NationMaster - Encyclopedia: Geomagnetic storm

A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere. 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 Earth's 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. Magnetic storms usually last 24 to 48 hours, but some may last for many days. Schematic of Earths magnetosphere. ... A composite image showing two CMEs (at 2 oclock and 8 oclock), with the sun at center. ... The corona is the luminous plasma atmosphere of the Sun extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ... A Solar Flare, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to tens of millions of hydrogen bombs. ... The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ... The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ... Relationship of the atmosphere and ionosphere The ionosphere is the part of the atmosphere that is ionized by solar radiation. ...

Solar particles interact with Earth's magnetosphere

1 Interactions with planetary processes
2 Geomagnetic storm effects
3 Internal links
4 External links
5 Suggested reading
6 See also

Image File history File links Download high resolution version (1200x656, 391 KB)Artists rendition of Earths magnetosphere. ... Image File history File links Download high resolution version (1200x656, 391 KB)Artists rendition of Earths magnetosphere. ... Schematic of Earths magnetosphere. ...

Interactions with planetary processes

The solar wind also carries with it the magnetic field of the Sun. This field will have either a North or South orientation. If the solar wind has energetic bursts, contracting and expanding the magnetosphere, or if the solar wind takes a southward polarization, geomagnetic storms can be expected. The southward field causes magnetic reconnection of the dayside magnetopause, rapidly injecting magnetic and particle energy into the Earth's magnetosphere. In electrodynamics, polarization (also spelled polarisation) is a property of waves, such as light and other electromagnetic radiation. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ...

During a geomagnetic storm, the ionosphere's F₂ layer will become unstable, fragment, and may even disappear. In the Northern and Southern pole regions of the Earth, aurora will be observable in the sky. The F region is the portion of the ionosphere existing between approximately 160 and 400 km above the surface of the Earth, consisting of layers of increased free-electron density caused by the ionizing effect of solar radiation. ... Aurora borealis Polar aurorae are optical phenomena characterized by colorful displays of light in the night sky. ...

Magnetosphere in the near-Earth space environment.

Image File history File links A schematic diagram depicting the magnetosphere in the near-Earth space environment. ...

Geomagnetic storm effects

Radiation hazards to humans

Intense solar flares release very-high-energy particles that can be as injurious to humans as the low-energy radiation from nuclear blasts. Earth's atmosphere and magnetosphere allow adequate protection for us on the ground, but astronauts in space are subject to potentially lethal dosages of radiation. The penetration of high-energy particles into living cells can cause chromosome damage, cancer, and a host of other health problems. Large doses can be fatal immediately. Solar protons with energies greater than 30 MeV are particularly hazardous. In October 1989, the Sun produced enough energetic particles that an astronaut on the Moon, wearing only a space suit and caught out in the brunt of the storm, would probably have died; the expected dose would be about 7000 rem. (Astronauts who had time to gain safety in a shelter beneath moon soil would have absorbed only slight amounts of radiation.) The astronauts on the Mir station were subjected to daily doses of about twice the yearly dose on the ground, and during the solar storm at the end of 1989 they absorbed their full-year radiation dose limit in just a few hours. A Solar Flare, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to tens of millions of hydrogen bombs. ... Nuclear Blast is an independent record label and mail order record distributor with subsidiaries in Germany, the United States and Brazil. ... Layers of Atmosphere (NOAA) Air redirects here. ... Schematic of Earths magnetosphere. ... U.S. Space Shuttle astronaut Bruce McCandless II using a manned maneuvering unit (MMU) outside the Challenger in 1984. ... Ionizing radiation is either particle radiation or electromagnetic radiation in which an individual particle/photon carries enough energy to ionize an atom or molecule by completely removing an electron from its orbit. ... Figure 1: Chromosome. ... When normal cells are damaged beyond repair, they are eliminated by apoptosis. ... Properties In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... 1989 (MCMLXXXIX) was a common year starting on Sunday of the Gregorian calendar. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... Apollo 15 space suit A spacesuit is a complex system of garments, equipment, and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space. ... The Röntgen equivalent man or rem (symbol rem) is an obsolete unit of radiation dose. ... Meanings of MIR: Mail-in rebate Medical Inspection Room - the place for sick parade in most British and Commonwealth militaries and many NGOs. ...

