CHAPTER 4 EFFECT OF SOLAR FLARE AND CME ON EARTH
CHAPTER 4 EFFECTS OF SOLAR FLARE AND CME ON EARTH 4.1 Introduction The solar flare is a localized explosive release of energy, high energetic particles and protons that appears as a sudden, short lived brightening of an area in the chromosphere. Solar flares release their energy mainly in the form of electromagnetic radiation and energetic particles. Flares are rarely visible in white light that is emitted at the photospheric level but visible in EUV and X-ray wavelengths. These X-ray and EUV waves travel at the speed of light, taking only 8 minutes to reach us here at earth. The energy released in the process of solar flares increased the velocity and acceleration of solar wind which is affecting the space weather. The second mechanism in which the sun affects earth is through the impact of matter from the sun. Plasma, or matter in a state where electrons wander freely among the nuclei of the atoms, can also be ejected from the sun during a solar disturbance. This bundle of matter is called a CME which flows from the sun at a speed of over 2 million kilometer per hour. It takes about 18 to 72 hours for a CME to reach us from the sun. Since CMEs are large masses of ionic particles moving through interplanetary space, their energy is kinetic. The kinetic energy of a CME is around 10 23 to 10 24 Joule (Vourlidas et al., 2002). When a CME impacts the earth's magnetosphere, it temporarily deforms the earth's magnetic field and inducing large electrical ground currents in earth. Explosion powered by the sun s magnetic field (flares and CMEs) are the principal causes of space weather (Space Studies Board, 2008). Hanuise et al. (2006) observed that a large number of solar flares are produced by a solar active region AR 10365, in which most of the flare are associated with CME have significant impact on earth. Now the question is, How the solar flare and CME affect the earth? Part of this work published in Physics Education (Lalan Prasad, Beena Bhatt and Suman Garia), 2014, 30(1), 2, 1-8. 135
As we know today we are totally depend on communication systems, without it we cannot think about modern life. The source of communication system depends on satellites and earth s ionosphere where from high frequency wave propagation possible. Both satellites and earth s ionosphere are influence by solar flares and CMEs. They may damage solar cell of satellites by solar flare protons, create plasma bubbles in earth s ionosphere, radio wave disturbance, signal scintillation, airline passenger radiation which goes through auroral region, electricity grid disruption, telecommunication cable disruption, earth current etc. Fig. 4.1 shows the effect of solar flare and CME on earth. Figure 4.1 Effect of solar flare and CME on earth. Here we briefly explained the effect of solar flare and CME on our earth. 4.2 Effect on Earth s Magnetosphere Our earth is a permanent magnet and shield around the earth is known as magnetosphere. The magnetosphere protects us from harmful radiation. The regions of magnetosphere shown in the Fig. 4.2 in terms of their magnetic field lines, originating from the northern hemisphere and terminate towards the southern hemisphere. The solar wind governs the shape of the earth's magnetosphere. Solar wind compresses its sunward side to a distance of only 6 to 10 times the radius of the earth (http://helios.gsfc.nasa.gov). Most of the solar 136
wind speed is supersonic and superalfvenic. As the solar wind impinge on earth it exerts a pressure on earth s magnetosphere which compresses earth s magnetic line of force as a result earth facing towards the sun developed a bow shock whereas on the other side also developed magnetotail (see Fig. 4.2). Figure 4.2 Earth s magnetosphere. When the solar wind strikes on earth its kinetic energy converts into thermal energy. These energy flows behind the bow shock and make magnetosheath. The area between the magnetosphere and magnetosheath is magntopause (see fig. 4.2). CME carry energetic particles, plasma and magnetic field of sun. When these CME passes near the earth the magnetic field of the sun contained by CME is combined with magnetic field of earth. As a result both magnetic fields are joined together and this joining is called magnetic reconnection. This joining is very strong when field is antiparallel. This magnetic reconnection plays a key role for disturbance in earth s atmosphere. Plasma and other energetic particle inter through this reconnection and reach the earth s atmosphere and responsible for making aurora, disturbances in ionosphere and communication media. Tsurutani and Gonzalez (1997) found that most of the intense solar storms are associated with interplanetary CMEs and shocks, passing through the earth s magnetosphere and exert large amounts of energy in the earth s magnetosphere. Hanuise et al. (2006) observed that on 29 May, solar flares associated with CME arrival at earth s 137
