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Variability of Solar Eruptions During Cycle 23

Variability of Solar Eruptions During Cycle 23. N. Gopalswamy (NASA/GSFC) 2 nd Elmau CME Meeting WG-A Presentation Friday, Feb 6, 203. In this work…. CME rate (daily rate averaged over Carrington Rotation – CRs 1904 to 1984: 1996-2001) Metric type II bursts

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Variability of Solar Eruptions During Cycle 23

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  1. Variability of Solar Eruptions During Cycle 23 N. Gopalswamy (NASA/GSFC) 2nd Elmau CME Meeting WG-A Presentation Friday, Feb 6, 203

  2. In this work… • CME rate (daily rate averaged over Carrington Rotation – CRs 1904 to 1984: 1996-2001) • Metric type II bursts • Decameter-Hectometric (DH) Type II bursts • Special Populations • Fast and Wide Frontside Western CMEs • Large SEPs (10 pfu in the > 10 MeV range) • DH type II bursts • Halo CMEs

  3. Data Sources • CMEs form the SOHO/LASCO catalog: http://cdaw.gsfc.nasa.gov/CME-list • Metric type II from Solar Geophysical Data supplemented by web sites of various observatories • DH type II bursts from the Wind/WAVES type II catalog: http://www-lep.gsfc.nasa.gov/waves • SEPs from NOAA’s GOES proton Data; also assembled in the LWS/CDAW page: http://cdaw.gsfc.nasa.gov/LWS

  4. All CMEs (1996-2001) Td = Down time in each CR Tu = Up time during each CR Rmax = Max no. of CMEs per day during a CR Robs = # CMEs in the CR/Tu Upper limit to rate: (Tu Robs + TdRmax)/27.34. Lower limit: Robs/27.34  Averaged over Carrington Rotations (CRs)  CMEs/day increased from 1 every other day to > 5 per day SOHO Data Gap

  5. Variability of Mean Speed • Mean speed increases from Min to max by a factor of ~2 •  Speed variation smoother • than the CME rate • CR 1970 (2000/11/23) low CME rate, speed remains high • Influence of super-active ARs • Large scale structure of B? (Ivanov & Obridko 2000)

  6. Speed Distributionannual & Semi-annual Avg

  7. Metric Type II Bursts

  8. DH Type II Bursts (1-14 MHz) Speed is important

  9. Properties of radio-rich CMEs -CMEs driving shocks in the near-Sun IP medium are faster and wider than regular CMEs - Note that 88/132 CMEs were halo CMEs -Tend to decelerate, probably due to coronal drag. (Gopalswamy et al., 2001 JGR 106, 29217)

  10. CME Speed & Source Longitude of Solar Energetic Particle Events major: I >10 pfu; minor:1 < I < 10 pfu • SEP CMEs are very fast (> 900km/s) • They occur west of E45 • 98% of SEP-producing CMEs had W > 100 deg • Almost all events were associated with DH type II bursts

  11. DH type II, FWFW, SEPs • Overall Good correlation because of physical relation • DH is largest in number (Eastern Events included) • Minor differences due to other parameters like Alfven speed

  12. Fast-wide CMEs: Potentially Geoeffective (SEP)

  13. Halo CMEs • Frontside halo CMEs are potentially geoeffective – they cause geomagnetic storms if any of the substructures contains southward B component.

  14. Summary • There is an order of magnitude increase in CME rate from min (0.5/day) to max (5/day) • The mean CME speed also increases from min (250 km/s) to max (500 km/s) • Metric type II number tracks CME rate; velocity may be important but secondary • DH type II bursts: Velocity & CME rate important • DH type II, SEPs are due to fast and wide frontside CMEs • Only 1-2% of CMEs are important for SEPs

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