Blowing in the Solar Wind: Sun Spots, Solar Cycles and Life on Earth

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1 Blowing in the Solar Wind: Sun Spots, Solar Cycles and Life on Earth The Sun regularly experiences eruptions that shower space with energetic ions. In 1859, a massive solar event occurred with a magnitude that surpassed that of all other recorded events, and the Earth was directly in the path of the storm. Hours after the eruption, sparks began to fly from telegraph wires, fires were ignited by downed wires, equipment operators felt electrical shocks from their telegraph keys and ticker tapes burst into flames. A century and a half later, should a similar solar event occur, more than wires and paper would be at risk. Anatoly Arsentiev Irkutsk, Russia David H. Hathaway National Aeronautics and Space Administration (NASA) Marshall Space Flight Center Huntsville, Alabama, USA Rodney W. Lessard Houston, Texas, USA Oilfield Review Autumn 2013: 25, no. 3. Copyright 2013 Schlumberger. For help in preparation of this article, thanks to Don Williamson. 1. Cliver EW: The 1859 Space Weather Event: Then and Now, Advances in Space Research 38, no. 2 (2006): Boteler DH: The Super Storms of August/September 1859 and Their Effects on the Telegraph System, Advances in Space Research 38, no. 2 (2006): Stephens DL, Townsend LW and Hoff JL: Interplanetary Crew Dose Estimates for Worst Case Solar Particle Events Based on Historical Data for the Carrington Flare of 1859, Acta Astronautica 56, no (May June 2005): Those of us in the energy industry owe our livelihoods to the Sun. The hydrocarbons we search for and produce were formed from organic matter that stored ancient energy that originated within the Sun. In the not too distant past, the Sun was an object of reverence because of its control over our lives. Today, familiarity with and understanding of the Sun has removed much of our sense of veneration; however, we understand that our very existence is based on a relationship to the seemingly unchanging presence of the solar system s shining star. On occasion, however, the Sun s apparent stability is interrupted by powerful displays of its dynamism. One such example occurred on the morning of September 1, From his private observatory, amateur astronomer Richard Carrington observed a cluster of large spots on the surface of the Sun. Suddenly, a brilliant flash of white light a solar flare erupted from the area of the spots. 1 This particular flare was the harbinger of a gigantic coronal mass ejection (CME), which spewed solar plasma into interplanetary space. This massive cloud of charged particles arrived at Earth in less than 18 hours. It proceeded to disrupt the most advanced technology of the day the telegraph. 2 The interaction between the CME and the Earth s magnetic field induced electrical currents in exposed telegraph wires. Current raced through the wires, causing some of them to overheat, fall to the ground and set off fires. Telegraph machines were hit by powerful surges of electricity, which administered electrical shocks to the operators. Some reports described telegraph paper bursting into flames and machines that continued to receive information, even after the operators had disconnected their battery power. Disturbances in the Earth s magnetic field from the effects of the CME caused compass needles to behave erratically. The effects were seen not just on the Earth s surface; auroras, which are normally restricted to Earth s higher latitudes, lit the sky as far south as the Caribbean region. Most experts consider the superstorm of 1859, referred to as the Carrington event, to be the largest recorded solar storm to directly impact the Earth. Data from ice cores dating back 500 years show evidence of geomagnetic storms of varying intensity, but none reached the magnitude of that singular episode. 3 Modern infrastructure has become dependent on a multitude of interconnected systems and devices that are sensitive to electromagnetic and geomagnetic forces. Scientists are concerned that another Carrington-type CME directed toward Earth would wreak havoc, overwhelming electrical power grids and control systems, destroying telecommunications satellites, disrupting global positioning systems (GPSs) and plunging whole continents into darkness and disarray. In 1989, a much smaller geomagnetic storm caused a blackout that pitched the province of Quebec, Canada, into darkness and disrupted power in many locations in the Northeast US. 48 Oilfield Review

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3 250 Quebec blackout 200 Carrington event Sunspot number Date > Sunspot cycles. Scientists have systematically recorded the number of sunspots and numbered the sunspot peaks dating from the 1700s. In several recent cycles, sunspot counts approached or exceeded 200; the current cycle average count is less than 100. According to solar scientists, predicting the next Carrington-class event, or any solar storm, is practically impossible. When solar flares and CMEs occur, scientists have found it difficult to determine whether the Earth lies directly in the path of these streaming ions. In the past few years, the ability to issue alerts about potential damaging solar storms has been improved by the deployment of satellites strategically positioned to monitor the Sun s activity. Although scientists are not able to forecast exactly when solar flares and CMEs will occur, they have discovered a correlation between an increase in the number of sunspots and the frequency and intensity of solar events. Sunspots are dark regions on the Sun, and they follow an 11-year cycle. During sunspot cycle minima, there may be no visible spots; during maxima the number may be greater than 200. Each cycle is numbered, dating to 1755, when observers began to systematically record sunspot activity (above). The Carrington event occurred at the peak of Cycle 10. The US National Oceanic and Atmospheric Administration (NOAA) Space Weather Prediction Center (SWPC) predicts that Cycle 24 will peak in The Sun has been relatively quiet during Cycle 24, but the potential always exists for the Sun to unleash another Carrington-like event. This article discusses the concepts of solar cycles, solar events, CMEs, space weather, solar monitoring and the potential effects of solar storms on modern infrastructure, and it reviews current warning systems. A Not So Benign Sun About 5 billion years ago, a cloud of dust and gas approximately 1.6 trillion km [1 trillion mi] in diameter coalesced to form our solar system. 