Detection of small magnetic flux ropes from the third and fourth Parker Solar Probe encounters

¹ Center for Space Plasma and Aeronomic Research (CSPAR), The University of Alabama in Huntsville, Huntsville, AL 35805, USA
e-mail: lz0009@uah.edu
² Department of Space Science, The University of Alabama in Huntsville, Huntsville, AL 35899, USA
³ National Institute for Astrophysics, Astrophysical Observatory of Torino Via Osservatorio 20, 10025 Pino Torinese, Italy
⁴ Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
⁵ Smithsonian Astrophysical Observatory, Cambridge, MA 02138, USA
⁶ Physics Department, University of California, Berkeley, CA 94720-7300, USA
⁷ Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA
⁸ The Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK
⁹ School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, UK
¹⁰ LPC2E, CNRS and University of Orléans, Orléans, France
¹¹ School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
¹² Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
¹³ Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
¹⁴ Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
¹⁵ Department of Planetary Sciences, University of Arizona, Tucson, AZ 85719, USA
¹⁶ Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA

Received: 30 August 2020
Accepted: 2 October 2020

Abstract

Context. Aims. We systematically search for magnetic flux rope structures in the solar wind to within the closest distance to the Sun of ~0.13 AU, using data from the third and fourth orbits of the Parker Solar Probe.

Methods. We extended our previous magnetic helicity-based technique of identifying magnetic flux rope structures. The method was improved upon to incorporate the azimuthal flow, which becomes larger as the spacecraft approaches the Sun.

Results. A total of 21 and 34 magnetic flux ropes are identified during the third (21-day period) and fourth (17-day period) orbits of the Parker Solar Probe, respectively. We provide a statistical analysis of the identified structures, including their relation to the streamer belt and heliospheric current sheet crossing.