Solar proton events can also produce elevated radiation aboard aircraft flying at high altitudes. Although these risks are small, monitoring of solar proton events by satellite instrumentation allows the occasional exposure to be monitored and evaluated, and eventually the flight paths and altitudes adjusted in order to lower the absorbed dose of the flight crews. A Solar Proton Event occurs when high-energy protons, ejected from the suns surface during a solar flare, get caught by the Earths magnetic field and cause ionization in the ionosphere. ... A jetliner is an airliner powered by jet engines (usually of the turbofan type). ... Aircrew members may include pilots, flight attendants, flight engineers, navigators, Taccos, signallers, observers, (air) gunners, weapons specialists, loadmasters and various electronics system operators depending on the age during which the aircraft operated and the type of operations. ...

Climate

The Sun is the heat engine that drives the circulation of our atmosphere. Although it has long been assumed to be a constant source of energy, recent measurements of this solar constant have shown that the base output of the Sun can vary by up to two tenths of a percent over the 11-year solar cycle. Temporary decreases of up to one-half percent have been observed. Atmospheric scientists say that this variation is significant and that it can modify climate over time. Plant growth has been shown to vary over the 11-year sunspot and 22-year magnetic cycles of the Sun, as evidenced in tree-ring records. Solar irradiance spectrum at top of atmosphere. ... It has been suggested that this article or section be merged with Schwabe-Wolf cycle. ... A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ...

While the solar cycle has been nearly regular during the last 300 years, there was a period of 70 years during the 17th and 18th centuries when very few sunspots were seen (even though telescopes were widely used). This drop in sunspot number coincided with the timing of the Little Ice Age in Europe, implying a Sun-to-climate connection. Recently, a more direct link between climate and solar variability has been speculated. Stratospheric winds near the equator blow in different directions, depending on the time in the solar cycle. Studies are under way to determine how this wind reversal affects global circulation patterns and weather. The Little Ice Age (LIA) was a period of cooling lasting approximately from the 14th to the mid-19th centuries, although there is no generally agreed start or end date: some confine the period to 1550-1850. ... World map showing Europe Political map Europe is one of the seven continents of Earth which, in this case, is more a cultural and political distinction than a physiographic one, leading to various perspectives about Europes borders. ...

During proton events, many more energetic particles reach Earth's middle atmosphere. There they cause molecular ionization, creating chemicals that destroy atmospheric ozone and allow increased amounts of harmful solar ultraviolet radiation to reach Earth's surface. A solar proton event in 1982 resulted in a temporary 70% decrease in ozone densities. For other uses, see Ozone (disambiguation). ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Properties In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ...

Biology

There is a growing body of evidence that changes in the geomagnetic field affect biological systems. Studies indicate that physically stressed human biological systems may respond to fluctuations in the geomagnetic field. Interest and concern in this subject have led the Union of Radio Science International to create a new commission entitled Electromagnetics in Biology and Medicine.

Possibly the most closely studied of the variable Sun's biological effects has been the degradation of homing pigeons' navigational abilities during geomagnetic storms. Pigeons and other migratory animals, such as dolphins and whales, have internal biological compasses composed of the mineral magnetite wrapped in bundles of nerve cells. While this probably is not their primary method of navigation, there have been many pigeon race smashes, a term used when only a small percentage of birds return home from a release site. Because these losses have occurred during geomagnetic storms, pigeon handlers have learned to ask for geomagnetic alerts and warnings as an aid to scheduling races. The homing pigeon is a variety of domesticated Rock Dove (Columba livia) that has been selectively bred to be able to find its way home over extremely long distances. ... Genera For other uses, see Dolphin (disambiguation). ... Whales are the largest species of exclusively aquatic mammals, members of the order Cetacea, which also includes dolphins and porpoises. ... // Headline text Magnetite is a ferrimagnetic mineral form of iron(II,III) oxide, with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. ...

Disrupted systems

Communications

Many communication systems use the ionosphere to reflect radio signals over long distances. Ionospheric storms can affect radio communication at all latitudes. Some radio frequencies are absorbed and others are reflected, leading to rapidly fluctuating signals and unexpected propagation paths. TV and commercial radio stations are little affected by solar activity, but ground-to-air, ship-to-shore, Voice of America, Radio Free Europe, and amateur radio are frequently disrupted. Radio operators using high frequencies rely upon solar and geomagnetic alerts to keep their communication circuits up and running. Radio propagation is a term used to explain how radio waves behave when they are transmitted, or are propagated from one point on the Earth to another. ... The Voice of America (VOA) is the official international broadcasting service of the Government of the United States. ... Radio Free Europe/Radio Liberty (RFE/RL) is a radio and communications organization which is funded by the United States Congress. ... Amateur radio, often called ham radio, is a hobby enjoyed by about 3 million people[1] throughout the world. ...

