1. N. Gopalswamy, H. Xie, S. Akiyama, P. Mäkelä, S. Yashiro, I. Usoskin
Heliocentric Distance of CMEs at the Time of Energetic Particle Release: GLE Events of Solar Cycle 23
N. Gopalswamy, H. Xie, S. Akiyama, P. Mäkelä, S. Yashiro, I. Usoskin
32nd ICRC Beijing 2011 August 16

2. Motivation & Approach
Test shock acceleration: Where is the CME when GLE particles are released?
Metric type II bursts – earliest indicators of shocks
Flare & CME start simultaneously (CSHKP)
CME acceleration profile same as HXR profile
CME speed max = SXR flare Max
All 16 GLEs of cycle 23 have good CME data
Limitation: Only C2 data (first appearance >2.5 Rs)
Major issue: How to extrapolate CME height to SPR time
Cross-check for 2 events (1 MLSO, 1 LASCO/C1)
CME Height at GLE release: 1.7 – 7.6 Rs

3. Extrapolations 3 Events: CME appeared before SPR Time
4 events: CME appeared 2 -4 min after SPR Time
CME speed matured, so extrapolation has minimal error
Remaining 9 events: try 4 different methods of quadratic extrapolation (constant acceleration), assume flare onset = CME onset, assume CME pre-eruption height = 1.25 Rs

4. Particle Release after CME Appearance: No major extrapolation
CME: (5.63) Rs at 02:30 UT
GLE SPR at 02:32 UT
W117
Shock
compression
V = 2712 km/s; a = ms-2
CME height at 02:32 UT = 5.99 Rs
3 events like this
(GLE ## 61, 62, 66)

5. 2001/11/04 GLE CME: 2.67 Rs at 16:25 SPR time: 16:57
Spherical expansion case
ad = – 63.4 m/s/s  7.59 Rs
CME: 2.67 Rs at 16:25
SPR time: 16:57
Extrapolate by 32 min
N06W18
Linear extrapolation at 1846 km/s  CME height at SPR: 7.76 Rs

6. 2003/10/29 GLE ad = -146.5 m/s/s  4.14 Rs CME: 2.92 Rs at 20:54
SPR time: 21:01
Extrapolate by 7 min
S19W09
Linear extrapolation at 2049 km/s  CME height at SPR: 4.34 Rs

7. SPR Just before the CME Appearance
N14W25
CME: 3.02 Rs (3.32 Rs) at 9:54
SPR 09:52 Extrapolate by 2 min
Linear extrapolation at km/s  CME height at SPR: 2.84 Rs
Four events like this (## 55, 63, 67, 69)

8. 2001/12/26 GLE N08W54 CME: 3.84 (4.72) Rs at 05:30 SPR time: 05:27
Extrapolate by 3 min
N08W54
Linear extrapolation at 1779 km/s  CME height at SPR: 4.26 Rs

9. 1997/11/06 GLE LASCO/C1 Data Available 1.45 Rs
CME: 5.18 (5.75) Rs at 12:11
SPR time: 12:07
Extrapolate by 4 min
S18W63
Linear extrapolation at 1726km/s  CME height at SPR: 5.15 Rs

10. 1997/11/07 LASCO/C1 LASCO/C1 images at 11:54:34 (1.45 Rs)
And 11:56:53 (1.88 Rs)
Deprojected: 1.61 Rs & 2.09 Rs
SPR 12:07 UT
Extrapolate from 11:57 to 12:07
CME height at SPR = 4.14 Rs
From LASCO/C2: 5.15 Rs
From Flare acceleration: 3.48 Rs
Overall uncertainty: 1.67 Rs
CME Height at Type II Onset
Expected <1.61 Rs
Extrapolate to 11:53
H = 1.57 Rs vs Rs
LASCO/C1

11. 2003/11/02 GLE MLSO Data Available 1.67 Rs
CME: 3.27 (3.75) Rs at 17:30
SPR time: 17:27
Extrapolate by 3 min
S18W59
Linear extrapolation at 2981 km/s  CME height at SPR: 2.98 Rs

12. 2003/11/02 CME with GLE 17:19 1.67 Rs 17:22 1.93 Rs 17:25 2.39 Rs
MLSO 1411 km/s
3.27 Rs
6.00 Rs
14.03 Rs
LASCO 2598 km/s

