SM027-06
MMS Observations of Forward and Reverse Ion-scale Flux Ropes in the Plasma Sheet: Evidence for Turbulent Reconnection?

Friday, 11 December 2020: 04:20
Virtual
James A Slavin1, Wei-Jie Sun2, Qiang Hu3, Mojtaba Akhavan-Tafti2, Dogacan Su Ozturk4,5, Charles Bowers1, Gangkai Poh6, Guan Le7, San Lu8, Daniel J Gershman7, Barbara L Giles7 and James L Burch9, (1)University of Michigan Ann Arbor, Department of Climate and Space Sciences and Engineering, Ann Arbor, MI, United States, (2)University of Michigan Ann Arbor, Climate and Space Sciences and Engineering, Ann Arbor, MI, United States, (3)University of Alabama in Huntsville, Department of Space Science, Huntsville, AL, United States, (4)University of Michigan Ann Arbor, AOSS, Ann Arbor, MI, United States, (5)Jet Propulsion Laboratory, Pasadena, CA, United States, (6)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (7)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (8)University of California Los Angeles, Los Angeles, CA, United States, (9)Southwest Research Institute San Antonio, San Antonio, TX, United States
Recorded Presentation
Abstract:
MMS high-time resolution observations of the reconnection process have confirmed the close relationship between the formation of diffusion regions and the creation of ion-inertial scale flux ropes (FRs). Ion-scale FRs are observed to form as a result of reconnection at multiple X-lines in highly thinned current sheet and secondary instabilities within larger magnetic structures. However, the formation of ion-scale FRs through turbulent reconnection associated with large-amplitude magnetic fluctuations and thin current sheet formation remains less well-understood than other FR formation mechanisms. On 11 June 2017 at ~ 17:00 UTC, the MMS constellation was located near the cross-tail current sheet at XGSM ~ -22 Re and YGSM ~ - 11 Re. At the same time, the OMNI interplanetary data showed that the solar wind dynamic pressure suddenly increased from ~ 5 to 8 nPa with BZGSM ~ -7 nT. The AE also increases between 17:30 and 18:00 UTC, peaking at ~ 800 nT. At 17:01:22 UTC, all four MMS spacecraft observed what we term a “reverse” ion-scale FR moving tailward at ~ 800 km/s. Unlike the far more common “forward” FRs, which exhibit a northward-then-southward change in the L-component of the magnetic field vector in the minimum variance coordinate system as it travels tailward, the reverse FRs exhibit the opposite (or “reverse”) bi-polar BL signature (i.e. southward-then northward) with similar tailward flow speeds. The creation of reverse FR would appear to require either large-amplitude turbulent reconnection at its point of formation or a large rotation of the FR as it moves tailward. Here we report parallel analyses of MMS observations of examples of forward and reverse FRs in the plasma sheet. We also present simulation results from the Univ. of Michigan Space Weather Modelling Framework global MHD model of the 11 June 2017 reverse FR event. The simulation results predict strong velocity gradients, and quasi-turbulent stretching and twisting of the magnetic field near the location, where MMS observes the reverse FR. We will also discuss the frequency of occurrence and significance of this new population of flux ropes in the terrestrial magnetotail.
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