Some military detection or early warning systems are also affected by solar activity. The over-the-horizon radar bounces signals off the ionosphere in order to monitor the launch of aircraft and missiles from long distances. During geomagnetic storms, this system can be severely hampered by radio clutter. Some submarine detection systems use the magnetic signatures of submarines as one input to their locating schemes. Geomagnetic storms can mask and distort these signals. Over-The-Horizon radar (OTHR) is a design concept for radar system to overcome the problem that radio waves (a form of light) travel in a straight line, making over the horizon detection difficult. ...

The Federal Aviation Administration routinely receives alerts of solar radio bursts so that they can recognize communication problems and forego unnecessary maintenance. When an aircraft and a ground station are aligned with the Sun, jamming of air-control radio frequencies can occur. This can also happen when an Earth station, a satellite, and the Sun are in alignment. The Federal Aviation Administration is the entity of the United States government which regulates and oversees all aspects of civil aviation in the U.S. // Activities Along with the European Joint Aviation Authorities, the FAA is one of the two main agencies worldwide responsible for the certification of new aircraft. ...

The telegraph lines in the past were affected by geomagnetic storms as well. The telegraphs used a long wire for the data line, stretching for many miles, using ground as the return wire and being fed with DC power from a battery; this made them (together with the power lines mentioned below) susceptible to being influenced by the fluctuations caused by the ring current. The voltage/current induced by the geomagnetic storm could have led to diminishing of the signal, when subtracted from the battery polarity, or to overly strong and spurious signals when added to it; some operators in such cases even learned to disconnect the battery and rely on the induced current as their power source. In extreme cases the induced current was so high the coils at the receiving side burst in flames, or the operators received electric shocks. Geomagnetic storms affect also long-haul telephone lines, including undersea cables.[1] It has been suggested that this article or section be merged into Telegraphy. ... A ring current is an electric current carried by charged particles trapped in a planets magnetosphere. ...

Navigation systems

Systems such as GPS, LORAN, and OMEGA are adversely affected when solar activity disrupts their signal propagation. The OMEGA system consists of eight transmitters located throughout the world. Airplanes and ships use the very low frequency signals from these transmitters to determine their positions. During solar events and geomagnetic storms, the system can give navigators information that is inaccurate by as much as several miles. If navigators are alerted that a proton event or geomagnetic storm is in progress, they can switch to a backup system. Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... LORAN (LOng RAnge Navigation) is a terrestrial navigation system using low frequency radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. ... Omega is the name for the first truly global radionavigation system for aircraft operated by the United States of America in cooperation with six partner nations. ...

GPS signals are affected when solar activity causes sudden variations in the density of the ionosphere, causing the GPS signals to scintillate. The scintillation of satellite signals during ionospheric disturbances is studied at HAARP during ionospheric modification experiments. It has also been studied at the National Science Foundation equatorial ionospheric observation facility in Jicamarca, Peru. Aerial view of the HAARP site, looking towards Mt. ... The logo of the National Science Foundation The National Science Foundation (NSF) is an independent United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. ...

Satellites

Geomagnetic storms and increased solar ultraviolet emission heat Earth's upper atmosphere, causing it to expand. The heated air rises, and the density at the orbit of satellites up to about 1000 km increases significantly. This results in increased drag on satellites in space, causing them to slow and change orbit slightly. Unless Low Earth Orbit satellites are routinely boosted to higher orbits, they slowly fall, and eventually burn up in Earth's atmosphere. Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. ... A satellite is any object that orbits another object (which is known as its primary). ... An object falling through a gas or liquid experiences a force in direction opposite to its motion. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ...

Skylab is an example of a spacecraft reentering Earth's atmosphere prematurely as a result of higher-than-expected solar activity. During the great geomagnetic storm of March 1989, four of the Navy's navigational satellites had to be taken out of service for up to a week, the U.S. Space Command had to post new orbital elements for over 1000 objects affected, and the Solar Maximum Mission satellite was sent towards meeting the Skylab fate in December the same year. Drawing of Skylab with components labelled Skylab was the first space station the United States launched into orbit. ... Atmospheric entry is the transition from the vacuum of space to the atmosphere of any planet or other celestial body. ... 20 years of solar irradiance data from satellites Solar variation refers to fluctuation in the amount of energy emitted by the Sun. ... U.S. Air Force Space Command The United States Air Force Space Command (USAFSPC or AFSPC) is a major command of the U.S. Air Force with headquarters at Peterson Air Force Base, Colorado. ... The elements of an orbit are the parameters needed to specify that orbit uniquely, given a model of two ideal masses obeying the Newtonian laws of motion and the inverse-square law of gravitational attraction. ... The Solar Maximum Mission satellite (or SolarMax) was designed to investigate solar phenomenon, particularly solar flares. ...