magnetosphere as a result solar wind pressure increased and magnetosphere became strongly compressed and the sub-solar magnetopause moved inside five earth radii. Figure 4.3 Simplified depiction of magnetic reconnection on the dayside equatorial plane of the earth s magnetosphere (modified from Mozer and Pritchett). (a) Representation of the interplanetary magnetic field and CME that passes through the earth and the sun (green) and those that are connected only with the sun or the earth (blue). (b) A close-up view of the earth s magnetosphere with the green and blue lines shown. Reconnection occurs at the point indicted where the northward-directed geomagnetic field meets the southward-directed interplanetary field. (c) Close-up view of the reconnection site on the dayside. 138
4.3 Formation of Aurora Auroras are the best visible phenomena describing the effect of solar activity on our earth. Aurora is visible almost every night near the high latitudes (Arctic and Antarctic). Aurora visible in the northern latitude is called aurora borealis or the northern lights. Similarly aurora visible in southern latitude is known as aurora australis or the southern lights, visible in Australia, South America, Antarctica and America. A typical 3 to 6 wide latitudinal banded aurora known as auroral zone observed 10 to 20 from the geomagnetic poles. GSs expand the auroral zone to lower latitudes (http://en.wikipedia. org/wiki/aurora). When a solar wind and charged particles emitted from the sun reached near the earth the magnetic field line coupled together or a magnetic reconnection takes place. The charged particle streams down on the day side of the pole as a result a day side aurora is formed. The magnetic field line stretch further back side and again coupled together as a result magnetic field line breaks and charged particles or gas from the solar storm streams along the lines and reached near the pole on the night side this is night time aurora. The charged particle collides with gas particle of atmosphere as a result a coloured pattern is formed. The colour pattern is depending on flow of charged particles and magnetic field in it. Oxygen molecules produce green and red colours while nitrogen molecules produce purplish-red and blue colours pattern. The involved energy during the aurora is almost 10 11 W (Hultquist, 2007). The chemical reaction involved to produce a green colour of aurora is following N + + O 2 NO + + O ( 1 S) By emitting a photon an oxygen atom transit to a lower excited state and create a greenyellow colour of aurora O ( 1 S) O ( 1 D) + Photon Red colour of aurora is visible due to the metastable state goes to ground state O ( 1 D) O ( 3 P) + Photon Fig. 4.4 shows the colour spectrum of aurora in different visible range. At 557.7 nm wavelength oxygen atom show a yellow-green colour and a red line spectrum at 630.0 and 636.4 nm. 139
Figure 4.4 Colour spectrum of aurora in different visible range (courtesy- Physics of the earth space environment). Here we have presented some pictures of different colours of aurora. Figure 4.5 A red and green aurora. Image taken at Hakoya Island, on October 25, 2011 by photographer Frank Olsen. 140
Figure 4.6 Aurora Borealis Northern Lights September 23, 2014, Houghton Michigan Upper Peninsula 10:00 pm to 12:00 am EDT. Figure 4.7 Aurora Borealis Northern Lights, Houghton Michigan Upper Peninsula August 28, 2014. 141
Figure 4.8 Aurora Australis as captured by NASA s image satellite, overlaid onto NASA s satellite-based Blue Marble image. 4.4 Effect on Ionosphere Ionosphere is the outermost layer of earth s atmosphere. It consists of several layers at different heights. At the day time it divided into D, E, F1 and F2 layer with different densities of ionization and at night F1 and F2 layer combined together and form a single layer F. Fig. 4.9 represents the schematic picture of earth s ionospheric layer at different altitude verses their electron density. Figure 4.9 Earth s ionosphere. 142
Each layer has its own properties, the existence and number of layers change daily under the influence of the sun. During the day, the ionosphere is heavily ionized by the sun. During the night hours the cosmic rays dominates because there is no ionization caused by the sun (which has set below the horizon). Thus, there is a daily cycle associated with the ionizations. In addition to the daily fluctuations, activity by the sun can cause dramatic sudden changes to the ionosphere. When energy from a solar flare or other disturbance reaches the earth, the ionosphere becomes suddenly more ionized. Thus, changing the density and location of layers and free electrons in the ionosphere has a strong influence on the propagation of radio signals. Fig. 4.10 shows the ionic composition of ionosphere. Figure 4.10 The composition of ionosphere as observed during the day at mid-latitudes for low solar activity. The effects of solar flare on the earth s ionosphere have been studied from many decades (Thome et al. 1971; Mitra 1974; Donnelly, 1976; Pro lss 2004; Thomson et al. 2004; Mannucci et al. 2005; Tsurutani et al., 2005; Zhang et al. 2005; Dmitriev et al. 2006; Tsurutani et al. 2009). The solar X-ray flux and EUV radiation during the process of solar flare eruption reached the earth and can increase the ionization of ionosphere at different heights, generally known as sudden ionospheric disturbances (SIDs). According to Mendillo et al. (1974) and Davies (1980) SIDs recorded as sudden enhancements of total electron 143
