May 21, 2003 — Everyone is familiar with changes in the weather on Earth. However, "weather" also occurs in space. Just as it affects weather on Earth, the sun can produce dramatic effects in the space environment surrounding the Earth. More important, "space weather" — the collective term used to describe weather effects created in the Sun-Earth environment originating from the sun — is an increasingly important activity in our technology dependent society. The NOAA Space Environment Center has provided space weather products and services to its consumers for more than 40 years.

What is "Space Weather?"
Space weather has been defined as the study, observation and forecasting of solar activities, and their effect on the solar wind, magnetosphere and ionosphere.

• Solar wind is a thin blast of electrified gas (or plasma) emitted by the sun, which blows constantly past the Earth at an average speed of 900,000 mph. Usually, the powerful magnetic field that surrounds our planet deflects it, but sometimes explosive events on the sun — known as coronal mass ejections — hurl large amounts of highly charged particles toward the Earth at speeds of more than five million mph. These “electrified bullets” — mostly protons — result in geomagnetic storms that distort the protective magnetic field and can dramatically affect the Earth’s upper atmosphere.
  
• The magnetosphere is the region of space above the atmosphere (and bounded by the magnetopause) that is under the direct influence of Earth's magnetic field.
  
• The ionosphere is the region of Earth's atmosphere that extends from about 50 to 300 km (31 miles to 186 miles) above the surface of the planet and is made up of multiple layers dominated by electrically charged (or ionized) atoms. During a storm, the ionosphere can be severely altered and in turn affect the near Earth environment. The resultant changes in ion density (sometimes called ionospheric storms) can persist for more than a day after a period of high geomagnetic activity.

Magnetic storms can produce energy equivalents comparable to that released by the atomic bomb that leveled Hiroshima in 1945. The heating and distortion of Earth's upper atmosphere is caused by storm induced changes in the web of magnetic fields and energetic particles that originate from the sun. Space storm events range from coronal mass ejections shooting hundreds of thousands of miles into space to million-mile-per-hour winds blowing charged particles toward Earth.

"Space Weather” Impacts
Today there are a number of man-made and natural systems, which are affected by space weather. It impacts satellites, astronauts and aircraft in the upper atmosphere; can disrupt communications and navigation systems; and can damage power grids, pipelines and even basic Earth systems.

Space Weather Effects in the Upper Atmosphere
Satellites, astronauts and aircraft carry highly advanced components, which are susceptible to the energetic charged particles and plasmas present in the Sun-Earth environment.

• Satellites: When a satellite travels through an energized environment during geomagnetic storms, the charged particles striking the spacecraft cause various portions of it to be differentially charged, leading to the damage (and possibly failure) of the satellite's electronic systems. Furthermore, as technology has allowed spacecraft components to become smaller, their miniaturized systems have become increasingly vulnerable to the more energetic solar particles, which can cause physical damage to microchips and change software commands in satellite-borne computers. Increased solar activity can also cause the atmosphere to heat and expand. For satellites in low-earth orbit, this atmospheric change can exert increased drag on the satellites, causing them to slow down and change orbit. Unless low-Earth-orbit satellites are routinely boosted to higher orbits, they slowly fall, and could eventually burn up in Earth's atmosphere.
  
• Astronauts: Space weather conditions can also be hazardous to humans in space. Astronauts are normally well protected by the shelter of the space station. However, when they venture outside their protective space station, they are vulnerable to the same high doses of particles or radiation as the space station itself. In reality, however, the radiation risk to astronauts is quite small if they work within the Earth's magnetic field and wear layers of protective clothing.
  
• Aircraft: Solar proton events can also produce elevated radiation aboard aircraft flying at high altitudes and over long distances. For example, during air travel from New York City to Tokyo, passengers and crew could be exposed to levels of radiation equaling that of a chest X-ray during an intense solar radiation storm. The most intense solar flares, on the other hand, can be as injurious to humans as the low-energy radiation from a nuclear blast. The penetration of high-energy particles into living cells — measured as radiation dose — can lead to chromosome damage and potentially cancer, while larger doses can be fatal. Although the likelihood of these risks is small, monitoring of solar proton events by satellite can help reduce the threats of human exposure.

Disruption to Communication and Navigation Systems
Because it is composed of electrically charged atoms, the Earth's ionosphere is important for a wide range of communication systems: including high frequency radio, satellite control activities, search and rescue activities, cell phones and pagers and navigation systems — just to name a few. Unfortunately, however, solar flares and other space weather phenomenon can upset the composition of this layer causing communication disruptions at all frequencies.

• Communications: During an ionospheric storm, some radio frequencies are absorbed and others are reflected, leading to rapidly fluctuating signals and unexpected propagation paths. Although TV and commercial radio stations are little affected by solar activity; ground-to-air, ship-to-shore, Voice of America, Radio Free Europe and amateur radio are frequently disrupted. High frequency radiowave communication is most affected because this frequency depends on reflection from the ionosphere to carry signals over great distances. Therefore radio operators using high frequencies rely on solar and geomagnetic alerts to keep their communication circuits up and running. Likewise, some search and rescue, military detection or early-warning systems are also affected by solar activity. Specifically, over-the-horizon radars bounce 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 — as was a major concern in the recent war in Iraq. Lastly, the Federal Aviation Administration routinely receives alerts of solar radio bursts so that it can recognize communication problems and forego unnecessary maintenance.
  