5 The source of that cloud is believed to be a mix of primordial gas and material from older stars that exploded in massive supernovae. 6 Gravity collapsed the cloud in upon itself, and mutual attraction of the particles accelerated the collapse to form a dense central core. Rotation of the cloud accelerated with contraction, while centrifugal forces flattened the cloud toward the edges, leaving a bulge near the center from which the Sun evolved. As the central core of the Sun continued to collapse, the compression generated heat, which melted and vaporized the dust. About 10 million years after the collapse began, the rate of collapse slowed because the pull of gravity was balanced by the pressure of hot gases. The rising core temperature initiated nuclear reactions, and the heat and pressure stripped away electrons, leaving mostly plasma a mixture of protons and electrons. The gravitational pull of the Sun continued to compress the plasma in its core to densities nearly ten times that of lead and heated the plasma to nearly 16 million C [29 million F], at which point fusion reactions can occur. In the Sun s fusion reaction, hydrogen atoms fuse and form helium. During the reaction, some of the original mass is converted into heat and photons. The photons radiate outward, first traveling through the radiative zone and then, after millions of collisions, arrive at the region near the surface the convection zone (next page, top right). From the convection zone, the photons eventually leave the Sun. Traveling at the speed of light, photons cover the 150 million km [93 million mi] between the Earth and Sun in about eight minutes. The photons emitted by the Sun cover a broad band of the electromagnetic spectrum from high-energy X-rays to radio waves. The Earth is constantly bombarded by this energy, but because the atmosphere shields it from most of the emissions, only a few specific frequencies mostly those of ultraviolet light, visible light and radio waves reach Earth s surface. A self-generated magnetic field is a by-product of the Sun s fusion reactor, rotation and constantly moving mass of plasma in the convection zone. Magnetic field lines are generally aligned with the axis of rotation of the Sun. The field exhibits a dipolar nature analogous to that of the Earth, with its north and south magnetic poles. However, unlike Earth s magnetic field, the Sun s magnetic field reverses polarity on a regular basis, coinciding with the midpoint of the 11-year sunspot cycle peak. The Sun s rotating magnetic field also generates a current sheet that extends billions of kilometers from the Sun out into space. When the magnetic polarity reversal occurs a process that started in the summer of 2013 for Cycle 24 the current sheet becomes highly contorted. The Earth dips in and out of the current sheet while orbiting the Sun, potentially creating stormy space weather conditions Oilfield Review

4 On the surface of the Sun, magnetic field lines emerge to form sunspots. Magnetic field lines may encompass volumes that are quite large the planet Jupiter, which is 150,000 km [90,000 mi] in diameter, could easily fit inside some of them (below right). Coronal loops also form at the surface, following the magnetic field lines. During solar sunspot peaks, the number of coronal loops increases and magnetic field lines often become twisted. This twisting stores massive amounts of energy that is eventually released in the form of solar flares, CMEs and other events. Space weather is punctuated by bursts of energy from these magnetic disturbances. Prominence Convection zone Radiative zone Core Photosphere Sunspots Space Weather Space weather is defined as the physical conditions in the space environment that have the potential to affect space-borne or ground-based technology systems. 8 Space weather is greatly influenced by the energy carried from the Sun by the solar wind, and it can disturb conditions immediately around the Earth. Charged particles mainly protons and electrons make up the solar wind. These particles are emitted in all directions from the Sun. Solar wind speed, density and composition determine associated effects on the Earth. 9 Geomagnetic storms, ionospheric disturbances and aurora emissions are all manifestations of space weather. Coronal mass ejections and associated shock waves are the most violent components of space weather, and they tend to compress the Earth s magnetosphere and trigger geomagnetic storms. Earth s magnetosphere is a bullet-shaped bubble that protects the planet s surface from harmful radiation. The magnetosphere shields the Earth from fast-moving ions by deflecting and concentrating them at the Earth s north and south poles. The Van Allen radiation belts trap charged particles that leak through the magnetosphere, further protecting Earth s surface from harmful electromagnetic radiation. 4. NOAA: Mild Solar Storm Season Predicted, National Oceanic and Atmospheric Administration (May 8, 2009), solarstorm.html (accessed September 4, 2013). 5. Friedman H: The Astronomer s Universe: Stars, Galaxies and Cosmos. New York City: Ballantine Books, Naturally occurring heavy elements found on Earth, such as uranium and plutonium, could have come only from an extremely violent nuclear reaction such as a supernova. 7. Phillips T: The Sun s Magnetic Field Is About to Flip, NASA (August 5, 2013), goddard/the-suns-magnetic-field-is-about-to-flip (accessed August 28, 2013). 8. Hanslmeier A: The Sun and Space Weather, 2nd ed. Dordrecht, The Netherlands: Springer, Feldman U, Landi E and Schwadron NA: On the Sources of Fast and Slow Solar Wind, Journal of Geophysical Research 110, no. A7 (July 2005): A A Coronal hole Corona > The Sun s structure. Fusion reactions take place in the Sun s central core. The pull of gravity accelerates hydrogen nuclei inward, toward the Sun s center, where they fuse and form helium; the reaction releases energy. The energy in the form of photons and other elementary particle by-products rises through the Sun s radiative and convection zones and then exits from the photosphere. The corona is the Sun s outer atmosphere, a layer of plasma surrounding the chromosphere. Features displayed on the Sun s surface seen here include a prominence, solar flares, sunspots and a coronal hole. [Illustration courtesy of the US National Aeronautics and Space Administration (NASA).] > The Sun s magnetic field lines. Convoluted magnetic field lines (green) may extend thousands of kilometers out from the surface of the Sun. (Image courtesy of the NASA Goddard Space Flight Center Scientific Visualization Studio.) Flare Chromosphere Autumn

