Physics of Space Storms (eBook)

Physics of Space Storms 3
Contents 5
Preface 11
Units and Notation 17
1. Stormy Tour from the Sun to the Earth 19
1.1 Source of Space Storms: the Sun 19
1.1.1 The Sun as a star 20
1.1.2 Solar spectrum 23
1.1.3 Solar atmosphere 25
1.1.4 Rotation of the Sun 26
1.1.5 Sunspots and solar magnetism 29
1.1.6 Coronal activity 34
1.2 The Carrier to the Earth: the Solar Wind 39
1.2.1 Elements of solar wind expansion 39
1.2.2 The interplanetary magnetic field 43
1.2.3 The observed structure of the solar wind 46
1.2.4 Perturbed solar wind 47
1.3 The Magnetosphere 50
1.3.1 Formation of the Earth’s magnetosphere 50
1.3.2 The outer magnetosphere 52
1.3.3 The inner magnetosphere 55
1.3.4 Magnetospheric convection 58
1.3.5 Origins of magnetospheric plasma 62
1.3.6 Convection and electric fields 63
1.4 The Upper Atmosphere and the Ionosphere 66
1.4.1 The thermosphere and the exosphere 67
1.4.2 Structure of the ionosphere 68
1.4.3 Electric currents in the polar ionosphere 69
1.5 Space Storms Seen from the Ground 72
1.5.1 Measuring the strength of space storms 73
1.5.2 Geomagnetically induced currents 75
2. Physical Foundations 77
2.1 What is Plasma? 77
2.1.1 Debye shielding 78
2.1.2 Plasma oscillations 79
2.1.3 Gyro motion 80
2.1.4 Collisions 81
2.2 Basic Electrodynamics 82
2.2.1 Maxwell’s equations 82
2.2.2 Lorentz force 84
2.2.3 Potentials 84
2.2.4 Energy conservation 88
2.2.5 Charged particles in electromagnetic fields 89
2.3 Tools of Statistical Physics 91
2.3.1 Plasma in thermal equilibrium 91
2.3.2 Derivation of Vlasov and Boltzmann equations 93
2.3.3 Macroscopic variables 96
2.3.4 Derivation of macroscopic equations 98
2.3.5 Equations of magnetohydrodynamics 100
2.3.6 Double adiabatic theory 104
3. Single Particle Motion 107
3.1 Magnetic Drifts 107
3.2 Adiabatic Invariants 111
3.2.1 The first adiabatic invariant 111
3.2.2 Magnetic mirror and magnetic bottle 113
3.2.3 The second adiabatic invariant 114
3.2.4 Betatron and Fermi acceleration 114
3.2.5 The third adiabatic invariant 115
3.3 Motion in the Dipole Field 116
3.4 Motion Near a Current Sheet 121
3.4.1 The Harris model 122
3.4.2 Neutral sheet with a constant electric field 124
3.4.3 Current sheet with a small perpendicular magnetic field component 125
3.5 Motion in a Time-dependent Electric Field 126
3.5.1 Slow time variations 126
3.5.2 Time variations in resonance with gyro motion 126
3.5.3 High-frequency fields 127
4. Waves in Cold Plasma Approximation 130
4.1 Basic Concepts 130
4.1.1 Waves in linear media 130
4.1.2 Wave polarization 134
4.1.3 Reflection and refraction 135
4.2 RadioWave Propagation in the Ionosphere 138
4.2.1 Isotropic, lossless ionosphere 138
4.2.2 Weakly inhomogeneous ionosphere 141
4.2.3 Inclusion of collisions 145
4.2.4 Inclusion of the magnetic field 146
4.3 General Treatment of Cold Plasma Waves 147
4.3.1 Dispersion equation for cold plasma waves 147
4.3.2 Parallel propagation (. = 0) 150
4.3.3 Perpendicular propagation (. = p/2) 153
4.3.4 Propagation at arbitrary angles 154
5. Vlasov Theory 157
5.1 Properties of the Vlasov Equation 157
5.2 Landau’s Solution 159
5.3 Normal Modes in a Maxwellian Plasma 164
5.3.1 The plasma dispersion function 164
5.3.2 The Langmuir wave 165
5.3.3 The ion–acoustic wave 166
5.3.4 Macroscopic derivation of Langmuir and ion–acoustic modes 167
5.4 Physics of Landau Damping 169
5.5 Vlasov Theory in a General Equilibrium 171
5.6 Uniformly Magnetized Plasma 173
5.6.1 Perpendicular propagation (. = p/2) 175
5.6.2 Parallel propagation (. = 0) 177
5.6.3 Propagation at arbitrary angles 177
6. Magnetohydrodynamics 179
6.1 From Hydrodynamics to Conservative MHD Equations 179
6.2 Convection and Diffusion 182
6.3 Frozen-in Field Lines 184
6.4 Magnetohydrostatic Equilibrium 187
6.5 Field-aligned Currents 189
6.5.1 Force-free fields 189
6.5.2 Grad–Shafranov equation 192
6.5.3 General properties of force-free fields 193
6.5.4 FACs and the magnetosphere–ionosphere coupling 194
6.5.5 Magnetic helicity 196
6.6 Alfvén Waves 199
6.6.1 Dispersion equation of MHD waves 199
6.6.2 MHD wave modes 200
6.7 Beyond MHD 202
6.7.1 Quasi-neutral hybrid approach 203
6.7.2 Kinetic Alfvén waves 205
7. Space Plasma Instabilities 207
7.1 Beam–plasma Modes 208
7.1.1 Two-stream instability 209
7.1.2 Buneman instability 211
7.2 Macroinstabilities 212
7.2.1 Rayleigh–Taylor instability 212
7.2.2 Farley–Buneman instability 215
7.2.3 Ballooning instability 216
7.2.4 Kelvin–Helmholtz instability 218
7.2.5 Firehose and mirror instabilities 220
7.2.6 Flux tube instabilities 222
7.3 Microinstabilities 223
