scholarly journals On the Occurrence of Geomagnetic Storms with Sudden Commencements.

1996 ◽  
Vol 48 (7) ◽  
pp. 1011-1016 ◽  
Author(s):  
V. M. Silrergleit
Keyword(s):  
Geomagnetic Storms ◽  
Sudden Commencements

scholarly journals Measurement of geomagnetically induced current (GIC) around Tokyo, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Shinichi Watari ◽  
Satoko Nakamura ◽  
Yusuke Ebihara
Keyword(s):  
Solar Flare ◽  
Geomagnetic Storms ◽  
Power Grids ◽  
Geomagnetic Variation ◽  
Induced Current ◽  
Interplanetary Shocks ◽  
Geomagnetic Disturbances ◽  
Geomagnetically Induced Current ◽  
Middle Latitudes ◽  
Sudden Commencements

AbstractWe need a typical method of directly measuring geomagnetically induced current (GIC) to compare data for estimating a potential risk of power grids caused by GIC. Here, we overview GIC measurement systems that have appeared in published papers, note necessary requirements, report on our equipment, and show several examples of our measurements in substations around Tokyo, Japan. Although they are located at middle latitudes, GICs associated with various geomagnetic disturbances are observed, such as storm sudden commencements (SSCs) or sudden impulses (SIs) caused by interplanetary shocks, geomagnetic storms including a storm caused by abrupt southward turning of strong interplanetary magnetic field (IMF) associated with a magnetic cloud, bay disturbances caused by high-latitude aurora activities, and geomagnetic variation caused by a solar flare called the solar flare effect (SFE). All these results suggest that GIC at middle latitudes is sensitive to the magnetospheric current (the magnetopause current, the ring current, and the field-aligned current) and also the ionospheric current.

scholarly journals A Method for Recognition of Sudden Commencements of Geomagnetic Storms Using Digital Differentiating Filters

2022 ◽  
Vol 12 (1) ◽  
pp. 413
Author(s):  
Victor Getmanov ◽  
Roman Sidorov ◽  
Alexei Gvishiani
Keyword(s):  
Decision Making ◽  
False Recognition ◽  
Geomagnetic Field ◽  
Geomagnetic Storms ◽  
Maximum Amplitude ◽  
Sudden Commencement ◽  
Magnetic Components ◽  
Observatory Data ◽  
Sudden Commencements ◽  
Decision Making Rule

This article describes a method for recognizing sudden commencement events using digital differentiating filters. This method is applied to INTERMAGNET observatory data. Maximum amplitude derivatives for the magnetic components (X, Y, Z) and the total intensity (F) of the geomagnetic field are introduced, and the decision-making rule is formulated. The authors developed a procedure for selecting optimal digital differentiating filters. Estimates of probabilities of correct and false recognition of sudden commencements were obtained. The calculations of the probabilistic characteristics have confirmed the effectiveness of the method.

scholarly journals Seasonal variations in the occurrence of geomagnetic storms

1996 ◽  
Vol 14 (3) ◽  
pp. 286-289 ◽  
Author(s):  
John R. Taylor ◽  
Mark Lester ◽  
Timothy K. Yeoman
Keyword(s):  
Solar Wind ◽  
Seasonal Variations ◽  
Annual Variation ◽  
Geomagnetic Storms ◽  
Magnetic Activity ◽  
Magnetic Storms ◽  
Sudden Commencement ◽  
Sudden Commencements ◽  
Solar Wind Origin

Abstract. Seasonal variations in the onset of magnetic storms are investigated. For the purposes of this study storms have been defined as events in which Dst falls below –50 nT for at least four consecutive hours. The storms have been classified as either storm sudden commencements (SSCs; storms initiated by a sudden commencement) or as storm gradual commencements (SGCs; all other storms). It is found that the semi-annual variation of magnetic activity is reflected in the occurrence statistics of SGC events only, indicative that the solar wind origin is different for SSCs and SGCs. It is suggested that the heliospheric latitude model of seasonal magnetic activity is relatively ineffective in modulating the previously observed seasonal variations in the occurrence of magnetic storms.

scholarly journals Sudden Commencements of Geomagnetic Storms and Their Local Irregularities

1965 ◽  
Vol 17 (1) ◽  
pp. 69-93 ◽  
Author(s):  
Rikio MAEDA ◽  
Tsuneji RIKITAKE ◽  
Takesi NAGATA
Keyword(s):  
Geomagnetic Storms ◽  
Sudden Commencements

Disappearing Solar Filaments and Interplanetary Shock Waves

1983 ◽  
Vol 5 (2) ◽  
pp. 202-204 ◽  
Author(s):  
C. S. Wright
Keyword(s):  
Geomagnetic Storms ◽  
Close Association ◽  
Interplanetary Shock ◽  
Sudden Commencement ◽  
The Sun ◽  
Type Ii ◽  
Type Iv ◽  
Magnetohydrodynamic Shock ◽  
Solar Filaments ◽  
Sudden Commencements

The close association between flare events having metric radio type II and type IV bursts and the subsequent occurrence of sudden commencement geomagnetic storms is well known. In such cases it has been amply demonstrated (e.g. Malitson et al. 1973; Cane et al. 1982) that the sudden commencement (SC) is caused by the same magnetohydrodynamic shock which originates near the Sun and which produces the type II burst. Recently, a study of geomagnetic storms thought to be associated with the disappearance of filaments from quiet regions of the Sun (Joselyn and McIntosh 1981) showed that several of these storms began with marked sudden commencements.

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