5 Interplanetary magnetic field lines Solar wind Bow shock Plasmasphere Van Allen radiation belts > Earth s magnetosphere. The magnetosphere, the area of space around the Earth created by Earth s magnetic field, is a dynamic structure that responds to variations in solar activity and space weather. Solar wind, which compresses the sunward side of the magnetosphere, determines its shape. A supersonic shock wave the bow shock forms on the sunward side of Earth. Most of the solar wind particles are slowed at the bow shock and directed around the Earth in the magnetosheath. The solar wind pulls at the magnetosphere on the Earth s night side, extending the length of the magnetosphere up to 1,000 Earth radii, creating what is known as the magnetotail. The outer boundary of Earth s confined geomagnetic field is called the magnetopause. Trapped charged particles the Van Allen radiation belts, the plasmasphere and the plasma sheet reside within the magnetosphere. (Adapted from an image courtesy of Aaron Kaase, NASA Goddard Space Flight Center.) Penumbra Magnetosheath Umbra Magnetopause Plasma sheet Penumbra Umbra Magnetotail > Sunspots. Regions on the Sun that appear darker than the rest of the disk, sunspots are formed by concentrated magnetic fields that project through the hot gases of the photosphere out to the Sun s surface. These magnetic fields create cooler, darker regions called sunspots. The dark center of a sunspot is called the umbra; the light area around the umbra is the penumbra. Sunspots occur in groups and frequently in pairs. The two spots in a pair have opposite magnetic polarities. (Photographs courtesy of NASA.) The region of the magnetosphere away from the Sun is elongated by the pressure of the solar wind, and the shape varies with space weather conditions (left). Space weather has the potential to catastrophically disrupt the near-earth environment. The World Meteorological Organization (WMO), an agency of the United Nations, established the Interprogramme Coordination Team on Space Weather (ICTSW) to address concerns of potential disruptions to life on Earth caused by space weather. 10 Experts from twenty countries and seven international organizations participate in the program. In the US, NOAA is responsible for monitoring terrestrial as well as space weather. The NOAA SWPC constantly monitors data about the Sun and forecasts solar and geophysical events that may impact satellites, navigation systems, power grids, communications networks and other technology systems. 11 Because of the correlation of increases in sunspot numbers with solar storms, scientists are on high alert during solar maxima. Sunspots About 2,800 years ago, Chinese astronomers made the first recorded observation of sunspots. 12 The invention of the telescope in the 1600s made it possible to study and record the ever-changing face of the Sun more closely. Reliable and systematic records of sunspots date back to the 1700s. In the mid-1800s, German astronomer Samuel Heinrich Schwabe first identified a 10-year pattern of the rise and fall of sunspots the sunspot cycle. Swiss astronomer Johann Rudolf Wolf later characterized the 11-year period for the cycle and developed a formula for quantifying sunspot activity, the Wolf number, which is still in use today. 13 The cycle is not exactly 11 years but has varied from 9 to 14 years. Sunspots form where concentrated magnetic field lines project through the hot gases of the photosphere and correspond to regions that are cooler than the surrounding surface. Although they appear darker than the rest of the solar disk, removed from the Sun, they would be brighter than anything else in the solar system (left). The importance of the complex magnetic fields to the activity of the Sun has been realized only within the past 100 years. American astronomer George Ellery Hale first reported solar magnetism in He determined the presence of magnetic fields by measuring changes to intensity and polarization of light emitted from atoms in the Sun s atmosphere. 14 Hale and his colleagues demonstrated that sunspots contain strong magnetic 52 Oilfield Review

6 fields and that all the sunspot groups in a given solar hemisphere have the same magnetic polarity signature. Furthermore, sunspot polarity correlates to the Sun s magnetic field orientation in a specific solar cycle, which reverses with each cycle. The hemisphere that has a north magnetic polarity at one solar minimum has a south magnetic polarity at the next solar minimum. Sunspots typically range in size from 2,500 to 50,000 km [1,500 to 30,000 mi] and cover less than 4% of the Sun s visible disk. In comparison, the Earth s diameter is about 12,700 km [7,900 mi]. Sunspots typically have a lifetime of a few days to a few weeks and tend to be concentrated in two midlatitude bands on either side of the Sun s equator. During the early part of the solar cycle, sunspots are most commonly seen around latitudes of 25 to 30 north and south of the equator. Later in the cycle, they appear at latitudes of 5 to 10. Sunspots rarely occur at latitudes above 50. The intense magnetic fields associated with sunspots often create arching columns of plasma called prominences that appear above sunspot regions (right). Some prominences may hang suspended above the