Daytime ionosphere scintillation associated with geomagnetic storms

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.

Download Full-text

The development and validation of a ‘flux-corrected transport’ based solution methodology for the plasmasphere refilling problem following geomagnetic storms

Earth Planets and Space ◽

10.1186/s40623-020-01150-0 ◽

2020 ◽

Vol 72 (1) ◽

Author(s):

K. Chatterjee ◽

R. W. Schunk

Keyword(s):

Geomagnetic Storms ◽

Flux Corrected Transport ◽

Development And Validation ◽

Solution Methodology

Download Full-text

Behavior of foF2 prior to geomagnetic storms according to Slough and Juliusruh data

Advances in Space Research ◽

10.1016/j.asr.2021.02.016 ◽

2021 ◽

Author(s):

A.D. Danilov ◽

A.V. Konstantinova

Keyword(s):

Geomagnetic Storms

Download Full-text

The development of geomagnetic storms after a negative sudden impulse

Planetary and Space Science ◽

10.1016/0032-0633(64)90004-2 ◽

1964 ◽

Vol 12 (6) ◽

pp. 573-578 ◽

Cited By ~ 17

Author(s):

Syun-Ichi Akasofu

Keyword(s):

Geomagnetic Storms ◽

Sudden Impulse

Download Full-text

Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

Annales Geophysicae ◽

10.1007/s00585-996-0608-3 ◽

1996 ◽

Vol 14 (6) ◽

pp. 608-618 ◽

Cited By ~ 189

Author(s):

T. Iyemori ◽

D. R. K. Rao

Keyword(s):

Ring Current ◽

Geomagnetic Storms ◽

Sharp Decrease ◽

Geomagnetic Disturbance ◽

Substorm Onset ◽

Significant Development ◽

H Index ◽

Magnetospheric Tail ◽

Storms And Substorms ◽

Substorm Onsets

Abstract. In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem.

Download Full-text