The vulnerability of the satellites depends on their position as well. The South Atlantic Anomaly is a perilous place for a satellite to pass through. The Van Allen radiation belts and the point of the South Atlantic Anomaly. ...

As technology has allowed spacecraft components to become smaller, their miniaturized systems have become increasingly vulnerable to the more energetic solar particles. These particles can cause physical damage to microchips and can change software commands in satellite-borne computers. The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ... Microelectronics designed for environments with high levels of ionizing radiation have special design challenges. ...

Differential charging

Another problem for satellite operators is differential charging. During geomagnetic storms, the number and energy of electrons and ions increase. When a satellite travels through this energized environment, the charged particles striking the spacecraft cause different portions of the spacecraft to be differentially charged. Eventually, electrical discharges can arc across spacecraft components, harming and possibly disabling them. Properties The electron is a lightweight fundamental subatomic particle that carries a negative electric charge. ... // An ion is an atom or a group of atoms (a chemical substance), or subatomic particle, with a net electric charge. ... In physics, a charged particle is a particle with an electric charge. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ... An electric arc can melt calcium oxide. ...

Bulk charging

Bulk charging (also called deep charging) occurs when energetic particles, primarily electrons, penetrate the outer covering of a satellite and deposit their charge in its internal parts. If sufficient charge accumulates in any one component, it may attempt to neutralize by discharging to other components. This discharge is potentially hazardous to the satellite's electronic systems.

Geologic exploration

Earth's magnetic field is used by geologists to determine subterranean rock structures. For the most part, these geodetic surveyors are searching for oil, gas, or mineral deposits. They can accomplish this only when Earth's field is quiet, so that true magnetic signatures can be detected. Other surveyors prefer to work during geomagnetic storms, when the variations to Earth's normal subsurface electric currents help them to see subsurface oil or mineral structures. For these reasons, many surveyors use geomagnetic alerts and predictions to schedule their mapping activities.

Electric power

When magnetic fields move about in the vicinity of a conductor such as a wire, an electric current is induced into the conductor. This happens on a grand scale during geomagnetic storms (the same mechanism also influences telephone and telegraph lines, see above). Power companies transmit alternating current to their customers via long transmission lines. The nearly direct currents induced in these lines from geomagnetic storms are harmful to electrical transmission equipment, especially to the transformers—it overheats their coils and causes saturation of their cores, constraining their performance; it also tends to trip various protective devices. On March 13, 1989, in Québec, 6 million people were without commercial electric power for 9 hours as a result of a huge geomagnetic storm. Some areas in the northeastern U.S. and in Sweden also lost power. By receiving geomagnetic storm alerts and warnings, power companies can minimize damage and power outages. Current flowing through a wire produces a magnetic field (B, labeled M here) around the wire. ... Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux. ... Three-phase pole-mounted step-down transformer. ... For magnetic materials, saturation is the state when the material can not absorb a stronger magnetic field, such that an increase of magnetization produces no significant change in magnetic flux density. ... March 13 is the 72nd day of the year in the Gregorian calendar (73rd in leap years). ... 1989 (MCMLXXXIX) was a common year starting on Sunday of the Gregorian calendar. ... For the capital, see Quebec City. ...

Pipelines

Rapidly fluctuating geomagnetic fields can induce currents into pipelines. During these times, several problems can arise for pipeline engineers. Flow meters in the pipeline can transmit erroneous flow information, and the corrosion rate of the pipeline is dramatically increased. If engineers unwittingly attempt to balance the current during a geomagnetic storm, corrosion rates may increase even more. Pipeline managers routinely receive alerts and warnings to help them provide an efficient and long-lived system. Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux. ... Rust, the most familiar example of corrosion. ...

Internal links

A New Theory of Magnetic Storms

A New Theory of Magnetic Storms is a 1931 book by Chapman and Ferraro which sought to explain the phenomenon of geomagnetic storms. ...

External links

Geomagnetic Storms Can Threaten Electric Power Grid - American Geophysical Union, Earth in Space, Vol. 9, No. 7, March 1997, pp. 9-11.
The warp and woof of a geomagnetic storm - NASA's Space Science News.
NOAA Space Weather Scales - NOAA.

Aurora Watch, at the university of Lancshire, gives email warnings of coronal mass ejections and geomagnetic storms for aurora watching enthusiasts: The American Geophysical Union (or AGU) is a nonprofit organization of geophysicists, consisting (as of 2004) of over 41,000 members from 130 countries. ... This article or section does not cite its references or sources. ... Space science, or the space sciences, are fields of science that are concerned with the study or utilization of outer space. ... The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency of the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. ...

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