A quasi-DC current induced into long conductors such as electrical transmission lines or pipe lines. This occurs during geomagnetic storms at the Earth due to the movement of the field lines in the v
icinity of the conductors.
The magnetic fluctuations caused by a geomagnetic storm in Earth's magnetosphere, can cause electric currents to form currents on Earth. These geomagnetically induced currents, or GICs, can overload c
ircuits, tipakers, and in extreme cases destroy transformers.
This system has its Z axis parallel to the Earth's magnetic dipole axis (positive North) and its Y axis is the intersection between the Earth's equator and the geographic meridian 90 degrees east of t
he meridan containing the dipole axis.
The components of the geomagnetic field at the surface of the Earth. These elements are usually denoted thus in the literature:
X-the geographic northward component
Y -the geographic eastward compone
nt
Z-the vertical component, reckoned positive downward
H-the horizontal intensity, of magnitude (X2 + y2 )1/2
F-the total intensity (H2 + Z2 )1/2
I-the inclination (or dip) angle, tan -1 (Z/H)
D-the declination angle, measured from the geographic north direction to the H component direction, positive in an eastward direction.
D = tan-l (Y/X)
However, in NOAA use, the geomagnetic northward and geomagnetic eastward components are called the H and D components. The H axis direction is defined by the mean direction of the horizontal component relative to the geomagnetic north by using the small-angle approximation. Thus the D component = H (the horizontal intensity) multiplied by delta D (the declination angle relative to geomagnetic north, expressed in radians).
The magnetic field in and around the Earth. The intensity of the magnetic field at the Earth’s surface is approximately 32,000 nT at the equator and 62,000 nT at the north pole (the place where a comp
ass needle points vertically downward). The geomagnetic field is dynamic and undergoes continual slow secular changes as well as short-term disturbances (see geomagnetic activity). The geomagnetic field can be approximated by a centered dipole field, with the axis of the dipole inclined to the Earth’s rotational axis by about 11.5 degrees. Geomagnetic dipole north is near geographic coordinate 79 degrees N and 71 degrees W (near Thule, Greenland), and dipole south is near 79 degrees S and 110 degrees E (near Vostok, Antarctica). The observed or dip poles, where the magnetic field is vertical to the Earth’s surface, are near 77 degrees N and 102 degrees W, and 65 degrees S and 139 degrees E. The adopted origin of geomagnetic longitude is the meridian passing through the geomagnetic poles (dipole model) and the geographic south pole. (See also corrected geomagnetic coordinates.)
(1) A worldwide disturbance of the Earth’s magnetic field, distinct from regular diurnal variations. A storm is precisely defined as occurring when the daily Ap index exceeds 29, or (2) NOAA Space We
ather Scale (G) for geomagnetic storm disturbances (see Appendix A).
A geomagnetic storm is a temporary disturbance of the Earths magnetosphere caused by a disturbance in space weather. Associated with solar coronal mass ejections (CME), coronal holes, or solar flares,
a geomagnetic storm is caused by a solar wind shock wave which typically strikes the Earths magnetic field 24 to 36 hours after the event. This only happens if the shock wave travels in a direction toward Earth. The solar wind pressure on the magnetosphere will increase or decrease depending on the Sun's activity. These solar wind pressure changes modify the electric currents in the ionosphere.
One of the most common forms of space weather, a geomagnetic storm refers to any time Earth's magnetic environment, the magnetosphere, undergoes sudden and repeated change. Geomagnetic storms can be c
aused by high-speed blasts of the solar wind and when a CME connects up with the magnetosphere. The sun's magnetic fields peel back the outermost layers of Earth's fields changing the very shape of the magnetosphere. Magnetic storms have measurable effects worldwide, such as radio communication blackouts and power grid failures.
A magnetospheric disturbance typically defined by variations in the horizontal component of the Earth's surface magnetic field. The variation typically starts with a field enhancement associated with
a solar wind pressure pulse and continues with a field depression associated with an enhancement of the diamagnetic magnetospheric ring current. (spase)