solar surface for several days. When these massive loops of energy become twisted, they store energy that can violently erupt and blast coronal material outward from the Sun as a solar flare or a CME. Prominence > Solar prominence photographed on September 23, The space-based Solar and Heliospheric Observatory (SOHO) captured this image of an eruptive prominence using extreme ultraviolet frequencies. The release of energy from twisted magnetic field lines flings plasma above the Sun s surface. [Photograph courtesy of the SOHO Extreme Ultraviolet Imaging Telescope (EIT) consortium.] Solar Flares and CMEs The energy source for solar flares originates in the tearing and reconnecting of magnetic field lines, and the strong magnetic fields in active sunspot regions often give rise to solar flares (right). These intense, short-lived releases of energy are our solar system s most explosive events. During a solar flare, temperatures soar to 5 million K, and vast quantities of particles and radiation can be blasted into space, but a flare usually ends within 20 minutes. 10. For more on WMO and ICTSW: WMO Scientific and Technical Programs, World Meteorological Organization, (accessed August 1, 2013). 11. For more on the SWPC: NOAA National Weather Service Space Weather Prediction Center, noaa.gov/aboutus/index.html (accessed August 13, 2013). 12. Clark DH and Stephenson FR: An Interpretation of the Pre-Telescopic Sunspot Records from the Orient, Quarterly Journal of the Royal Astronomical Society 19, no. 4 (December 1978): Hathaway DH: The Solar Cycle, Living Reviews in Solar Physics 7 (2010): Alexander D: The Sun. Santa Barbara, California, USA: Greenwood Press, > Solar flare. The NASA Solar Dynamics Observatory (SDO) captured this image of a solar flare on May 22, The image captures light in the 13.1-nm wavelength, which highlights material heated to intense temperatures during a flare. The teal coloration is typical of images using this wavelength. (Photograph courtesy of the NASA SDO.) Autumn

7 > Auroras at high latitudes. Charged particles from solar wind and geomagnetic storms follow the Earth s magnetic field lines and can ionize gases in Earth s upper atmosphere. Ionized oxygen molecules emit green to brownish-red light; ionized nitrogen emissions are blue or red. The aurora borealis (left) was photographed from the International Space Station over the Midwest US on January 25, The photograph of the aurora australis (right) captured by the NASA IMAGE satellite on September 11, 2005, was taken four days after a solar flare. The aurora encircles the South Pole and would appear as a curtain of light if observed from ground level. (Photographs courtesy of the NASA International Space Station and IMAGE Science Center.) During the peak of the sunspot cycle, several flares may occur daily. When a flare erupts, ultraviolet and X-ray radiation from the flare travel at the speed of light, arriving at the Earth in about Sun s diameter 8 minutes. A day or two later, high-energy particles may also arrive at the Earth, producing auroras lights in the polar night skies and affecting radio communications (above). 15 > CME image captured from space on October 22, The Large Angle and Spectrometric Coronagraph (LASCO), on board the NASA SOHO satellite, captured this image in which plasma was hurled in the direction of Mars. The Sun is obscured by a disk that allows the instrument s sensor to focus on the emissions from the Sun s surface, which enhances the observation of the corona by blocking direct light from the Sun. The white circle on the disk represents the size and location of the Sun s surface. (Photograph courtesy of the SOHO EIT consortium.) During some solar flares, a more violent reaction may occur a coronal mass ejection (below left). When the twisted magnetic field lines cross, their stored energy explodes outward with tremendous force. A CME occurs when the force of the released energy flings a mass of superheated plasma from the Sun s surface into space. CMEs vary in intensity and magnitude. A large CME can contain kg [ lbm] of matter that may be accelerated into space at several million kilometers per hour. The speed at which the plasma travels depends on the original energy release. A high-energy CME can arrive at the Earth in as little as 16 hours, but lower-energy releases may take days to make the journey. Upon impact by a CME, the Earth s magnetosphere temporarily deforms, and the Earth s magnetic field is distorted. During these disruptions, Earth-orbiting satellites are exposed to ionized particles, compass needles can behave erratically and electrical currents may be induced in the Earth itself. These events geomagnetic storms can disrupt technical infrastructure on a global scale. Because of the risks associated with solar storms and CMEs, scientists constantly monitor space weather. At a solar minimum, the estimated occurrence of a CME is about one event every five days compared with about 3.5 per day at a solar maximum. Although this may appear to put the planet in frequent jeopardy, the probability that a CME will be directed toward Earth is small. In comparison to the Sun and the expanse of the solar 54 Oilfield Review

8 L4 Moon Earth L3 L1 L2 Sun L5 > Lagrange points. Scientists have identified five points (L1 through L5) associated with Earth s orbit of the Sun where satellites can maintain stable orbits. These locations, called Lagrange points (green), are shown here with the gravitational potential lines (gray lines) established by the Sun-Earth system. These positions in space correspond to regions where the gravitational forces of attraction (red arrows) and repulsion (blue arrows) are in balance. The Wilkinson Microwave Anisotropy Probe (WMAP) is located around position L2, which is about 1.5 million km [930,000 mi] from the Earth. The WMAP spacecraft aligns with the Sun-Earth axis, similar to a geostationary orbit, but course corrections are required to maintain its relative position. The illustration is not to scale. (Illustration courtesy of the NASA WMAP Science Team.) system, the Earth is tiny; most solar storms fire harmlessly away from Earth or deliver only a glancing blow. But CMEs do strike the Earth. The Carrington event is not the only CME that has directly impacted Earth. In 1984, US President Ronald Reagan was airborne in the presidential plane Air Force One over the Pacific Ocean during a solar storm. The storm disrupted high-frequency radio communication for several hours and effectively isolated Air Force One from the rest of the world. In July 1989, a portion of Quebec, Canada, was blacked out for more than nine hours because a solar storm overloaded circuit breakers on the power grid. More than 200 related events were reported across North America. The US National Academy of Sciences reported that had the storm been a Carrington-class event, cost could have ranged from US$ 1 to 2 trillion in damage to critical infrastructure, and recovery could have taken 4 to 10 years. 