• Navigation Systems: The accuracy of navigation systems using very low frequency signals (i.e., LORAN) depends on knowing the altitude of the ionosphere's lower boundary. Some airplanes and ships use these very low frequency signals to determine their positions. During solar events and geomagnetic storms, however, the altitude of the ionosphere's lower boundary can change rapidly, thus introducing errors of up to several kilometers. If navigators are alerted that a proton event or geomagnetic storm is in progress, they can switch to a backup navigation system. Likewise, global positioning systems operate by transmitting radio waves from satellites to the ground, ships, aircraft or other satellites and therefore are also sensitive to ionospheric changes due to geomagnetic storms.

Space Weather Effects Close to Home
Space weather doesn't just affect objects or people in space — the effects can be felt even closer to home — namely impacts on power grids, pipelines, and even the geology, biology and climate on Earth:

• Electric Power: Geomagnetic storms are harmful to electrical transmission equipment, and damage to transformers and transmission lines can leave entire grids without power. By receiving geomagnetic storm alerts and warnings, power companies can act to minimize damage and power outages.
  
• Pipelines: Rapidly fluctuating geomagnetic fields can induce currents into pipelines carrying valuable fuels. Once this happens, flow meters in the pipeline can transmit erroneous flow information, and the corrosion rate of the pipeline can be dramatically increased. Therefore, pipeline managers routinely receive space weather alerts and warnings to help them maintain an efficient and long-lived system.
  
• Geologic Exploration: Earth's magnetic field is used by surveyors and geologists to determine subterranean rock structures to assist them in mapping efforts and the search for oil, gas or mineral deposits. Because space weather can disrupt the Earth’s magnetic field, individuals in these fields use geomagnetic alerts and predictions to schedule their field activities.
  
• Biology: There is a growing body of evidence that changes in the geomagnetic field affect biological systems. For example, the most closely studied of the 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, which are often much less effective during space weather events.
  
• 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 and temporary decreases of up to one-half percent have been observed. Atmospheric scientists say that this variation is significant and can modify climate over time. Evidence of this can be seen in variations of plant growth, stratospheric wind directions near the equator and ozone depletion, which corresponds to solar cycles.

Why is "Space Weather” More Important Now?
Technology development and usage in the last two decades have increased the number of individuals and systems affected by space weather. Examples of the activities requiring space weather information are depicted in this graphic.

Because there is so much new technology that can be adversely affected by space weather, it is more important now (than ever) to be able to monitor, predict and understand space weather. For example, the millions who use satellite TV, phone and pager services, rely on highly interconnected electric power grids, and those who use GPS to fly the globe are looking for and willing to invest in reliable space weather services. The NOAA SEC provides these products and services to a number of space weather consumers, including: commercial airlines, members of the U.S. power grid infrastructure, the U.S. Department of Transportation, NASA human space flight activities/satellite launch and operations, U.S. Air Force operational support, as well as commercial and public users.

Historical Perspective
The NOAA SEC has been serving space weather customers even before NOAA was established in 1970. SEC services were first requested during the Cold War and the advent of NASA space travel. Over the last 40 years, those using space weather services include the space weather industry, U.S. military, civilian agencies, academics, and the general public — both nationally and internationally:

• Industry (satellite operations, launch teams, power grid operations, telecom companies and space weather service providers)
• U.S. Military (communications, intelligence and operations)
• Civilian Agencies (NASA, Department of Transportation, Department of Energy, FAA and NOAA)
• Education and the General Public
• International Partners

Emerging Activities in Data and Modeling
One of the most exciting advances in space weather forecasting is the world’s most advanced solar storm detector aboard the nation’s newest environmental satellite, GOES-12. The Solar X-ray Imager provides space weather forecasters with real-time images of the sun’s explosive atmosphere, helping them issue timely warnings when solar activity might harm billions of dollars worth of assets, both in space and on the ground. “The Solar X-ray Imager will provide the kind of improvements in space weather forecasting that satellite imagery did for tracking hurricanes,” said retired Navy Vice Admiral Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. “The Solar X-ray Imager will enable us to better protect both commercial and government assets in space and on the ground.” In addition to new data streams (and SXI is only one), the use of that data in modeling will begin to make space weather as predictable as meteorological weather has become.

What does the Future Hold?
Today, each new technological improvement must be evaluated in terms of its response to natural processes, including space weather. For example, GPS-equipped on-board units used to measure truck movement along roads must be resistant to space weather impacts if these are to be used to calculate truck tolls. Likewise, newly developed E911 wireless services must be both accurate and reliable if those are to be used to locate and respond to 911 callers.

Only in the last few decades have we truly come to realize and appreciate the impact space weather can have on people and the Earth in general. Fortunately, many of the adverse effects of the sun's activities on the near-Earth environment can be prevented with SEC space weather products and services. Furthermore, SEC hopes to meet new space weather challenges by knowing what its customers want, maintaining partnerships (both in the United States and abroad), taking advantage of new models and data, and seeing into the future to anticipate space weather developments.

Relevant Web Sites
NOAA Space Environment Center

NEW SOLAR STORM DETECTOR SENDING REAL-TIME IMAGES USED TO WARN OF SUN’S DAMAGING STORMS Solar X-ray Imager Onboard GOES-12 Environmental Satellite

GOES Solar X-ray Imager

NOAA Solar X-Ray Imager — Images

NOAA Space Weather Scales

Media Contact:
Barbara McGehan, NOAA Research (303) 497-6288 or Barbara Poppe, NOAA Space Environment Center (303) 497-3992