The high-latitude ionosphere and its effects on radio propagation

Cover......Page 1
Half-title......Page 3
Series-title......Page 5
Title......Page 7
Copyright......Page 8
Contents......Page 9
Dedication......Page 18
Preface......Page 19
1.1.1 The ionosphere and radio-wave propagation......Page 23
1.1.2 Why the ionosphere is so different at high latitude......Page 24
1.2.1 Nomenclature......Page 26
1.2.2 Hydrostatic equilibrium in the atmosphere......Page 27
1.2.3 The exosphere......Page 29
Sources......Page 30
Transport......Page 31
Major species......Page 32
Minor species......Page 33
1.3.1 Introduction......Page 35
1.3.2 The Chapman production function......Page 37
1.3.3 Principles of chemical recombination......Page 40
Diffusion......Page 42
1.4.1 Introduction......Page 45
Aeronomy......Page 48
Sporadic-E......Page 49
Aeronomy......Page 53
Diurnal behavior......Page 57
Radio absorption......Page 58
The peak of the F2 layer......Page 59
The protonosphere......Page 60
The phenomena......Page 61
Winds......Page 65
1.4.6 The effects of the sunspot cycle......Page 66
1.4.7 The F-region ionospheric storm......Page 68
1.5.3 The effect of a magnetic field......Page 70
1.5.5 Currents......Page 72
1.6.1 Introduction......Page 74
1.6.2 Theory......Page 75
1.6.4 The literature......Page 79
1.4 The main ionospheric layers......Page 80
1.6 Acoustic-gravity waves and traveling ionospheric disturbances......Page 81
Conference reports......Page 82
2.2.1 The geomagnetic field......Page 83
2.2.2 The solar wind......Page 85
2.2.3 The magnetopause......Page 91
2.2.4 The magnetosheath and the shock......Page 93
2.2.6 The magnetotail......Page 94
2.3.1 Principal particle populations......Page 95
2.3.2 The plasmasphere......Page 96
2.3.4 Trapped particles......Page 100
2.3.5 The ring current......Page 106
2.3.6 Birkeland currents......Page 107
2.4.1 Circulation patterns......Page 108
2.4.2 Field merging......Page 112
2.4.3 Magnetospheric electric fields......Page 113
2.4.4 The dynamics of the plasmasphere......Page 114
2.5.1 Introduction......Page 115
2.5.2 The classical magnetic storm and the Dst index......Page 116
2.5.3 Magnetic bays at high latitude; the auroral electrojet......Page 117
2.5.4 Magnetic indices......Page 118
2.5.5 Great magnetic storms and a case history......Page 122
The aurora, magnetosphere, and solar wind......Page 123
Electric-power distribution......Page 124
Micropulsations......Page 125
Instabilities......Page 126
2.6.1 Electrons......Page 127
2.6.2 Bremsstrahlung X-rays......Page 128
2.6.3 Protons......Page 129
2.2 The magnetosphere......Page 131
2.5 Magnetic storms......Page 132
Books......Page 133
Conference reports......Page 134
3.2.1 Basics of line-of-sight propagation in vacuo......Page 135
3.2.2 Principles of radar......Page 138
A simple propagating wave......Page 140
Propagation in a lossy medium......Page 141
Conductivity......Page 142
3.2.4 Interactions between radio waves and matter......Page 143
3.3.1 The refractivity of the neutral atmosphere......Page 144
3.3.2 Terrain effects......Page 146
3.3.3 Noise and interference......Page 149
The Appleton equation......Page 162
Polarization......Page 163
Reflection at vertical incidence......Page 166
3.4.3 Relations between oblique and vertical incidence......Page 167
3.4.4 Trans-ionospheric propagation......Page 169
Phase effects......Page 170
The Faraday effect......Page 171
Absorption......Page 173
Diffraction by a thin screen of weak irregularities and the concept of the angular spectrum......Page 174
Fresnel-zone effects......Page 176
Indices and simple statistics of scintillation......Page 179
Reflection at a boundary......Page 181
Sub-ionospheric propagation at ELF and VLF......Page 185
3.4.7 Whistlers......Page 189
3.5.1 Coherent scatter......Page 191
3.5.3 Incoherent scatter......Page 193
3.6 HF-propagation-prediction programs......Page 196
3.7 Summary......Page 197
Section 3.3......Page 198
Section 3.4......Page 199
Section 3.5......Page 200
Section 3.6......Page 201
General reading......Page 202
4.2.1 Ionosondes......Page 203
Capabilities and limitations......Page 208
4.2.2 Coherent oblique-incidence radio-sounding systems......Page 209
Basic principles......Page 210
Types of oblique sounders currently in use......Page 212
HF radars......Page 224
4.2.4 D-region absorption measurements......Page 225
The URSI A1a and A1b methods......Page 226
The URSI A2 method......Page 228
Imaging riometry......Page 230
URSI A3a and A3b methods......Page 231
4.2.5 Ionospheric modification by HF transmitters......Page 232
Basic principles......Page 233
Capabilities and limitations of ionospheric-modification techniques......Page 236
4.3.2 Basic principles of operation and current deployment of radio-beacon experiments......Page 237
4.3.3 Topside sounders......Page 238
4.4.1 HF spaced-receiver and Doppler systems......Page 239
4.4.2 The HF Doppler technique......Page 241
4.5 Summary......Page 242
Section 4.2......Page 243
Section 4.3......Page 246
5.1.1 Introduction......Page 249
5.1.2 Circulation patterns......Page 250
The tongue......Page 256
The UT effect......Page 257
5.2.2 The effect of the polar cusps......Page 259
