Electron Inflow Velocities and Reconnection Rates at Earth's Magnetopause and Magnetosheath

Electron inflow and outflow velocities during magnetic reconnection at and near the dayside magnetopause are measured using satellites from NASA's Magnetospheric Multiscale (MMS) mission. A case study is examined in detail, and three other events with similar behavior are shown, with one of them being a recently published electron‐only reconnection event in the magnetosheath. The measured inflow speeds of 200–400 km/s imply dimensionless reconnection rates of 0.05–0.25 when normalized to the relevant electron Alfvén speed, which are within the range of expectations. The outflow speeds are about 1.5–3 times the inflow speeds, which is consistent with theoretical predictions of the aspect ratio of the inner electron diffusion region. A reconnection rate of 0.04 ± 25% was obtained for the case study event using the reconnection electric field as compared to the 0.12 ± 20% rate determined from the inflow velocity.

[1]  D. Fischer,et al.  Polynomial Reconstruction of the Reconnection Magnetic Field Observed by Multiple Spacecraft , 2020, Journal of Geophysical Research: Space Physics.

[2]  T. Forbes,et al.  A New Method of 3‐D Magnetic Field Reconstruction , 2019, Geophysical Research Letters.

[3]  C. Russell,et al.  Energy Conversion and Electron Acceleration in the Magnetopause Reconnection Diffusion Region , 2019, Geophysical Research Letters.

[4]  C. Russell,et al.  Structure of the Current Sheet in the 11 July 2017 Electron Diffusion Region Event , 2019, Journal of geophysical research. Space physics.

[5]  H. Ji,et al.  The two-fluid dynamics and energetics of the asymmetric magnetic reconnection in laboratory and space plasmas , 2018, Nature Communications.

[6]  C. Russell,et al.  How Accurately Can We Measure the Reconnection Rate E M for the MMS Diffusion Region Event of 11 July 2017? , 2018, Journal of geophysical research. Space physics.

[7]  C. Russell,et al.  Electron magnetic reconnection without ion coupling in Earth’s turbulent magnetosheath , 2018, Nature.

[8]  R. Denton,et al.  Localized Oscillatory Energy Conversion in Magnetopause Reconnection , 2017, 1712.05697.

[9]  P. Cassak,et al.  Localized and Intense Energy Conversion in the Diffusion Region of Asymmetric Magnetic Reconnection , 2017, Geophysical Research Letters.

[10]  C. Russell,et al.  Electron Crescent Distributions as a Manifestation of Diamagnetic Drift in an Electron‐Scale Current Sheet: Magnetospheric Multiscale Observations Using New 7.5 ms Fast Plasma Investigation Moments , 2017, Geophysical Research Letters.

[11]  P. Lindqvist,et al.  Structure and Dissipation Characteristics of an Electron Diffusion Region Observed by MMS During a Rapid, Normal‐Incidence Magnetopause Crossing , 2017 .

[12]  C. Russell,et al.  Instability of Agyrotropic Electron Beams near the Electron Diffusion Region. , 2017, Physical review letters.

[13]  P. Lindqvist,et al.  Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations , 2017 .

[14]  R. Torbert,et al.  Motion of the MMS spacecraft relative to the magnetic reconnection structure observed on 16 October 2015 at 1307 UT , 2016 .

[15]  U. Gliese,et al.  Fast Plasma Investigation for Magnetospheric Multiscale , 2016 .

[16]  J. B. Blake,et al.  Electron-scale measurements of magnetic reconnection in space , 2016, Science.

[17]  Thomas E. Moore,et al.  Magnetospheric Multiscale Overview and Science Objectives , 2016 .

[18]  Wolfgang Baumjohann,et al.  The FIELDS Instrument Suite on MMS: Scientific Objectives, Measurements, and Data Products , 2016 .

[19]  A. Klimas New Expression for Collisionless Magnetic Reconnection Rate , 2015 .

[20]  David G. Sibeck,et al.  On the electron diffusion region in planar, asymmetric, systems , 2014 .

[21]  H. Karimabadi,et al.  Recent Evolution in the Theory of Magnetic Reconnection and Its Connection with Turbulence , 2013 .

[22]  S. Petrinec,et al.  The location of reconnection at the magnetopause: Testing the maximum magnetic shear model with THEMIS observations , 2012 .

[23]  P. Cassak,et al.  Structure of the dissipation region in fluid simulations of asymmetric magnetic reconnectiona) , 2009 .

[24]  S. Gerhardt,et al.  Experimental study of the Hall effect and electron diffusion region during magnetic reconnection in a laboratory plasma , 2008 .

[25]  D. Tsiklauri A new fast reconnection model in a collisionless regime , 2008, 0808.0143.

[26]  M. Shay,et al.  The Hall fields and fast magnetic reconnection , 2008 .

[27]  P. Cassak,et al.  Asymmetric Magnetic Reconnection: General Theory and Collisional Simulations , 2007 .

[28]  F. Mozer,et al.  Quantitative estimates of magnetic field reconnection properties from electric and magnetic field measurements , 2007 .

[29]  M. Shay,et al.  Two-scale structure of the electron dissipation region during collisionless magnetic reconnection. , 2007, Physical review letters.

[30]  P. Cassak,et al.  Catastrophe model for fast magnetic reconnection onset. , 2005, Physical review letters.

[31]  R. E. Grundy,et al.  Exact solutions for reconnective magnetic annihilation , 2000, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[32]  S. Schwartz Shock and Discontinuity Normals, Mach Numbers, and Related Parameters , 1998 .