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Extreme Solar Eruptions: Sources and Consequences

Extreme Solar Eruptions: Sources and Consequences. Nat Gopalswamy Solar Physics Laboratory NASA/GSFC. ICTP/ISWI Workshop May 20-24, 2019. What is an Extreme Event?. Event on the tail of a distribution of interest

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Extreme Solar Eruptions: Sources and Consequences

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  1. Extreme Solar Eruptions: Sources and Consequences Nat Gopalswamy Solar Physics Laboratory NASA/GSFC ICTP/ISWI Workshop May 20-24, 2019

  2. What is an Extreme Event? • Event on the tail of a distribution of interest • An occurrence singularly unique either in the occurrence itself or in terms of its consequences • Occurrence: CME, flare (active region size, magnetic content) • Consequences: SEP events, Magnetic storms • Tail: The physics does not change

  3. What can we learn from the study of tails (caudology?) …

  4. … about the whole animal? David B. Stephenson 2005

  5. CME – Flare Relationship • Two manifestations of the energy release from magnetic regions on the Sun • Sometimes flares occur without CMEs • CMEs are always accompanied by flares (sometimes flare signatures may not be seen due to instrument sensitivity) • Big flares accompany energetic CMEs • Both CMEs and flares cause SEPs, but flare SEP events are small • Flares do not cause geomagnetic storms; CMEs do (Gosling 1993)

  6. Confined vs. Eruptive Flares • ~ 20% of ≥M5.0 flares are not accompanied by CMEs • Confined flares are hotter than eruptive ones • Both confined and eruptive flares produce hard X-ray and microwave bursts • No EUV waves found in confined flares • No upward energetic electrons (lack of metric or longer wavelength type III, type II bursts) in confined flares • No SEP events • Confined: generally a single loop • Eruptive: • associated with erupting prominence • CME, shock • type II radio burst • two - ribbon flares • Post-eruption arcade

  7. Confined Flare: No mass motion X1.5 Flare Confined flares just produce excess photons No mass motion

  8. An Eruptive Event Manifests as CME + Flare Flares have prompt effect on the ionosphere SOHO/LASCO & EIT Difference Images overlaid X1.5 Flare Shock EUV WAVE CME CMEs can result in daytime TEC increase (1-4 days later) Gosling 1993, solar flare myth JGRA 98, 18937

  9. A very weak flare A-class flare barely seen in the soft X-ray light curve Flare seen as an extended structure in soft X-ray images. The image obtained in the energy channel 0.25 – 4 keV (2 – 50 Å)

  10. 293 km/s; 15.9 m/s/s SC Oct 10 18 UT Dst min Oct 11 4UT (-130 nT) Zhang et al. 2007

  11. A Solar Eruption: CME, Flare, SEP, Shock, Radio Burst, Magnetic Storm ESP 100 3000 pfu 1689 km/s Source Location N11E12 SEP Shock Halo CME 33 h Earth Sun Type II Burst (DH –km) shock SSC Storm UN/ESA/NASA/JAXA Workshop

  12. Historical Fast Transit Events 27 23 Jul 2012 01:50 S17W141 ???? 18.6 2330 Cliver et al., 1990; Gopalswamy et al., 2005

  13. CME Source Regions Photospheric Magnetogram Chromosphere (H-alpha) A B A B A: active region B: Filament region (also bipolar, but no sunspots) Both regions have filaments along the polarity inversion line

  14. Where does the energy come from? Extrapolated field lines on TRACE 171 A coronal images b c a 2005/05/13 14:56:00 2005/05/13 15:25:56 2005/05/13 21:26:36 Actual coronal structure is “distorted” from potential field  free energy (FE) Distortion due to current J. Lorentz force JxB propels the CME Photospheric magnetogram with potential field extrapolation Free energy went into the CME kinetic energy Arcade is now almost potential (very little current J) De Rosa & Schrijver

  15. Flare Size in X-rays (1 – 8 Å) SOLRAD, GOES Data since 1969 • The corrected size of the 2003/11/03 Flare: • X34–X48, mean ~ X40 (Brodrick et al. 2005) • Carrington flare size: X42 – X48, nominal value of X45 (Cliver and Dietrich 2013) • Weibull distribution: X43.9 (100-year); X101 (1000-year) • Power law distribution: similar flare sizes: X42 and X115 • X100  1033 erg • A 1034 erg flare can occur once in 125,000 yr B A X100 M C X10 X The 4 November 2003 flare at 19:29 UT has the highest intensity of 2.8x10-3 W m-2 (X28).

  16. CME Speed and Kinetic Energy 100: 3800 km/s 1000: 4700 km/s 100: 4.4×1033 erg 1000: 9.8×1033 erg

  17. Sunspot Group Area • A 100-year AR has an area of ~7000 msh (power law) • and ~5900 msh (Weibull function) • Use a max values of 6000 msh for estimates • Max field strength ~6100 G (Livingston et al. 2006) • Max Potential energy ~ (B2/8π)A1.5 = 3.7×1036erg Maximum observed area was ~5000 msh (SC 18) in 143 yr

  18. Max. CME Speed and Kinetic Energy from AR 3.7×1036 erg 6700 ~4.2×1035 11% eff 3600 Free energy ~ PE If FE>PE, the efficiency is higher • Potential Energy = (<B>2/8π)A1.5 • A = area covered by at least 10% of the peak unsigned magnetic field strength B • <B> is the unsigned average field strength within A • Active regions that produced SEP events, magnetic clouds or magnetic storms