16 Forecasting Space Weather Technologies that are sensitive to changes in the near-earth electromagnetic environment caused by geomagnetic storms include satellite communication systems, global positioning systems (GPSs), computer networks, electric grids and cell phone networks. Civilization has become increasingly dependent on these technologies, and space weather has the potential to disrupt them. Thus the need for accurate space weather forecasts has become imperative. The NOAA SWPC serves as the primary warning center for the US and provides information to the International Space Environment Service (ISES). ISES a collaborative network of space weather providers monitors space weather, provides forecasts and issues alerts from regional warning centers. Using a wide array of terrestrial and space-based sensors, scientists continually monitor the space environment for events that might impact Earth. About 1.6 million km [1 million mi] from the Earth, in the general direction of the Sun, a group of NASA satellites monitors the Sun and solar wind at the L1 Lagrange point (above). 17 In what is analogous to a geostationary orbit, spacecraft remain in fixed positions with the Earth s orbit relative to the Sun. The Solar and Heliospheric 15. Comins NF and Kaufmann WJ: Discovering the Universe, 9th ed. New York City: W. H. Freeman and Company, National Research Council of the National Academies: Severe Space Weather Events Understanding Societal and Economic Impacts: A Workshop Report, Washington, DC: National Academies Press, May The Lagrange points, named for Italian-French mathematician Joseph-Louis Lagrange, are the five positions where a small mass can maintain a constant pattern while orbiting a larger mass. The L1 point lies in a direct line between the Earth and Sun. For more on the Lagrange points: The Lagrange Points, National Aeronautics and Space Administration, (accessed August 1, 2013). Autumn

9 > The NASA Advanced Composition Explorer (ACE). Launched on August 25, 1997, the ACE satellite, a crucial component of the NASA space weather monitoring fleet, is stationed at Lagrange point L1. From this position, the satellite records radiation emitted from the Sun, the solar system and the galaxy. When bursts of solar material stream toward Earth, instruments on board ACE record the increase in the number of particles and transmit this information to scientists on Earth who use these data to warn of impending space weather events. Alerts and warnings are issued to relevant organizations and posted online by the NOAA SWPC. (Illustration courtesy of NASA.) Relative size of Earth > Space weather monitoring by SOHO. The SOHO satellite (right) was launched in December SOHO is a joint project between the European Space Administration (ESA) and NASA to study the Sun from its deep core to the outer corona and the solar wind. The satellite weighs about 17.8 kn [2 tonus], and its solar panels extend about 7.6 m [25 ft]. This solar eruption (left), which lasted four hours, was photographed on December 31, 2012, by the Extreme Ultraviolet Imaging Telescope (EIT) in 30.4-nm emission. Most of the plasma fell back to the Sun s surface. The Earth is shown for scale. (Solar photograph courtesy of the SOHO EIT consortium; satellite image courtesy of Alex Lutkus.) Observatory (SOHO), the Advanced Composition Explorer (ACE) and other space-bound assets monitor the Sun s surface and track CMEs from this position. 18 Hours before a CME impact, satellite sentinels at the L1 point can anticipate its arrival at the Earth s magnetosphere (left). The SOHO satellite, launched in 1995, allows scientists to constantly monitor the Sun (below left). This satellite is one of the most reliable NASA and European Space Agency (ESA) forecasting tools, providing scientists with data to help them forecast space weather and estimate potential consequences. The Large Angle and Spectrometric Coronagraph (LASCO), one of 12 instruments on board SOHO, records images of CMEs launched from the Sun. Using LASCO data, the SWPC has two to three days of advanced warning for the onset of geomagnetic storms. The Solar Dynamics Observatory (SDO), developed at the NASA Goddard Space Flight Center in Greenbelt, Maryland, USA, and launched on February 11, 2010, is part of a five-year NASA mission to study the Sun and its influence on space weather (next page). 19 Several devices are on board the satellite, including the Extreme Ultraviolet Variability Experiment and the Atmospheric Imaging Assembly. The helioseismic and magnetic imager provides real-time maps of magnetic fields on the surface of the Sun and measures their strength and orientation. Changes and realignment of the Sun s magnetic fields are early indications of potential eruptions and are crucial for the prediction of space weather and geomagnetic storms. Instruments on board the satellite can also characterize the interior of the Sun, where the magnetic fields originate. From SDO data, scientists are gaining a better understanding of solar activity and space weather. Geomagnetic Storms Brewing Geomagnetic storms that disrupt activities on Earth are infrequent, although their consequences are significant; solar storms have the potential to disturb the entire planet. The technologies that define modern society are susceptible to the effects of space weather. Induced currents can disrupt and damage modern electrical power grids and cripple satellites and communication systems. For the oil and gas industry, geomagnetic storms can adversely affect pipelines and supervisory control systems and disrupt surveying and geosteering operations while drilling. 56 Oilfield Review

