Ion-scale secondary flux ropes generated by magnetopause reconnection as resolved by MMS

J. P. Eastwood , T. D. Phan , P. A. Cassak , D. J. Gershman , C. Haggerty , K. Malakit , M. A. Shay , R. Mistry , M. Øieroset , C. T. Russell , J. A. Slavin , M. R. Argall , L. A. Avanov , J. L. Burch , L. J. Chen , J. C. Dorelli , R. E. Ergun , B. L. Giles , Y. Khotyaintsev , B. Lavraud (1) , P. A. Lindqvist , T. E. Moore , R. Nakamura , W. Paterson , C. Pollock , R. J. Strangeway , R. B. Torbert , S. Wang

1 IRAP - Institut de recherche en astrophysique et planétologie

New Magnetospheric Multiscale (MMS) observations of small-scale (~7 ion inertial length radius) flux transfer events (FTEs) at the dayside magnetopause are reported. The 10 km MMS tetrahedron size enables their structure and properties to be calculated using a variety of multispacecraft techniques, allowing them to be identified as flux ropes, whose flux content is small (~22 kWb). The current density, calculated using plasma and magnetic field measurements independently, is found to be filamentary. Intercomparison of the plasma moments with electric and magnetic field measurements reveals structured non-frozen-in ion behavior. The data are further compared with a particle-in-cell simulation. It is concluded that these small-scale flux ropes, which are not seen to be growing, represent a distinct class of FTE which is generated on the magnetopause by secondary reconnection.

Keywords: magnetic reconnection; magnetopause; flux rope; secondary island; magnetospheric multiscale

Domains: Sciences of the Universe [physics]

J. P. Eastwood, T. D. Phan, P. A. Cassak, D. J. Gershman, C. Haggerty, et al.. Ion-scale secondary flux ropes generated by magnetopause reconnection as resolved by MMS. Geophysical Research Letters, 2016, 43, pp.4716-4724. ⟨10.1002/2016GL068747⟩. ⟨insu-03670242⟩