Interplanetary transport of near- relativistic solar electron events - - PowerPoint PPT Presentation

Interplanetary transport of near- relativistic solar electron events under different solar wind conditions.

Daniel Pacheco1, R. Gómez-Herrero2, N. Agueda1, A. Aran1

• 1. Dept. de Física Quantica i Astrofísica, Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB), Spain
• 2. Space Research Group, Universidad de Álcala, Spain

OUTLINE

• 1. Description of the two studied events and motivation
• 2. Modelling the observed SEP events.
• 3. Results
• 4. Conclusions

Events 2014 August 1

Klassen et al. (2016)

➢

Detected by both STEREOs

➢

Well-connected

➢

Impulsive nature

➢

Stable solar wind conditions

➢

No type II radio burst associated

Selection Criteria

➢

The angular peak intensity distribution does not show the usual Gaussian distribution.

➢

They propose as an explanation of their results a “fingered” spatial peak intensity distribution of SEP events at 1 AU.

➢

This could also be is related to different transport conditions. Klassen et al. (2016)

Events 2014 August 1

➢

To study if these observations can also be explained by different transport conditions in the interplanetary medium. Goal of our study

Interplanetary transport model

➢

S t a t i c s

• u

r c e a t 2 s

• l

a r r a d i i

➢

I d e a l P a r k e r s p i r a l

➢

F

• c

u s i n g e f f e c t

➢

P i t c h

• a

n g l e s c a t t e r i n g ( c

• n

v e c t i

• n

, d e c e l e r a t i

• n

)

➢

N

• p

e r p e n d i c u l a r d i f u s s i

• n

➢

λr = c

• n

s t .

➢ Differential intensities of electrons at 1 AU as a

f u n c t i

• n
• f

t i m e , p i t c h a n g l e a n d e n e r g y .

➢ For an instantaneus injection at the Sun.

Focused transport equation

Agueda et al. (2012)

Roelof (1969)

Simulation results

Inversion

➢ Release time history ➢ Interplanetary transport contiditons

Agueda et al. (2008,2014)

➢ Inversion approach ➢ Angular response of the detectors included ➢ 25 values of the radial mean free path (0.05-2.77 AU) ➢ Deconvolution of the effects of interplanetary transport ➢ Each channel fitted separately ➢ Best possible release time history and λr inferred

SEPInversion software Procedure Results

Results Event I Results Event II

STEREO A STEREO A STEREO B STEREO B

Different profiles for each FOV More anisotropic PADs Similar profiles for each FOV Very isotropic PADs

Event I, STA Best connected! Event I, STB Event II, STA Event II, STB Best connected!

Injection profiles & transport conditions

Conclusions

➔ Release is almost simultaneous for both s/c, short in

duration (<10 min) and higher for the best connected s/c.

➔ The event starts first for the s/c located inside the less

diffusive flux tube.

➔ The characteristics of the transport are different in the

different solar wind regimes.

➔ The low particle intensities observed by STB at 1 AU can

be explained by more turbulent conditions (lower value of the mean-free path).

This work was performed under the Spanish Project AYA2013-42614-P.

Contact: dpacheco@ub.edu

Thank you for your attention!

Acknowledgements