10 Filament Magnetic field lines > The Solar Dynamics Observatory (SDO). The SDO satellite (left) was launched in February 2010 as part of the NASA Living with a Star Program, which studies solar variability and potential impacts on Earth and space. By examining the solar atmosphere on small scales and capturing emissions at many wavelengths simultaneously, the study hopes to determine how the Sun s magnetic field is generated and structured and how stored magnetic energy is converted and released into the heliosphere and space. This image of the Sun s magnetic field lines (right), captured on June 4, 2013, was taken in extreme ultraviolet light and highlights the bright coils of magnetic field lines rising up in the background above an active region. A filament, which appears as a darker region on the Sun s surface, can also be seen. (Photograph and image courtesy of the NASA SDO.) The most crippling effects of geomagnetic storms come from geomagnetically induced currents (GICs) that flow through electrical power grids. At the most benign level, GICs can trip circuit breakers, but stronger events can destroy transformers and trigger component meltdown throughout large geographic areas. GICs damage transformers by driving them into half-cycle saturation the core of the transformer is magnetically saturated on alternate half cycles. A GIC-induced voltage level of as little as 1 to 2 volts per kilometer or current of 5 amperes is sufficient to drive transformers into saturation in one second or less. 20 Engineers have measured GIC currents as high as 184 amperes during geomagnetic storms; these levels are far above that required to overload electrical grids. 21 In the event of a severe GIC incident, the time required to restore damaged equipment and bring large populations back online might be measured in weeks, months or even years. When the charged plasma cloud of a CME collides with Earth s atmosphere, transient magnetic waves alter Earth s normally stable magnetic field; the effects can last for several days. These magnetic disturbances may cause voltage variations along the Earth s surface, inducing electrical currents between grounding points because of the voltage potential differences. GICs in this form are particularly detrimental to transformers typically found in power plants and electrical distribution substations. Several factors dictate the susceptibility of a given electrical power grid system to disruption and damage from solar storms. A power grid s proximity to Earth s polar latitudes generally increases its risk for failure or malfunction. In addition, sites located in regions of low ground 18. For more on SOHO: (accessed August 13, 2013). For more on ACE: (accessed August 13, 2013). 19. For more on SDO: (accessed August 13, 2013). 20. For more on detrimental effects on power grids: Barnes PR, Rizy DT, McConnell BW, Tesche FM and Taylor ER Jr: Electric Utility Industry Experience with Geomagnetic Disturbances, Oak Ridge, Tennessee, USA: Oak Ridge National Laboratory, ORNL-6665, September Odenwald S: The 23rd Cycle: Learning to Live with a Stormy Star. New York City: Columbia University Press, Autumn

11 Typical auroral zone location Region conductivity, S/m CANADA 1 to to to to to 10 3 Auroral zone extreme on March 13, 1989 UNITED STATES CANADA MEXICO UNITED STATES Highest risk Medium risk Connected power grids MEXICO > Power system susceptibility. Power systems in areas with the lowest ground conductivity (left, red and darkest yellow) are the most vulnerable to the effects of intense geomagnetic activity. The high ground resistance beneath these areas facilitates the flow of geomagnetically induced currents (GICs) in power transmission lines. Auroral zones for North America are susceptible to GICs because of their proximity to polar regions. (Data from the American Geophysical Union and the Geological Survey of Canada.) For the US, scientists produced a map based on scenarios for existing power systems to determine their vulnerability to geomagnetic storms (right). Should a storm 10 times larger than the 1989 storm that disrupted power systems in Quebec arrive at Earth, the systems most at risk have been identified (red). The blue lines encircle the largest population centers served by at-risk systems. (Adapted from the National Research Council of the National Academies, reference 16.) conductivity, such as igneous rock provinces, are more susceptible to GIC effects (above). The interconnectivity of power grids can exacerbate the potential for large-scale problems. During the July 1989 solar storm, many related events were reported. These events included a transformer failure at the Salem nuclear plant in New Jersey, USA; New York Power losing 150 MW the moment the Quebec power grid went down; and the New England Power Pool, an association of power suppliers, losing 1,410 MW. Service to 96 electrical utilities 58 in the New England region of the US was interrupted before power companies could bring other reserves online.22 Damage caused by energized particles emitted from the Sun is not limited to terrestrial systems. Satellites, space exploration vehicles and manned space missions can be affected by solar emissions, some of which are too weak to enter Earth s magnetic field. For instance, weak solar flares and CMEs may produce solar proton events (SPEs) that are mostly unnoticed on the surface of the Earth. However, SPEs can cause significant damage to equipment located outside Earth s protective shield. When high-energy charged particles collide with satellites, electrons create a dielectric charge within the spacecraft. This static charge can destroy electronic circuit boards, alter and scramble stored data and affect control instructions stored in computer memory. Although these effects may result in a complete satellite failure, damage may often be corrected by simply rebooting onboard computers. Oilfield Review

