does not require the contribution of the magnetohydrodynamic waves in the magnetosphere nor in the F-region ionosphere. The global simultaneity and day–night asymmetry of the electric fields are explained with the ionospheric electric potentials transmitted at the speed of light by the TM0 mode waves in the Earth-ionosphere waveguide.

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