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Radial Evolution of a CIR: Observations From a Nearly Radially Aligned Event Between Parker Solar Probe and STEREO-A

Allen, R. C. and Ho, G. C. and Mason, G. M. and Li, G. and Jian, L. K. and Vines, S. K. and Schwadron, N. A. and Joyce, C. J. and Bale, S. D. and Bonnell, J. W. and Case, A. W. and Christian, E. R. and Cohen, C. M. S. and Desai, M. I. and Filwett, R. and Goetz, K. and Harvey, P. R. and Hill, M. E. and Kasper, J. C. and Korreck, K. E. and Lario, D. and Larson, D. and Livi, R. and MacDowall, R. J. and Malaspina, D. M. and McComas, D. J. and McNutt, R. and Mitchell, D. G. and Paulson, K. W. and Pulupa, M. and Raouafi, N. and Stevens, M. L. and Whittlesey, P. L. and Wiedenbeck, M. (2021) Radial Evolution of a CIR: Observations From a Nearly Radially Aligned Event Between Parker Solar Probe and STEREO-A. Geophysical Research Letters, 48 (3). Art. No. e2020GL091376. ISSN 0094-8276.

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The addition of Parker Solar Probe (PSP) to the Heliophysics System Observatory has allowed for the unprecedented ability to study Corotating Interaction Regions (CIRs) at multiple radial distances without significant temporal/longitudinal variations. On September 19, 2019, PSP observed a CIR at ∼0.5 au when it was nearly radially aligned with the Solar Terrestrial Relations Observatory‐Ahead (STEREO‐A) spacecraft at ∼1 au, allowing for an unambiguous assessment of the radial evolution of a single CIR. Bulk plasma and magnetic field signatures of the CIR evolve in a fashion characteristic to previous observations; however, the suprathermal ions are enhanced over a larger longitudinal range at PSP than at STEREO‐A, although at much lower intensities. The longitudinal spread appears to be largely a consequence of magnetic field line topology at CIRs between the compressed slow solar wind upstream and high‐speed stream following the CIR, underscoring the importance of the large‐scale topology of these structures.

Item Type:Article
Related URLs:
URLURL TypeDescription
https://sppgway.jhuapl.eduRelated ItemParker Solar Probe data ItemSTEREO SEPT data
https://stereo-ssc.nascom.nasa.govRelated ItemSTEREO magnetic field and plasma data
https://cdaweb.gsfc.nasa.govRelated ItemWind data
Allen, R. C.0000-0003-2079-5683
Ho, G. C.0000-0003-1093-2066
Mason, G. M.0000-0003-2169-9618
Li, G.0000-0001-9313-251X
Jian, L. K.0000-0002-6849-5527
Vines, S. K.0000-0002-7515-3285
Schwadron, N. A.0000-0002-3737-9283
Joyce, C. J.0000-0002-3841-5020
Bale, S. D.0000-0002-1989-3596
Case, A. W.0000-0002-3520-4041
Christian, E. R.0000-0003-2134-3937
Cohen, C. M. S.0000-0002-0978-8127
Desai, M. I.0000-0002-7318-6008
Filwett, R.0000-0002-5497-7867
Goetz, K.0000-0003-0420-3633
Harvey, P. R.0000-0002-6938-0166
Hill, M. E.0000-0002-5674-4936
Kasper, J. C.0000-0002-7077-930X
Korreck, K. E.0000-0001-6095-2490
Lario, D.0000-0002-3176-8704
Larson, D.0000-0001-5030-6030
Livi, R.0000-0002-0396-0547
MacDowall, R. J.0000-0003-3112-4201
Malaspina, D. M.0000-0003-1191-1558
McComas, D. J.0000-0002-9745-3502
McNutt, R.0000-0002-4722-9166
Mitchell, D. G.0000-0003-1960-2119
Paulson, K. W.0000-0002-5699-090X
Pulupa, M.0000-0002-1573-7457
Raouafi, N.0000-0003-2409-3742
Stevens, M. L.0000-0002-7728-0085
Whittlesey, P. L.0000-0002-7287-5098
Wiedenbeck, M.0000-0002-2825-3128
Additional Information:© 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Issue Online: 01 February 2021; Version of Record online: 01 February 2021; Accepted manuscript online: 14 January 2021; Manuscript accepted: 05 January 2021; Manuscript revised: 28 December 2020; Manuscript received: 21 October 2020. This work was supported by the NASA’s Parker Solar Probe Mission, contract NNN06AA01C. Data Availability Statement: Parker Solar Probe data can be accessed from The STEREO SEPT data are available at, and STEREO magnetic field and plasma data can be found at the STEREO Science Center: Wind data are available at This event is taken from the catalog by Allen et al. (2020c).
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:CIRs; Parker Solar Probe; solar wind; STEREO; suprathermal ions
Issue or Number:3
Record Number:CaltechAUTHORS:20210120-094033556
Persistent URL:
Official Citation:Allen, R. C., Ho, G. C., Mason, G. M., Li, G., Jian, L. K., Vines, S. K., et al. (2021). Radial evolution of a CIR: Observations from a nearly radially aligned event between Parker Solar Probe and STEREO‐A. Geophysical Research Letters, 48, e2020GL091376.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107587
Deposited By: Tony Diaz
Deposited On:20 Jan 2021 18:02
Last Modified:03 Feb 2021 17:08

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