7.3.1 Monotonically decreasing distribution function 223
7.3.2 Multiple-peaked distributions 224
7.3.3 Ion–acoustic instability 226
7.3.4 Electrostatic ion cyclotron instability 228
7.3.5 Current-driven instabilities perpendicular to B 229
7.3.6 Electromagnetic cyclotron instabilities 231
7.3.7 Ion beam instabilities 233
8. Magnetic Reconnection 235
8.1 Basics of Reconnection 235
8.1.1 Classical MHD description of reconnection 236
8.1.2 The Sweet–Parker model 237
8.1.3 The Petschek model 239
8.1.4 Asymmetric reconnection 241
8.2 Collisionless Reconnection 243
8.2.1 The tearing mode 244
8.2.2 The collisionless tearing mode 245
8.2.3 Tearing mode or something else? 247
8.2.4 The Hall effect 248
8.3 Reconnection and Dynamo 252
8.3.1 Current generation at the magnetospheric boundary 252
8.3.2 Elements of solar dynamo theory 254
8.3.3 The kinematic a. dynamo 257
9. Plasma Radiation and Scattering 260
9.1 Simple Antennas 260
9.2 Radiation of a Moving Charge 263
9.3 Bremsstrahlung 266
9.4 Cyclotron and Synchrotron Radiation 270
9.5 Scattering from Plasma Fluctuations 273
9.6 Thomson Scattering 276
10. Transport and Diffusion in Space Plasmas 281
10.1 Particle Flux and Phase Space Density 281
10.2 Coordinates for Particle Flux Description 283
10.3 Elements of Fokker–Planck Theory 285
10.4 Quasi-Linear Diffusion Through Wave–Particle Interaction 287
10.5 Kinetic Equation with Fokker–Planck Terms 290
11. Shocks and Shock Acceleration 292
11.1 Basic Shock Formation 293
11.1.1 Steepening of continuous structures 293
11.1.2 Hydrodynamic shocks 295
11.2 Shocks in MHD 296
11.2.1 Perpendicular shocks 296
11.2.2 Oblique shocks 298
11.2.3 Rotational and tangential discontinuities 300
11.2.4 Thickness of the shock front 301
11.2.5 Collisionless shock wave structure 303
11.3 Particle Acceleration in Shock Waves 306
11.3.1 Shock drift acceleration 307
11.3.2 Diffusive shock acceleration 308
11.3.3 Shock surfing acceleration 310
12. Storms on the Sun 312
12.1 Prominences and Coronal Loops 313
12.2 Radio Storms on the Sun 315
12.2.1 Classification of radio emissions 316
12.2.2 Physical mechanisms for solar radio emissions 317
12.3 Solar Flares 320
12.3.1 Observational characteristics of solar flares 320
12.3.2 Physics of solar flares 324
12.4 Coronal Mass Ejections 327
12.4.1 CMEs near the Sun 328
12.4.2 Propagation time to 1 AU 330
12.4.3 Magnetic structure of ICMEs 331
12.5 CMEs, Flares and Particle Acceleration 333
13. Magnetospheric Storms and Substorms 336
13.1 What are Magnetic Storms and Substorms? 336
13.1.1 Storm basics 337
13.1.2 The concept of substorm 339
13.1.3 Observational signatures of substorms 339
13.2 Physics of Substorm Onset 346
13.2.1 The outside–in view 347
13.2.2 The inside–out view 352
13.2.3 External triggering of substorm expansion 355
13.2.4 Timing of substorm onset 355
13.3 Storm-Time Activity 358
13.3.1 Steady magnetospheric convection 358
13.3.2 Substorm-like activations and sawtooth Events 361
13.4 ICME–Storm Relationships 363
13.4.1 Geoeffectivity of an ICME 363
13.4.2 Different response to different drivers 365
13.5 Storms Driven by Fast Solar Wind 367
13.5.1 27-day recurrence of magnetospheric activity 367
13.5.2 Differences from ICME-driven storms 368
13.6 Energy Budgets of Storms and Substorms 370
13.6.1 Energy supply 370
13.6.2 Ring current energy 371
13.6.3 Ionospheric dissipation 373
13.6.4 Energy consumption farther in the magnetosphere 375
13.6.5 Energy transfer across the magnetopause 375
13.7 Superstorms and Polar Cap Potential Saturation 378
13.7.1 Quantification of the saturation 379
13.7.2 Hill–Siscoe formulation 379
13.7.3 The Alfv´en wing approach 381
13.7.4 Magnetosheath force balance 382
14. Storms in the Inner Magnetosphere 384
14.1 Dynamics of the Ring Current 385
14.1.1 Asymmetric structure of the ring current 385
14.1.2 Sources of the enhanced ring current 386
14.1.3 Role of substorms in storm evolution 389
14.1.4 Loss of ring current through charge exchange collisions 389
14.1.5 Pitch angle scattering by wave–particle interactions 392
14.1.6 ENA imaging of the ring current 394
14.2 Storm-Time Radiation Belts 395
14.2.1 Sources of radiation belt ions 395
14.2.2 Losses of radiation belt ions 396
14.2.3 Transport and acceleration of electrons 397
14.2.4 Electron losses 403
15. Space Storms in the Atmosphere and on the Ground 405
15.1 Coupling to the Neutral Atmosphere 405
15.1.1 Heating of the thermosphere 406
15.1.2 Solar proton events and the middle atmosphere 406
15.2 Coupling to the Surface of the Earth 407
References 410
Index 422