Frequently Asked Questions
Here you may find answers to common questions related to the EURISGIC project.
During a geomagnetic storm electrojets are generated in the ionosphere, at an altitude of about 100 km, reaching up to several million Amperes. When these currents change in time geoelectric fields are, according to Faraday’s law of induction, induced at the surface of the Earth and in the ground.
A geomagnetic storm is a global disturbance in the Earth’s magnetic field lasting from a few hours to a few days. The source of a geomagnetic storm is the arrival of a high-speed solar wind from a coronal hole or a Coronal Mass Ejection (CME) originating from active regions on the Sun. The most intense geomagnetic storms are usually produced by fast CMEs, which reach Earth within a day. Geomagnetic storms are more frequent during the solar maximum and during the declining phase but can, in principle, occur at any time during the solar cycle.
The geoelectric fields drive currents in the ground and in man-made conductor networks, such as power grids, communication cables, oil and gas pipelines and railway equipment. A common name for these currents is geomagnetically induced currents (GIC) and they are the ground end of the space weather chain. GIC may cause problems, such as increased corrosion of pipeline steel and damage high-voltage power transformers and disturb protective relays. GIC may also affect geophysical exploration surveys and oil and gas drilling operations.
A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere caused by a disturbance in theinterplanetary medium. A geomagnetic storm is a major component of space weather and provides the input for many other components of space weather. A geomagnetic storm is caused by a solar wind shock wave and/or cloud of magnetic field which interacts with the Earth's magnetic field. The increase in the solar wind pressure initially compresses the magnetosphere and the solar wind magnetic field will interact with the Earth’s magnetic field and transfer an increased amount of energy into the magnetosphere. Both interactions cause an increase in movement of plasma through the magnetosphere (driven by increased electric fields inside the magnetosphere) and an increase in electric current in the magnetosphere and ionosphere. During the main phase of a geomagnetic storm, electric current in the magnetosphere create magnetic force which pushes out the boundary between the magnetosphere and the solar wind. The disturbance in the interplanetary medium which drives the geomagnetic storm may be due to a solar coronal mass ejection (CME) or a high speed stream (co-rotating interaction region or CIR) of the solar wind originating from a region of weak magnetic field on the Sun’s surface. The frequency of geomagnetic storms increases and decreases with the sunspot cycle. CME driven storms are more common during the maximum of the solar cycle and CIR driven storms are more common during the minimum of the solar cycle.
What is Space weather?