1. Karl-Ludwig Klein & Rositsa Miteva
Solar Energetic Particle Events and their Parent Activity : a Re-assessment of Statistical Relationships
Karl-Ludwig Klein
& Rositsa Miteva
(F Meudon)
Universités
P&M Curie, Diderot
Collaborators: Olga Malandraki & Garreth Dorrian, National Observatory of Athens, Greece

2. Correlation SEP intensity - solar activity Past work, motivation of this study
Intensities of protons>10 MeV in SEP events correlate with CME speed (VCME) and SXR peak flux (ISXR)
All correlations are noisy:
Kahler (2001, JGR 106, 20947): pre-event
particle intensity (=seed population for
CME shock acceleration ?)
Garcia (2004, Spa Wea 2, S0202):
combination of SXR parameters
(ISXR, EM, duration)
Problem: SEP measured in a single point,
after a long IP travel (scattering, … ):
IP transport, magnetic connection
Present study: influence of the IMF configuration ?
Kahler 2001 JGR 106, 20947

3. SEP events and IMF configuration The IP path of SEP
Standard picture: Parker spiral IMF connection
Alternative: ICME  SEP released onto field lines of an earlier CME whose front has reached the Earth
Present study:
Identification of ICMEs: from Richardson & Cane catalogue (2010 SP 264, 189)
SEPs: all events (GOES; Cane et al JGR(A) 115, A08101) with M or X class flares, western solar hemisphere.
GOES protons (15-40 MeV) from ONERA/Toulouse database (81 events),
ACE/EPAM electrons keV (96).
Earth
From Zurbuchen & Richardson 2006 SSR

4. SEP events and IMF configuration The IP path of SEP
Result (Miteva et al SP, in press): the IMF configuration of SEP events
20% of SEP events associated with well-defined western flares (M, X) within ICMEs (« ICME events »),
about 50 % within standard solar wind (« SoWi events »),
rest in an intermediate IMF configuration
Transient IMF configurations important even for SEP with activity in W hemisphere !
Fraction of ICME events increases with importance of associated solar activity:
14-18% SEP associated with M class,
29% SEP associated with X class;
Masson et al A&A: 7/10 GLEs (>X5 class) in the vicinity of an ICME
Earth
From Zurbuchen & Richardson 2006 SSR

5. J(SEP)-ISXR-VCME correlation SEPs in the solar wind (SoWi events) and in ICMEs
All SEP events:
J(p)/VCME= 0.630.05
J(e)/VCME= 0.530.07
J(p)/ISXR = 0.590.07
J(e)/ISXR = 0.400.08
ICME events:
J(SEP) /VCME unchanged
J(p)/ISXR = 0.670.13
J(e)/ISXR = 0.730.10
SoWi events:
J(p)/ISXR = 0.360.13
J(e)/ISXR = 0.120.11

6. J(SEP)-ISXR correlation SEPs in the solar wind (SoWi events) and in ICMEs
Result:
J(SEP)/VCME correlation independent of IMF configuration.
J(SEP)/ISXR correlation very weak in SoWi events, both for e and p.
Why is the J(SEP)/ISXR correlation so much weaker in SoWi events than in ICME events (and in the entire event sample) ?
What distinguishes ICME events from SoWi events ?
SEP transport in two different IMF configurations.

7. J(SEP)-ISXR correlation
Blurring of the correlation by particle transport
Time profile at injection (source surface)
Any relationship J(SEP)ISXRb is blurred by SEP transport in the turbulent IMF
log(intensity)
Time profile at s/c (1 AU)
time
log(intensity)
time
Does varying IP transport affect SEP more in the solar wind than in ICMEs ?
Measure: fastest rise time during the rise of the SEP profile
Protons: yes (earlier work: Tranquille et al. 1987; Torsti et al. 2004; Malandraki et al. 2005)
Electrons: no

8. J(SEP)-ISXR correlation SEPs in the solar wind (SoWi events) and in ICMEs
Why is the J(SEP)/ISXR correlation so much weaker in SoWi events than in ICME events (and in the entire event sample) ?
What distinguishes ICME events from SoWi events ?
SEP transport in two different IMF configurations.
Connection between solar activity (flare) and observer (s/c).

9. J(SEP)-ISXR correlation SEPs in the solar wind (SoWi events) and in ICMEs
Why is the J(SEP)/ISXR correlation so much weaker in SoWi events than in ICME events (and in the entire event sample) ?
What distinguishes ICME events from SoWi events ?
SEP transport in two different IMF configurations.
Connection between solar activity (flare) and observer (s/c): super-radial expansion of open flux tubes in AR (Wang & Sheeley 2003 ApJ; Klein et al A&A), concentrated flux in the legs of ICMEs.. AR AR

10. J(SEP)-ISXR correlation Blurring of the correlation by the connection distance
Range of
coronal
field lines
f
Flare
f
IMF
Range of IMF lines,
width IMF
IMF through s/c
(cf. Lario et al ApJ)
The relationship J(SEP)ISXRb is blurred by
(1) differences between longitudes of the flare and the Parker spiral
(2) div. of flare-connected coronal field lines around flare direction: 0=f+f
(3) scattering of the root of the IMF around the Parker spiral: =PS+IMF

11. J(SEP)-ISXR-VCME correlation Summary and conclusion
Empirical findings
SEPs often observed in transient IMF configurations (ICMEs)
J(SEP)/VCME correlation independent of configuration (e, p alike)
J(SEP)/ISXR correlation weak/absent when SEP propagate in standard solar wind, high when in ICMEs (e, p alike)
Interpretation: a correlation between J(SEP) and ISXR is blurred by
IP particle transport: but rise time distributions of p and e behave differently
varying connection distances: not strong enough to be the exclusive interpretation
Absence of a strict J(SEP)/ISXR correlation for flare-accelerated SEP + contribution of CME shock-accelerated particles
Strong J(SEP) - ISXR correlation in ICME events consistent with a contribution of flare-acceleration (protons10 MeV, electrons  30 keV) to early SEPs if magnetic connection exists.
Necessity of a vantage point nearer to the Sun to reduce IP transport and provide a closer look at injection time profiles - Solar Orbiter.