The Physics of Space Plasmas William J. Burke 31October 2012 University of Massachusetts, Lowell Magnetic Storms

Historical background: - Dessler-Parker-Sckopke - Burton-Russell-McPherron relationships Electric fields in the inner magnetosphere: penetration, shielding and over-shielding. - Single particle approach: the Volland-Stern model - Fluid/multi-fluid approach: The Rice Convection model -Two crises:(1) too much shielding (June 1991 storm), and (2) electric field saturation (Bastille Day Storm) - Tsyganenko: Magnetic inflation and contributors to Dst -Siscoe-Hill and revised Volland-Stern models Love and Gannon: Dst movies Transmission line analogy Magnetic Storms Lecture 7

Magnetic Storms Magnetic Storms: a brief history: Alexander von Humboldt coined the term “magnetic storm” after watching aurorae and magnetic deflection over Berlin in Dec.21, Richard Carrington: witnesses white light flare August 28, 1859 followed by magnetic storm on the next day: aurorae over Havana. Kristin Birkeland: After campaign distinguished between polar elementary storms (substorms) and equatorial perturbations. Sydney Chapman: phases of magnetic storms Alex Dessler & Gene Parker: (1959) E RC   H at the Earth’s surface. Masahisa Sugiura: Dst stations and hourly index to calibrate storms Burton et al. (1975): Predict Dst from solar wind/IMF

Magnetic Storms Stormtime E-fields in Inner Magnetosphere: E-fields are the only force that can accelerate charged particles In general: Consider a charge particle with an equatorial pitch angle of 90  in the presence of a dawn-to-dusk electric field E = - . Since

Magnetic Storms The Volland-Stern single-particle model: Here we use a version of the V-S model formulated by Ejiri, JGR, 83, 4798, Consider the electric potential  (R,  ) in the magnetospheric equatorial plane as a superposition of a co-rotation and “externally imposed” potentials The corotation potential. C is a constant determined by boundary conditions and  is a fitting parameter whose physical meaning is addressed below. We will use both cylindrical (R,  and Cartesian (X GSM, Y GSM ) coordinates. Assume that E is in the dawn-dusk (+ Y GSM ) direction  B 0 R E 2  91 kV

Magnetic Storms The Volland-Stern single-particle model: At some point R S = R E L S along the dusk meridian (  =  /2) the inward pointing E C exactly cancels the outward directed E M allowing us to calculate C

Magnetic Storms The Volland-Stern single-particle model: At the stagnation point L S the potential is Since the last closed equipotential touches LS => calculate locus of this potential L A (  ) gives shape of zero-energy Alfvén boundary (ZEAB) Still don’t know what  means or how to relate E M to the interplanetary medium.

Magnetic Storms The Volland-Stern single-particle model: At the magnetopause on the dawn (L Y, 3  /2) and dusk (L Y,  /2) the potentials are approximately  PC /2 and -  PC /2, respectively. Average E across magnetosphere  1 L Y  1.5 L X

Magnetic Storms Vasyliunas (1969, 1970) Rice Convection Model: (Harel et al., JGR 1981)

Magnetic Storms Main Phase Electric fields and particles measured by CRRES

Magnetic Storms

Electric field and particle boundaries sampled by DMSP F8 and CRRES

Magnetic Storms Tsyganenko, N. A., H. J. Singer, and J. C. Kasper, Storm-time distortion of the inner magnetosphere: How severe can it get? J. Geophys. Res., 108 (A5), 1209, Magnetosphere simulation at 22:00 UT on 6 April 2000

Magnetic Storms Magnetosphere simulation at 08:00 UT on 31 March 2001

Magnetic Storms

Z Y BB BB Siscoe et al. (2002), Hill model of transpolar saturation: Comparisons with MHD simulations, JGR 107, A6, Ober et al. (2003), Testing the Hill model of transpolar potential saturation, JGR, 108, (A12), Model validation with F13 & F15

Magnetic Storms Ober et MRC: ISM Simulations with IMF B Z = -2 and -20 nT  PC =  I  S / (  I +  S )  S =  P SW 0.33 (nPa) /   I =  0 +  G V B T Sin 2 (  /2)

Magnetic Storms Love, J. J., and J. L. Gannon (2010), Movie ‐ maps of low ‐ latitude magnetic storm disturbance, Space Weather, 8, S06001, doi: /2009SW

Magnetic Storms November 2003 storm

Magnetic Storms

Electric field Scaling: Kelley et al. (2003), Penetration of the solar wind electric field into the magnetosphere/ionosphere system, GRL., 30(4), compared electric measured with the Jicamarca ISR fields with the Y component of IEF (VB Z ). Found the electric field in the equatorial ionosphere is one 15 th of the electric field in the solar wind It seemed useful to compare  VS with IEF Y

Magnetic Storms

Huang, C. Y. and W. J. Burke (2004) Transient sheets of field aligned currents observed by DMSP during the main phase of a magnetic superstorm, JGR, 109, A06303.

Magnetic Storms Transmission line model “ Measured” Poynting Flux

Aurorae and High-Latitude Electrodynamics Region 1 = 10 6 A Region 2 = 0 A Region 1 = 10 6 A Region 2 = 3  10 5 A Nopper and Carovillano, GRL 699, 1978 Wolf, R. A., Effects of Ionospheric Conductivity on Convective Flow of Plasma in the Magnetosphere, JGR, 75, 4677, 1970.