Geomagnetic storms, induced by solar activity, pose significant hazards to satellites, electrical power distribution systems, radio communications, navigation, and geophysical surveys. Strong storms can expose astronauts and crews of high-flying aircraft to dangerous levels of radiation. Economic losses from recent geomagnetic storms have run into hundreds of millions of dollars. With the U.S. Geological Survey (USGS) as the lead agency, an international network of geomagnetic observatories monitors the onset of solar-induced storms and gives warnings that help diminish losses to military and commercial operations and facilities.

Geomagnetic Storms

In January 1997, a geomagnetic storm severely damaged the U.S. Telstar 401 communication satellite, which was valued at $200 million, and left it inoperable. A geomagnetic storm in 1994 damaged two Canadian communication satellites, which were replaced at a cost of about $400 million. A geomagnetic storm in 1989 "blacked out" the power distribution system for Quebec, Canada, and left 6 million people without electricity for 9 hours at a cost of $300 million. Although these events and their specific impacts were not predicted, current technology promises to provide real-time warnings and measures to contend with solar-induced storms.

Our society is depending more and more upon advanced technological systems that can be adversely affected by solar storms. Space vehicles and high-altitude aircraft rely on such systems for life safety and navigation. Global communications depend upon systems using high-frequency (HF), very high frequency (VHF), and ultra high frequency (UHF) radio signals. Electrical power distribution worldwide relies upon vast, interconnected systems of lines, transformers, computers, and other devices. Land surveying, and navigation via land, water, and air use the Global Positioning System (GPS) to determine routes and locations based on radio waves from satellites. Solar storms are capable of exposing space travelers to dangerous radiation, ruining miniature electronic components on satellites and high-altitude aircraft, inducing damaging electrical currents in power grids, and producing inaccuracies in GPS by altering the media through which GPS radio waves travel. Annually, magnetic storms cause hundreds of millions of dollars in economic losses.

Magnetic storms occur when a mass of plasma containing trapped magnetic fields is ejected from the Sun and strikes the Earth and its atmosphere. This mass, sometimes called a plasma "bubble," travels away from the Sun at about 2 million miles per hour. The "bubble" does not follow a straight course but rides the rotating three-dimensional spiral pattern of the Sun's magnetic field. If a "bubble" leaves the right place on the Sun to reach Earth, it travels the 93-million-mile distance in about 40 hours. Viewed from the Sun, our Earth is a very small target. Therefore, the vast majority of plasma "bubbles" miss Earth, and many that do reach the Earth are too weak to produce a significant
storm. For these reasons, most plasma ejections and "solar flares" observed from Earth and by spacecraft do not produce magnetic storms and are poor predictors of storms. should be applicable for other regions of North America as well.

Our records show that the solar activiy that produces geomagnetic storms is greatest during cycles that repeat about every 11 years. The approaching peak of the 11-year solar (sunspot) cycle, which will occur in the year 2000, increases the possibility of damaging magnetic storms.

The U.S. Geological Survey's Geomagnetism Group in Golden, Colorado, operates a worldwide network of 13 magnetic observatories. Data from these observatories and some of the 65 worldwide observatories in the INTERMAGNET network are transmitted to Golden by satellite and e-mail links (much of it in real-time). These data are continuously monitored to warn of geomagnetic disturbances that could interfere with or damage military and commercial operations and facilities. Networks of ground magnetic observatories, such as those operated by the USGS, can identify the onset of a major magnetic storm and chart its progress during its lifetime of about 3 days. Even a few minutes advanced warning that a storm has begun can save millions of dollars in losses by permitting satellite and power system operators to take mitigating actions.

Whereas forecasting the effects of solar storms is in its infancy, the Nation possesses the technical skills and means to improve understanding, forecasts, and services related to these events. Moreover, the Internet makes it possible to collect and distribute nearly instantaneously any data or modeling result of interest to a user. Cooperating with other agencies and the international scientific community, the USGS is working toward real-time warnings to reduce the hazards and losses from solar storms.

Coping With Solar Storms

Given accurate warnings about solar storms, system operators could use some of these alternatives to avoid or mitigate losses:

For satellites:

· put a satellite "to sleep," or turn off sensitive spacecraft subsystems
· increase satellite monitoring for anomalies
· calculate the best time to adjust a low Earth orbit for drag

For electrical power:

· disconnect links between power grids
· desensitize some automatic control systems, such as second harmonic detectors
· delay power station maintenance and equipment replacement

For communications:

· look for alternative frequencies
· plan means and timing to minimize communications outages

For aerial navigation:

· adjust flight altitude on polar routes to minimize health hazard
· use alternatives to GPS-based takeoff and landing procedures

For surveying:

· delay high-resolution land surveying, exploration, or other research using GPS
· delay high-resolution magnetic surveying that would be degraded by geomagnetic disturbances

For space flight:

· delay activities such as space walks that risk exposing astronauts to radiation

URL: http://geohazards.cr.usgs.gov/factsheets/html_files/geomag/geomag.html

By Arthur W. Green and William M. Brown III
Production and graphic design by Margo L. Johnson

COOPERATING ORGANIZATIONS

Department of Energy
National Oceanic and Atmospheric Administration
National Aeronautics and Space Administration
National Science Foundation
U.S. Air Force
U.S. Navy

For more information, contact:

U.S. Geological Survey National Geomagnetic Information Center
Federal Center, Box 25046
MS 966
Denver, CO 80225-0046 USA
Tel: 303-273-8482
(Dr. Arthur W. Green)
http://geohazards.cr.usgs.gov/

Office of the Federal Coordinator for Meteorological Services and Supporting Research
8455 Colesville Road, Suite 1500
Silver Spring, Maryland 20910 USA
Tel: (301) 427-2002