12 If the solar arrays that provide power to satellites are struck by high-energy protons from SPEs and CMEs, the silicon atoms in the solar cell matrix may shift positions, which increases the internal resistance of the solar cells and reduces electrical output. A single solar storm event can decrease panel life expectancy by years. If attitude control systems on satellites used to correct their orientation and position are damaged by high-energy particle events, a satellite can lose its orbital control, which may result in an unplanned and premature reentry into Earth s atmosphere. 23 Satellites play such a crucial role in communications that a loss could affect television, cable programming, radio service, weather data, cell phone service, automated banking services, commercial airline systems and GPS and navigation services. Routine losses as a result of satellite malfunction and premature asset failure caused by solar storms are estimated in the billions of US dollars. Consequences of solar storms may not be limited to electrical damage. The July 1989 solar storm caused compression of the Earth s magnetosphere, reducing its typical depth of more than 54,000 km [33,500 mi] to less than 30,000 km [18,640 mi], well inside the Earth s geosynchronous region where satellites orbit. As the Earth s atmosphere was bombarded by energetic particles and compressed by the solar wind, the density of the upper atmosphere increased by a factor of 5 to 10. The increased drag on low-earth orbit satellites caused orbital decay the U.S. Air Force Space Command reported losing track of more than 1,300 orbiting objects that fell to lower altitudes. 24 In a separate event, on March 13, 1989, NOAA reported the loss of the GOES-7 weather satellite. Circuit problems caused by a shower of energized particles rendered most of its systems useless. Critical solar power arrays on GOES-7 lost 50% of their efficiency. Engineers with NASA reported many other satellites experienced electrical failures that temporarily shut down onboard computers. 25 The storm disrupted communications on the Earth and between ground controllers and orbital satellites. Oil and gas pipeline and distribution systems are also vulnerable. In the event of a geomagnetic storm, operators may immediately lose supervisory control and data acquisition (SCADA) systems. Operators must also consider the long-term effects associated with increased pipeline corrosion rates. Cathodic protection systems used on pipelines to minimize corrosion maintain a negative potential with respect to the ground. During solar storms, GIC events in a pipeline reduce the Azimuth, degree Magnetic storm 259 3,600 3,700 3,800 3,900 4,000 4,100 4,200 4,300 4,400 4,500 4,600 4,700 Depth, ft > Geomagnetic storms and directional drilling. Directional drillers use MWD tools to determine drillbit orientation and position; these measurements depend on data derived from magnetometers and accelerometers. During geomagnetic storms, magnetometers may provide erroneous readings. A solar storm occurred while an operator drilled a North Sea well, and the MWD drilling azimuth measurement (blue) was affected by the geomagnetic storm. Engineers corrected the data using a technique developed by the British Geological Survey that adjusts for space weather. The results provided a more accurate well location (green). (Adapted from Clark and Clarke, reference 28.) effectiveness of the cathodic protection, which may increase long-term corrosive effects. 26 The level of impact is affected by the specifics of pipe construction materials, pipeline diameter, bends, branches, insulated flanges and the integrity of insulation materials. Operators are also concerned about the large percentage of modern oil and gas wells that are drilled directionally. Drillers must use strict well trajectory plans to control borehole position relative to the reservoir and to avoid collision with nearby wellbores. Directional drilling relies on instruments that make real-time measurements to determine and track the subsurface location of the drilling assembly. Triaxial magnetometers measure the strength of the Earth s magnetic field, and triaxial accelerometers are used to correct magnetometer data for position, motion and orientation. Gyrocompasses using gyroscopes and the rotation of the Earth to find geographic north are also deployed on wireline to acquire precise directional surveys. 27 Disturbances in the Earth s magnetic field arising from electric currents flowing in the ionosphere and the magnetosphere can affect these measurements (above). Mirror currents may also be induced in the Earth and oceans by variations in the Earth s magnetic field. These external magnetic fields are affected by the solar wind, Drilling azimuth Corrected azimuth the interplanetary magnetic field and the Earth s magnetic core. Well placement engineers must be acutely aware of geomagnetic disturbances and variations in Earth s magnetic field to ensure proper borehole placement. 28 (See Geomagnetic Referencing The Real-Time Compass for Directional Drillers, page 32.) The Earth s climate is also susceptible to space weather and to particle emissions from the Sun. Although the Sun appears to be a constant energy source, scientists have demonstrated 22. North American Electric Reliability Corporation (NERC): Effects of Geomagnetic Disturbances on the Bulk Power Systems, Atlanta, Georgia, USA: NERC (February 2012). 23. Odenwald, reference Alexander, reference Odenwald, reference Zurich Financial Services Group: Solar Storms: Potential Impact on Pipelines, internet/main/sitecollectiondocuments/insight/ solar-storms-impact-on-pipelines.pdf (accessed September 5, 2013). 27. Ekseth R and Weston J: Wellbore Positions Obtained While Drilling by the Most Advanced Magnetic Surveying Methods May Be Less Accurate than Predicted, paper IADC/SPE , presented at the IADC/SPE Drilling Conference and Exhibition, New Orleans, February 2 4, Clark TDG and Clarke E: 2001 Space Weather Services for the Offshore Drilling Industry, poster presentation in Proceedings from the ESA Space Weather Workshop: Looking Towards a Future European Space Weather Program. Noordwijk, The Netherlands, December 17 19, Autumn

