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Comparative Analysis of the 2020 November 29 Solar Energetic Particle Event Observed by Parker Solar Probe

Lario, D. and Richardson, I. G. and Palmerio, E. and Lugaz, N. and Bale, S. D. and Stevens, M. L. and Cohen, C. M. S. and Giacalone, J. and Mitchell, D. G. and Szabo, A. and Nieves-Chinchilla, T. and Wilson, L. B., III and Christian, E. R. and Hill, M. E. and McComas, D. J. and McNutt, R. L., Jr. and Schwadron, N. A. and Wiedenbeck, M. E. (2021) Comparative Analysis of the 2020 November 29 Solar Energetic Particle Event Observed by Parker Solar Probe. Astrophysical Journal, 920 (2). Art. No. 123. ISSN 0004-637X. doi:10.3847/1538-4357/ac157f.

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We analyze two specific features of the intense solar energetic particle (SEP) event observed by Parker Solar Probe (PSP) between 2020 November 29 and 2020 December 2. The interplanetary counterpart of the coronal mass ejection (CME) on 2020 November 29 that generated the SEP event (hereafter ICME-2) arrived at PSP (located at 0.8 au from the Sun) on 2020 December 1. ICME-2 was preceded by the passage of an interplanetary shock at 18:35 UT on 2020 November 30 (hereafter S2), that in turn was preceded by another ICME (i.e., ICME-1) observed in situ on 2020 November 30. The two interesting features of this SEP event at PSP are the following: First, the presence of the intervening ICME-1 affected the evolution of the ≲8 MeV proton intensity-time profiles resulting in the observation of inverted energy spectra throughout the passage of ICME-1. Second, the sheath region preceding ICME-2 was characterized by weak magnetic fields compared to those measured immediately after the passage of the shock S2 and during the passage of ICME-2. Comparison with prior SEP events measured at 1 au but with similar characteristics indicates that (1) low-energy particles accelerated by S2 were excluded from propagating throughout ICME-1, and (2) the low magnetic fields measured in the sheath of ICME-2 resulted from the properties of the upstream solar wind encountered by ICME-2 that was propagated into the sheath, whereas the energy density of the high-energy particles in the sheath did not play a dominant role in the formation of these low magnetic fields.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemIS⊙IS data and visualization tools ItemNASA Space Physics Data Facility ItemData ItemACE Science Center
Lario, D.0000-0002-3176-8704
Richardson, I. G.0000-0002-3855-3634
Palmerio, E.0000-0001-6590-3479
Lugaz, N.0000-0002-1890-6156
Bale, S. D.0000-0002-1989-3596
Stevens, M. L.0000-0002-7728-0085
Cohen, C. M. S.0000-0002-0978-8127
Giacalone, J.0000-0002-0850-4233
Mitchell, D. G.0000-0003-1960-2119
Szabo, A.0000-0003-3255-9071
Nieves-Chinchilla, T.0000-0003-0565-4890
Wilson, L. B., III0000-0002-4313-1970
Christian, E. R.0000-0003-2134-3937
Hill, M. E.0000-0002-5674-4936
McComas, D. J.0000-0001-6160-1158
McNutt, R. L., Jr.0000-0002-4722-9166
Schwadron, N. A.0000-0002-3737-9283
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:© 2021. The American Astronomical Society. Received 2021 June 17; revised 2021 July 10; accepted 2021 July 15; published 2021 October 21. D.L. and I.G.R. acknowledge support from NASA Living With a Star (LWS) programs NNH17ZDA001N-LWS and NNH19ZDA001N-LWS and the Goddard Space Flight Center Internal Scientist Funding Model (competitive work package) program. I.G.R. also acknowledges support from the ACE mission. E.P. acknowledges the NASA LWS Jack Eddy Postdoctoral Fellowship Program, administered by UCAR's Cooperative Programs for the Advancement of Earth System Science (CPAESS) under award no. NNX16AK22G. C.M.S.C., J.G., D.G.M., E.R.C., M.E.H., D.J.M, R.L.M., N.A.S., and M.E.W. were supported as a part of the Integrated Science Investigations of the Sun on NASAs Parker Solar Probe mission, under contract NNN06AA01C. The IS⊙IS data and visualization tools are available to the community at : We acknowledge the NASA Parker Solar Probe mission team and the SWEAP team led by J.C. Kasper, the IS⊙IS team led by D.J. McComas, and the FIELDS team led by S.D. Bale, for the use of PSP data. The data used in this paper can be downloaded from,, and Search mode data during the Bastille Day event were provided by R.M. Skoug (private communication). Parker Solar Probe was designed, built, and is now operated by The Johns Hopkins University Applied Physics Laboratory as part of NASA's LWS program (contract NNN06AA01C). Support from the LWS management and technical team has played a critical role in the success of the Parker Solar Probe mission. We acknowledge all of the science instrument teams for making their data used in this paper available.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Goddard Space Flight CenterUNSPECIFIED
NASA Postdoctoral ProgramNNX16AK22G
Subject Keywords:Solar energetic particles; Interplanetary shocks; Solar coronal mass ejections; Interplanetary magnetic fields
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Solar energetic particles (1491); Interplanetary shocks (829); Solar coronal mass ejections (310); Interplanetary magnetic fields (824)
Record Number:CaltechAUTHORS:20211115-235912766
Persistent URL:
Official Citation:D. Lario et al 2021 ApJ 920 123
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111882
Deposited By: Tony Diaz
Deposited On:16 Nov 2021 17:27
Last Modified:16 Nov 2021 17:27

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