content (SITEC). A X-class solar flare on 14 July whose intensity is 5.7 increased the total electron contents (TEC) about 5 TECU corresponds to about 7% increase above the background of 69 TECU (1 TECU = 1012 electrons/cm 2 ) (Zhang et al., 2002a; Liu et al., 2004; Tsurutani et al., 2005). Dmitriev et al. (2006) reported that the ion density of ionosphere in the day-side is increased up to 80% due to flare associated X-ray emission at 600 km altitude of ionosphere during the a pre-storm period. Zhang et al. (2002) investigate the effect of X5.7/3B solar flare on ionosphere that occurred at 10:03 UT on 14 July 2000, using the With Global Positioning System (GPS) observations. They found that during the flare event the dayside TEC values were increased, which could 5 TECU. Tsurutani et al. (2005) and Zhang and Xiao (2005) investigated the effect of solar flare class X17/4B on 28 October 2003 and found about 25 TECU and 5 TECU enhancement. A new technique GPS network data is used for the effect of solar flare on ionosphere. Edward et al. (2002) used this technique to find the TEC. Liu (2004, 2006) studied the solar flare response to ionosphere using GPS technique and found that increase in TEC is due to the flare class. Sahai et al. (2006) observed the low-latitude regions in Brazil and found that on 28 October 2003, during the intense flare, EUV radiation increase the ionization and resulting the TEC enhancement about 25 TECU. Solar flare EUV photons can increase the TEC up to 30% within 5 min (Tsurutani et al. 2009). Figure 4.11 Systems affected by the ionosphere (Courtesy - effect of space weather on telecommunication). 144
4.5 Effect on Communication When energy from a solar flare or other disturbance reaches the earth, the ionosphere becomes suddenly more ionized. The X-ray flux during solar flare increased the ionization of lower D-region. The ionization of D-layer is due to the Lyman-α radiation (121.6 nm) from the sun, ionizing the nitric oxide (NO) molecules at the day time (Raulin et al., 2010). At the night time the ionospheric D-layer is disappeared and reflection of wave takes place through the E-layer of ionosphere. Therefore the reflection coefficient of ionosphere varies from day to night. It is the free electrons in the ionosphere that have a strong influence on the propagation of radio signals. Figure 4.12 VLF reflections through ionosphere at the day and night time. (Courtesy - http://sidstation.loudet.org/ionosphere-en.xhtml). Radio frequencies of very long wavelength (Very Low Frequency or VLF ) bounce or reflect off these free electrons in the ionosphere thus, conveniently for us, allowing radio communication over the horizon and around our curved earth. The strength of the received radio signal changes according to how much ionization has occurred and from which level of the ionosphere the VLF wave has bounced. The propagation of radio frequency (RF) signal is affected by the ionosphere (cannon 1994a; Cannon 1994b). The ionosphere, an area of the atmosphere which extends from ~80 to 145
~1000km, can significantly affect the propagation of radio frequency (RF) signals which pass through it or are reflected by it (Cannon, 1994a; Cannon, 1994b). In 1849 Barlow found that during the 8 th solar cycle in 1847 a telegraph system shows an anomalous current frequently flowing through the wire of the telegraph and the galvanometer exhibit a right swing and left swing during the day and night time respectively. The X- ray burst during the solar flare ionized the D-layer causes the SIDs (Papagiannis, 1972). Pant (1993) studied the effect of solar flare and found that sudden phase anomalies are produced in VLF signals, recorded at Nainital (India) during 1977. A one day power failure was occurred due to major GSs in March 1989 (Czech et al. 1992). The disturbance in telecommunication cable (L4) in Chicago to west coast due to a solar storm found in August 1972 (Anderson et al., 1974; Boteler and Van Beek, 1999). Bala et al. (2002) analyzed the four year data of solar burst and found that it cause the potential problem in wireless. McRae and Thomson (2004) found the effect of C-class flare on ionospheric D-layer observed by VLF radio wave propagation. Nita et al. (2004) found that the radio receiver show a noise during the solar burst. De et al. (2008) investigate the sudden enhancement at the frequencies 1, 3, 6, 9 and 12 khz from Agartala (Latitude, 23 N) in the Integrated Field Intensity of Sferics (IFIS) throughout the time of solar flares occurred during July, 2004. They also found that at 16.3 khz the transmitted signals (VTX1) influenced by solar flares in India, recorded in Kolkata. Interference in radar system during the World War II is caused by the solar radio bursts (Hey, 1946). During the solar storm a noise level is found in wireless system (Bala et al., 2002; Nita et al., 2002). We have examined the statistical properties of solar bursts from the point of view of their potential impact on wireless systems, in particular cell-phone base stations. A space weather center reported that when a radio bursts exceed ~1000 sfu it may double the noise. There are a number of space weather forecasting programs around the world, among them the space weather prediction Center at NOAA in the US (http://www. swpc.noaa.gov/) and the Ionospheric Prediction Service (IPS) in Australia (http://www. ips.gov.au/). 146
