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Characteristics of CMEs Resulting in Extreme SEP Events

Characteristics of CMEs Resulting in Extreme SEP Events. Nat Gopalswamy NASA/GSFC nat.gopalswamy@nasa.gov. LWS Extreme Space Weather Events 2014 Workshop June 9-11 LASP Boulder CO. Two Data Sets. Major eruptions of cycle 24 (≥ M5.0) – 69 flares

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Characteristics of CMEs Resulting in Extreme SEP Events

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  1. Characteristics of CMEs Resulting in Extreme SEP Events Nat GopalswamyNASA/GSFC nat.gopalswamy@nasa.gov LWS Extreme Space Weather Events 2014 Workshop June 9-11 LASP Boulder CO

  2. Two Data Sets • Major eruptions of cycle 24 (≥ M5.0) – 69 flares • Large SEP Events (10 pfu in the >10 MeV Channel) – 31 events

  3. Major Flares of Cycle 24

  4. 16 Major Eruptions with SEPs • Examined Connectivity, Speed, and Ambient conditions • 11 had poor connectivity (longitude or latitude) • 3 had speeds lower than typical GLE CMEs • Only 3 well-connected high-speed events that are potential GLE candidates • The 2012 May 17 eruption indeed has a GLE • 2011 August 9 CME was narrower than usual • 2011 August 4 CME tenuous corona

  5. Profile of the 2012 May17 GLE SOHO/LASCO/C2 GLE #71 18.6% M5.1 Flare May 17, 2012 01:48 UT 3.57 Rs UT Weak flare (M5.1) Energetic CME (2000 km/s) Direct measurement of CME height at particle release : 2.3 Rs Shock was already present since 1:32 UT 8 min for acceleration STEREO A @W115 from Earth Nobeyama 17 GHz N11W76 STEREO A/COR1 01:40 – 2.3 Rs

  6. Tenuous Corona: High VA? weak type II

  7. 22 Non-SEP Major Eruptions from GLE Longitudes • 22/59 Events West of E15 • 8 eruptions had no SEP increase: <V> 930 km/s; Also out side of W20-W80 • 7 had minor SEP events (< 10 pfu). <V> 1373 km/s (range 873 -1773 km/s) • 4 with low elevated background (<4 pfu) <V> 1171 km/s • 3 with high elevated background (>10 pfu) • Low speed seems to be the main factor in these events

  8. SEP Events with Weaker Eruptions (<M5.0) • 15 large SEP events (out of 31 SEP events) • 5 from behind the west limb (flare size unknown) • 10 SEP events with truly weak flares: ranging from C1.2 to M3.7 (2 are filament eruption events (C-class flares)) • <V> ~1724 km/s (only 26% smaller than the SEP CMEs with ≥M5 flares) • 2011 March 07 (M3.7) CME had a speed of 2660 km/s, but source at N39W58 • Importance of CME speed rather than flare size

  9. Eastern Eruptions • 24 eastern events (East of E15) • Three had large SEP events at Earth • Examine STEREO-Behind (STB) SEP data • STB was located at E82 (2010 November 6) to E114 (2013 November 8)

  10. Eastern Eruptions… • 5 CMEs without SEP events <V> 864 km/s (419 to 1587 km/s) • 5 CMEs with elevated background (low speed) • 4 with Ip ≤60 pfu • 10 CMEs with V>2000 km/s • 4 with elevated background • 1 jet like • 4 with Ip >1000 pfu • 1 with Ip ~20 pfu • Longitudinal connectivity is important

  11. Super Event from Behind the East Limb ~5000 pfu ~10 pfu

  12. Backside Events • Importance of longitudinal connectivity

  13. 2012/07/23 Extreme Event

  14. V = 3121 km/s V = 2287 km/s Latitudinal Connectivity important for GLE events

  15. Some Higher-latitude GLEs

  16. 1998 Aug 24 [SOHO Data Gap] N35E09 Polar coronal holes present to the north of the eruption region: improved connectivity B0 ~+7.01 deg  N28 even before deflection

  17. 19980824 GLE No White-light Observation of the CME, but observed in situ (ACE, Wind) CH CME deflection by Coronal Hole towards the equator ICME at 1 AU  deflection towards the equator

  18. Pseudo streamer deflection?

  19. Summary • CME speed, latlon connectivity, and favorable ambient conditions all need to be satisfied for the acceleration of highest energy particles

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