  19. AR Flux vs. Reconnected Flux • B = 6100 G, A = 6000 msh (6000x3.07×1016 cm2). • AR flux ΦAR is ~1.12×1024 Mx. • ΦRC = 0.79ΦAR0.98 gives • ΦRC ~2.9×1023 Mx, • KE = 0.19(ΦRC)1.87 (Gopalswamy et al. 2017 SC 23 CMEs) gives • KE = 7.7×1034erg (not the maximum) • Such events may occur once in ~6300 yr (from the KE distribution assuming power law)

  20. Peak SEP Intensity 100: 2.04×105 pfu; 1000: 1.02×106pfu

  21. Solar Cycle Variation

  22. SEP Source Regions on the Sun Confined to active region belt Western hemispheric preference

  23. CME Rate & SSN ? Inter-cycle variation between CME rate and SSN CME rate per SSN 0.02 (SC 23) vs. 0.04 (SC 24) CME occurrence rate is closely correlated with SSN

  24. Kinetic Energy ~1.5×1025 J Chicxulub Meteor: 1.1×1023 J CME Speed and Width

  25. Significant CMEs & their Consequences Cycle 23 – 24 CMEs from SOHO/LASCO Gopalswamy, 2006; 2010 m2 – Metric type II MC – Magnetic Cloud EJ – Ejecta S – Interplanetary shock GM – Geomagnetic storm Halo – Halo CMEs DH – Type II at λ 10-100 meters SEP – Solar Energetic Particles GLE – Ground Level Enhancement p<10-4 Plasma impact Energetic electrons Energetic protons

  26. Fluence >30 MeV >10 MeV

  27. Integral Fluences for Different Model Fits (in units of 1010 p cm-2)

  28. Fluence Spectra of Miyake Particle Events Scaled from 2005 January 20 GLE event • 1000-year fluences in the >10 MeV and >30 MeV ranges cover the AD774/5 and AD 992/3 events • Two-point slopes consistent with those of the known SEP events • AD774/5 and AD 992/3 events are consequences of SEP events • The 2012 July 23 Event shows that extreme events can occur in weak sunspot cycles 1956/2/23 1972/8/4 Miyake et al. 2013; Mekhaldi et al. 2015; Usoskin 2017; Gopalswamy et al. 2016

  29. Out of the Ecliptic B from CMEs • Normal Parker-spiral field does not have a Bz component • CMEs with flux rope structure (magnetic clouds) naturally produce the Bz component • Magnetic field draping in the shock sheath can also cause Bz (Gosling & McComas, 1987; Tsurutani & Gonzalez, 1988) • Corotating interaction regions and fast wind have Alfven waves that represent Bz, but the magnitude is relatively small

  30. Geomagnetic Storm and CME parameters Gopalswamy 2008 Dst = – 0.01VBz – 32 nT Dst [nT] The high correlation suggests That V and Bz are the most Important parameters ( - Bz is absolutely necessary) V and Bz in the IP medium are related to the CME speed and magnetic content VMCBz [104 nT•km/s] Carrington Event: VBz = 1.6 105 nT•km/s V = 2000 km/s, Dst = -1650 nT  Bz = -81 nT

  31. Origin of V and B Dst = – 0.01VBz – 32 nT Solar Wind speed CIR Speed CME speed Alfven waves CIR: Amplified Alfven waves ICME: Sheath & Flux rope Active Region Free energy Heliospheric Mag Field Active Region Mag Field

  32. Magnetic Storms • The Weibull distribution fits all the data points. • A100-year event has a size of -603 nT, consistent with the March 1989 event • A 1000-year event has a size of -845 nT, consistent with some estimates of the Carrington storm: • -1600 nT (Tsurutani et al. 2003) • -850 nT (Siscoe 2006) • -1160 nT (Gonzalez et al. 2011) • -900 nT (Cliver and Dietrich 2013) • The empirical relation, • Dst = -0.01VBz – 32 nT • can explain –1160 nT if V = 2000 km/s and Bz = -78 nT • Using • Bt = 0.06 VICME - 13.58 nT (Gopalswamy et al. 2017) • And • |Bz| = 0.74 Bt, it is possible to get Bt =106 nT and Bz = -78 nT

  33. The Carrington record may not be due to Ring current? Kumar et al. 2015 JGR

  34. Summary of 100-year and 1000-year Event Sizes

  35. Summary • Assuming extreme events to be events on the tails of cumulative distributions, we estimated one-in-100 and one-in-1000 yr sizes • Weibull function used as the baseline in extrapolating the distributions to estimate the 100-year and 1000-year event sizes; Power-law distributions appear to yield overestimates • The >30 MeV fluence of a 1000-year event is in the range (1-5)×1010 p cm-2 • Consistent with the historical extreme event such as the Carrington event, the AD 774/75 event, the AD 994/95 event, and the recent 2012 July 23 backside event • The simple relation Dst = -0.01VBz – 32 nT is adequate to estimate extreme storms including the Carrington storm

  36. 100 MeV protons penetrate to the stratosphere and can destroy ozone. GeV particles can affect airplane crew/passengers in polar routes 1 MeV proton 10 MeV proton Middle Atmosphere 100 MeV proton Protons penetrating Earth’s Atmosphere 100 Thermosphere Mesopause 80 Mesosphere 60 Stratopause Altitude (km) 40 OZONE Stratosphere 20 Tropopause 1 GeV proton Troposphere 0 Courtesy: C. Jackman

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