13 Temperature Northern Hemisphere Temperatures over the Last 1,000 Years Medieval warm period Mean temperature Sunspot numbers 400 Years of Sunspot Observed Data 250 Less-reliable observation data 200 Reliable observation data Maunder Minimum Dalton Minimum Date Modern maximum 2000 Little Ice Age Date > Sunspot cycles and terrestrial weather. Scientists have not reached consensus regarding the effects of solar activity on the Earth s climate and weather. Most, however, would agree that the Sun is the primary heat source for the Earth, thus the major driver of climate. Some scientists have tried to draw a correlation between the absence of sunspots during the Maunder Minimum (top) a 70-year period in the 17th century and the Little Ice Age that affected much of the Earth, especially Europe (bottom). The Dalton Minimum, another period of low sunspot occurrences around 1800, corresponded to lower than average global temperatures, as well. The rise in total average number of sunspots (black) beginning in the 1900s appear to correspond to increases in global temperatures. Although a close examination of the data points to other factors producing temperature variations, such as volcanic eruptions and changes in CO 2 levels, some observers propose solar activity as a major component in climate and temperature fluctuations. The activity of Solar Cycle 24 is comparable to that in the cycles around 1800 rather than those of the 20th century. A century from now, scientists may be able to look back and debunk or validate the causal relationship of sunspots to climate change. that the base energy output of the Sun varies up to 0.5% on short timescales and 0.1% over the 11-year sunspot cycle. Considered significant by atmospheric scientists, these fluctuations can affect Earth s climate. Variations in plant growth have been correlated with the 11-year sunspot cycle and 22-year magnetic period of the Sun, as evidenced in tree ring records. 29 Although the solar cycle has been relatively steady during the last 300 years, during a 70-year period in the 17th century, few sunspots were observed. This period, referred to as the Maunder Minimum, also coincided with the timing of the Little Ice Age in Europe. Some scientists have theorized that this is evidence of a Sun-Earth climate connection (above). 30 Recently, scientists have proposed a more direct link between the Earth s climate and solar variability. For instance, the stratospheric winds near the Earth s equator 29. For recent research on solar cycles effects on Earth s weather: Meehl GA, Arblaster JM, Matthes K, Sassi F and van Loon H: Amplifying the Pacific Climate System Response to a Small 11-Year Solar Cycle Forcing, Science 325, no (August 2009): Weng H: Impacts of Multi-Scale Solar Activity on Climate. Part I: Atmospheric Circulation Patterns and Climate Extremes, Advances in Atmospheric Sciences 29, no. 4 (July 2012): Weng H: Impacts of Multi-Scale Solar Activity on Climate. Part II: Dominant Timescales in Decadal- Centennial Climate Variability, Advances in Atmospheric Sciences 29, no. 4 (July 2012): Solar Storm Warning, NASA (March 15, 2006), 10mar_stormwarning.html (accessed August 18, 2013). 33. Zurich Financial Services Group, reference 26. change direction with each solar cycle. Studies are underway to determine how this wind reversal affects global circulation patterns, weather and climate. 31 The Next Big Event Geomagnetic storms, although infrequent, can severely impair critical infrastructures of modern society. Because we are increasingly dependent on susceptible technologies in our interconnected global economy, solar storms have the potential to create havoc on a worldwide scale. The scientific community is working to improve its understanding of the technical aspects of this threat and the related vulnerabilities in various industry segments to better manage risk. The science of space weather forecasting is still in its infancy. Scientists cannot accurately forecast the number of sunspots before the start of a solar cycle or predict geomagnetic storm activity, although some organizations do make attempts. A decade ago, before the start of Cycle 24, some forecasters were predicting the most intense solar maximum in 50 years and that the cycle might result in devastating geomagnetic storms. 32 But those forecasts were wrong. The sunspot activity of Solar Cycle 24 has been the lowest in more than 100 years, barely half the activity level of Cycle 23. Some scientists speculate that the Sun is entering another quiet period similar to the Maunder Minimum and are asking questions: Will global climate effects be similar to those of the Little Ice Age during the Maunder Minimum or is there no direct correlation between sunspots and terrestrial climate? Or is this just the quiet before the storm? Even during a relatively low-amplitude solar cycle, a CME can be triggered that makes a direct hit on planet Earth. The recurrence probability of the 1859 Carrington event is estimated at 1 in 500 years, and the recurrence probability of the 1989 Quebec storm is estimated at 1 in 150 years. 33 Although scientists, engineers and risk managers are concerned about the potential damage of another Carrington-type event, they have many more tools at their disposal to help them predict and react when such an event occurs. These tools allow the scientific community to remain vigilant to the Sun s activity and be prepared to act. The list of solar storm consequences grows in proportion to our dependence on electromagnetically sensitive technology systems. The SWPC and ISES, working with many national and international partners, continue to develop improved monitoring and space weather modeling capabilities. Advances in Earth-bound and satellite-based data acquisition systems, along with modeling and a better understating of our interlinked relationship with the Sun, hold promise of reducing our exposure risk when the Earth is directly in the path of the next great solar storm. TS 60 Oilfield Review