4.6 Effect on Satellites As we discussed in our previous chapter that CME create GSs near the magnetosphere of earths. CME drive GSs can damage our satellites on geosynchronous orbits. Generally the satellites are at high orbits. The satellites become highly charged and create electromagnetic interference when a high energy charge particles or solar storms strike the satellites. As a result the electronic components of satellites can damage and satellites are failed to operate. These charging are two types: surface and internal charging. A low energy electrons (<100keV) creates a surface charging which interact with surface material as a result a potential difference can established causing a electrostatic discharge. Whereas high energy electrons (>100keV) creates surface charging which interact with penetrate into the spacecraft equipment. In 2003, around 46 failures of spacecraft occurred during the GSs (http://en.wikipedia.org/). According to the severe space weather events- A workshop report that the two Canadian telecommunications satellites feel outage during a period of enhanced energetic electron fluxes at geosynchronous orbit. Report said that a satellite named Telesat s Anik E1, provides communication services in Canada was disabled to deliver news to 100 newspapers and 450 radio stations for about 7 hours. Spacecrafts will experience an anomaly during a super-storm leading to an outage of hours to days (Extreme space weather: impacts on engineered systems and infrastructure). During the period 1994-1999 spacecraft insurance company estimated that over $500,000,000 in insurance claims due to on-orbit failures related to space weather (NOAA / Space Weather Prediction Center). According to space weather center that during a GSs an increased in atmospheric heating is occurred as a result an increased drag is experienced by the spacecraft in LEO. In 1989, thousands of space objects were lost their orbit due to major GSs and also a LEO satellite lost over 30 kilometers of altitude. Ryden et al. (2008) reported that a UK-built satellite Giove-A shows the various consequences due to a solar storm together with two SEP events in December 2006. Odenwald et al. (2006) found 10 anomalies for every satellite on the bases of Carrington event. The navigation services provider satellites in MEO orbit experiences a much higher radiation than the satellite in GEO orbit (Shprits et al., 2011). 147
Table 4.1 Losses and Outage of Satellites (courtesy - Extreme space weather: impacts on engineered systems and infrastructure). 148
4.7 Effect on Electric Grid CMEs carry magnetic field of sun and when this magnetic fields move near the conductor such as a wire, a geomagnetically induced current (GIC) is produced in the conductor. The GIC is a direct current (DC). The main cause of GICs is the interaction of the geomagnetic field with the magnetic field carried by CMEs and magnetized solar wind. These GICs is the main cause of disturbance in power grid. Within the electric power system, GICs can cause transformers to operate in their nonlinear saturation range during half of the AC cycle. The consequence of half-cycle saturation includes distortions of the voltage pattern (reflected in the existence of harmonics to the primary frequency), heating within the transformers, or voltage-to-current phase shifts expressed as reactive power consumption in the system (Carolus et al., 2013). The most famous GIC event occurred in Hydro-Quebec power plant in Canada on March 13, 1989, the electrical supply was cut off to over 6 million people for 9 hours due to a huge geomagnetic storm (Kappenman and Albertson, 1990). Figure 4.13 Geomagnetic effects on power grid. 4.8 Effect on Gas Pipelines As we know gas pipelines are constructed by steels and coated by corrosion resistance coatings. The liquid or gases stored in it are under high pressure. For minimizing corrosions cathodic protection is used by keeping the negative potential with respect to 149
the ground. GIC cause swings in the pipe-to-soil potential and increase the rate of corrosion during major GSs (Gummow, 2002). 4.9 Effect on Human Body The energetic particles can pass through the human body and causing biochemical damage. Due to the radiation risk increase the possibility of occurrence of cancer and some other deceases. Astronauts are mostly affected by this if they are not well protected. 4.10 Satellite Used For Space Weather Service NASA established the number of spacecraft in earth orbit as well as in orbits around the sun at 1 AU. NASA space missions track solar disturbances from their sources on the sun, follow their propagation through the heliosphere (i.e. interplanetary space) and measure their impacts at earth. Fig. 4.14 represents the various satellites by NASA. The satellites use a combination of remote sensing observations of the sun and direct in situ measurements of the solar wind. The earth-orbiting spacecraft take critical measurements of space weather effects in earth s magnetosphere and ionosphere. In addition, numerous ground-based observatories provide data for characterizing space weather conditions and effects. Figure 4.14 Missions collecting heliophysics data. (Source - O. C. St. Cyr, NASA-GSFC, Current Space Weather Services, presentation to the space weather workshop, May 22, 2008). 150