13. Cross-checking SPR time between the last MLSO image (2.39 Rs) and
first SOHO image (3.27 Rs)
CME height at SPR between
2.75 and 3.75 Rs (Deprojected)
Use combined kinematics
to get the
CME height at SPR time as 3.02 Rs
CME height at type II onset
from MLSO data is 1.18 Rs
(constant local speed).
1.28 Rs using LASCO data
G: 3.02 Rs
3.27 Rs
II: 1.28 Rs

14. Events with CME Appearance Close (2-4 min) to SPR or before SPR
GLE#
First App UT
dist (DP) Rs
SPR
CME Dist
@SPR (Rs)
CME
SPR - Accel
1997/11/06
12:11
5.18 (5.75)
12:07
5.15
3.48
2001/04/18
02:30
4.94 (5.63)
02:32
5.99
------
2001/11/04
16:25
2.67 (2.72)
16:57
7.59
9.52
2001/12/16
05:30
3.84 (4.72)
05:27
4.26
2.44
2003/10/29
20:54
2.92 (2.95)
21:01
4.34
4.61
2003/11/02
17:30
3.27 (3.75)
17:27
2.98**
3.43*
2005/01/17
17:32
3.02 (3.32)
2.84
2.94
Average
4.74
4.40
Correct value from MLSO Data: 3.02 Rs  error = 13.6%* and 1.3%**
Average CME Height at Solar Particle Release: 3.86 Rs [1.7 – 7.6]
Well-connected events: 3.08 Rs; Poorly connected: 4.87 Rs

15. Other Events: Extrapolation Needed
First appearance time and height (<H> = 4.4 Rs, 2.5 to 6Rs)
Linear extrapolation is not valid because of the acceleration in the 2 – 3 Rs range
We do not know the CME onset time
Use Flare onset = CME onset (two aspects of the same energy release; flare arcade and CME flux rope formed by the same process; Flare decides CME width; RC flux and MC flux correlated)
Constant acceleration (also an approximation)
Case 1: a = V/Δt; Δt = Flare onset to first appearance; no H used
Case 2: a = 2ΔH/Δt2 ; ΔH= 1.25 Rs to First app. Height
Case 3: a = V2/2ΔH; no time used
Case 4: Same as case 1, but Δt = Flare onset to flare peak
Flare acceleration = CME acceleration (has observational support)

16. CME speed max at Flare peak
Gopalswamy et al., 2009
Zhang et al., 2001
CME
Speed
GOES
SXR
CME
Speed
GOES
SXR
0.4 kms-2
CME speed profile similar to the Flare soft X-ray profile
CME onset ~ Flare Onset

17. Initial Accelerations
Accelerations range from 0.5 km/s2 to 7.5 km/s2
½ ρV2 ≤ B2/8π  V ≤ VA  a ≤ VA/tA= VA2/L (Vrsnak, 2008)
VA = 1500 km/s; L ~175,000 km  a ≤ 13 kms-2

18. CME Height at Type II Onset & SPR

19. Summary
CME initial acceleration is in the range 0.5 to 7.5 km/s2, consistent with theoretical expectations
Shocks form when the CME drivers are at a heliocentric distance of ~1.5 Rs (metric type II)
GLE particles are released when the CME reaches a heliocentric distance of ~3.9 Rs
Particle release when CMEs are at a lower height (3.0 Rs compared to 4.9 Rs for poorly connected events)
Independent verification possible for 2 events that had inner coronal observations

20. 2010/06/13 fp = 150 MHz  np =2.8x108 cm-3
CME starts at 5:34 at 1.13 Rs; Type II starts at 5:36 when the CME at 1.17 Rs; shock 1.19 Rs
Gopalswamy et al., 2011 ApJ

21. CME Height at Type II Onset
01/11/04
98/08/24
CME Height at Type II Onset
CME Height at GLE Onset

22. CME Height at Type II Onset
Number of Events
1.3
1.5
1.7
1.9
2.1
CME Height at Type II Onset [Rs]

23. CME Height at GLE Onset [Rs]
Flare Longitude – 60o