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Solar Sources of Geoeffective Disturbances

Solar Sources of Geoeffective Disturbances. N. Gopalswamy NASA/GSFC Greenbelt, MD 20771. Geoeffectiveness. Ability to significantly disturb geospace Dst < -50 SEP Ip > 10 pfu in the 10 MeV channel Arrival of plasmas, particles and electromagnetic radiation decide the lead times available

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Solar Sources of Geoeffective Disturbances

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  1. Solar Sources of Geoeffective Disturbances N. Gopalswamy NASA/GSFC Greenbelt, MD 20771 CAWSES Theme 2 Meeting, Beijing

  2. Geoeffectiveness • Ability to significantly disturb geospace • Dst < -50 • SEP Ip > 10 pfu in the 10 MeV channel • Arrival of plasmas, particles and electromagnetic radiation decide the lead times available • Narrow down the solar events for space weather forecast purposes CAWSES Theme 2 Meeting, Beijing

  3. Geoeffective Solar Events • Coronal Mass Ejections (severe geomagnetic storms, SEP events): most unpredictable • High-speed Streams (mild, but numerous geomagnetic storms) • Flares (prompt effects such as SID) CAWSES Theme 2 Meeting, Beijing

  4. What In situ Observations tell us? • CMEs bring strong magnetic fields • Number of MCs ~ number of storms with Dst < -100 nT • All IP shocks are CME-driven (ESP, SSC) • Earth in CME related flows for about a third of the time during solar max Gopalswamy et al., 2004 Adv. Space Res. CAWSES Theme 2 Meeting, Beijing

  5. TRANSIENT Flows at Earth 1 Shock only 4 MC Only (slow) 2 shock + sheath 3 shock+Sheath+MC Earth is embedded within one or the other of the above CME-related flows for ~ 35% Time during solar maxima and ~ 10% of the time during solar minima (Cliver et al. 2003) CAWSES Theme 2 Meeting, Beijing

  6. Solar Wind Magnetic Field 1997 02 07 CME Luhmann et al. 1999 (schematic) % OCCURRENCE 0 5 20 40 B nT Wind Mag Clouds 1996-2003 CAWSES Theme 2 Meeting, Beijing

  7. Solar Sources of ICMEs Close to Disk Center (±30deg); Slight westward bias (Wang et al; Zhang et al) Shock + ICME Sources of IP shocks Only shock Shock+ICME Interacting with Preceding CMEs Manoharan et al. 2004 JGR CAWSES Theme 2 Meeting, Beijing

  8. CMEs REACHING THE HELIOSPHERE July 10 2000 – February 5, 2001 (7 months); Ulysses poleward of S60 ~ a tenth of the CMEs produced at the Sun seem to reach far into the heliosphere These are the ones that survive for long distances from the Sun CAWSES Theme 2 Meeting, Beijing

  9. Special Populations (1-2)% • Only a small fraction of all CMEs has significant influence on the heliosphere • Halo CMEs – responsible for large geomagnetic storms • Fast and wide CMEs responsible for accelerating electrons (radio bursts) and SEPs • Fast & Wide Western CMEs produce high levels of SEP intensity at Earth CAWSES Theme 2 Meeting, Beijing

  10. Halos are similar to other CMEs:Wait for STEREO CAWSES Theme 2 Meeting, Beijing

  11. Halo CMEs • Full halos (F) • Asymmetric Halo (A) • Partial halo (P) • The faint extension on the opposite limb may be the CME-driven shock CAWSES Theme 2 Meeting, Beijing

  12. Halo CMEs are Faster on the Average • Halo CMEs have an average speed of 1000 km/s • Likely to be geoeffective if Earth-directed and posses southward B • Likely to accelerate SEPs by driving shocks CAWSES Theme 2 Meeting, Beijing

  13. Fast and wide… (47 deg non-halo) CAWSES Theme 2 Meeting, Beijing

  14. Metric Type II IP Type II CAWSES Theme 2 Meeting, Beijing

  15. Speed, Width & Acceleration of DH CMEs <V> = 1122 km/s <W> = 104 deg <a> = -6 m/s/s - CMEs driving shocks in the near-Sun IP medium are faster and wider than regular CMEs - Tend to decelerate, probably due to coronal drag.(Gopalswamy et al., 2001 JGR ) CAWSES Theme 2 Meeting, Beijing

  16. CME Mass is also much higher <M>1.6x1016 5.0x1015 <M> ~ 1.5x1015 g for all CMEs (Vourlidas 2004) 1.5x1016 CAWSES Theme 2 Meeting, Beijing

  17. DH type II, FWFW, SEPs • Overall good correlation because of physical relation (CMEshockparticles) • DH is largest in number (Eastern Events included) • Minor differences due to other parameters like Alfven speed • Too many flares CAWSES Theme 2 Meeting, Beijing

  18. Problem Areas • Halo CMEs without Geomagnetic Storms (Proper characterization; orientation of the magnetic field?) • Fast and wide CMEs without particle acceleration (property of the ambient medium?) Use radio data (All large SEP events are associated with IP type II) CAWSES Theme 2 Meeting, Beijing

  19. Working Group: Solar Sources of Geomagnetic Activity Main Topics 1. Solar sources: Coronal Mass Ejections, Coronal Holes, Large-scale Magnetic structures and boundaries, Polar magnetic fields 2. Structure of the heliosphere and interplanetary transport of solar eruptions 3. Solar energetic ions and electrons 4. Geospace response to solar events • Objectives • To understand how solar events • such as CMEs and high speed streams • impact the geospace • - investigation of the underlying science • development of prediction/forecast • models and necessary tools The Project Team N. Gopalswamy (USA, Chair) B. V. Jackson (USA) V. Obridko (Russia) A. Prigancova (Slovakia) B. Schmieder (France) K. Shibasaki (Japan) D. Webb (USA, IAU Rep. ) S. T. Wu (USA) M. Kojima (Japan) M. Zhang (China) …. Meetings Preliminary meeting in China (before IAU Symposium Sep11-12 2004) Large meeting in 2005 (during the SCOSTEP Symposium) WG formed during the ISCS meeting in Slovakia, June 2003 CAWSES Theme 2 Meeting, Beijing

  20. CAWSES Campaign(March 29-April 4, 2004) Participants – Solar SOHO/LASCO (N. Gopalswamy) HeI 10830 (J. Burkepile) H-alpha (B. Schmieder, Haimin Wang) ISOON (D. Neidig) Microwave (Shibasaki) IPS (Manoharan, Tokumaru) SXI (D. Biesecker) Metric (M. Akioka)Decametric (M. Kaiser, N. Gopalswamy) CME list (11 CMEs) Flares http://cdaw.gsfc.nasa.gov/CAWSES What Next? CAWSES Theme 2 Meeting, Beijing

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