5.2.3 The polar wind......Page 261
5.2.4 The F layer in and near the auroral oval......Page 262
5.3.1 Introduction......Page 264
Patches......Page 266
Blobs......Page 267
Distribution and occurrence......Page 271
The period and depth of fading......Page 274
Spectrum......Page 278
Direct measurements......Page 279
Modeling......Page 280
5.4.1 Introduction......Page 282
Observations......Page 283
A summary of principal properties (northern hemisphere)......Page 285
Formulae for variations with time and magnetic activity......Page 287
Orientation......Page 291
Electron precipitation and the poleward edge......Page 292
5.4.4 Motions of individual troughs......Page 293
The main trough caused by plasma decay......Page 295
Other mechanisms......Page 296
5.5 Troughs and holes at high latitude......Page 298
5.6 Summary and implications......Page 302
5.2 Behaviour of the F region at high latitude......Page 303
5.3 Irregularities of the F region at high latitude......Page 304
5.4 The main trough......Page 305
5.5 Troughs and holes at high latitude......Page 306
6.1 Introduction......Page 307
6.2.1 The auroral zone and the auroral oval......Page 308
6.2.2 Models of the oval......Page 310
6.3.2 The distribution and intensity of the luminous aurora......Page 313
6.3.4 Ionospheric effects......Page 324
The E region......Page 325
X-rays......Page 326
6.3.5 The outer precipitation zone......Page 327
6.4.2 The substorm in the aurora......Page 330
6.4.3 Ionospheric aspects of the substorm......Page 333
6.4.4 Substorm currents......Page 334
6.4.5 The substorm in the magnetosphere......Page 337
Behavior in the tail......Page 338
Various theories......Page 340
The magnetic power of the solar wind......Page 341
The influence of Bz on triggering......Page 342
6.4.7 Relations between the storm and the substorm......Page 343
6.5.1 Introduction......Page 344
6.5.4 The disturbed auroral E layer......Page 345
6.5.5 Auroral radar......Page 348
Observing geometry and occurrence......Page 350
6.5.6 Auroral infrasonic waves......Page 352
6.5.7 The generation of acoustic gravity waves......Page 353
6.6 Summary and implications......Page 354
6.2 Statistical distribution of the aurora......Page 355
6.4 The substorm......Page 356
6.5 The E region at high latitude......Page 357
Conference reports......Page 358
7.1 Introduction......Page 359
7.2.1 Introduction – history and technique......Page 361
7.2.2 Typical auroral-absorption events and their temporal and spatial properties......Page 362
Sharp-onset and spike events at night......Page 363
Daytime spike events......Page 367
Slowly varying events and pulsations......Page 369
Relativistic electron-precipitation events......Page 370
Latitude and longitude distributions......Page 372
The spatial extent......Page 373
The onset and main event in the night sector......Page 376
Motions on the global scale......Page 381
The drift of the pre-onset bay......Page 383
The relation between the bay and the onset......Page 385
Co-rotation......Page 386
A relation to HF radio propagation......Page 387
Calculation of Q(1)......Page 389
The log-normal distribution......Page 391
7.2.6 The wider geophysical significance of auroral absorption events......Page 393
Incoming electron fluxes......Page 395
The onset and dynamics of the substorm......Page 399
Conjugate behavior......Page 401
7.3.1 Introduction......Page 404
Occurrence and duration......Page 406
Variation from month to month......Page 409
7.3.3 The relation to solar flares and radio emissions......Page 411
Effects in interplanetary space......Page 412
Effects in the magnetosphere......Page 414
Midday recovery......Page 417
Upper-atmosphere ionization during a proton event......Page 420
Day–night variation and twilight effects......Page 422
Effects on the neutral-species composition......Page 427
7.4 Coherent scatter and the summer mesopheric echo......Page 428
7.5 Summary and implications......Page 431
7.2 Auroral radio absorption......Page 433
7.3 The polar cap event......Page 436
7.4 Coherent scatter and the polar mesosphere summer echo......Page 437
8.1 Introduction......Page 439
8.2 ELF and VLF propagation......Page 441
8.3 LF and MF propagation......Page 451
8.4.1 Tests carried out between Alaska and Scandinavia on fixed frequencies......Page 461
HF trans-polar propagation data for the maximum of sunspot cycle 19......Page 463
The College–Stanford circuit (basically a mid-latitude path, D=3500 km)......Page 470
The College–Boston circuit (tangential to the auroral oval, D=5300 km)......Page 471
The College–Kiruna circuit (trans-polar, D=5300 km)......Page 472
College–Kjeller and Thule–Kjeller propagation-path analysis (SSN=38.3–80.2)......Page 474
8.4.4 College–Kiruna absorption studies at fixed frequencies......Page 479
The strong PCA event (SSN=155.8)......Page 490
The weak PCA event of 13 May 1960 (SSN=117.0)......Page 491
Thule–College path......Page 495
Auroral-E modes......Page 497
Other winter modes......Page 498
Off-path modes......Page 499
The Andøya–College path (D=5000 km)......Page 500
8.4.7 Other results from HF high-latitude studies from c.1956–1969......Page 501
Auroral-E ionization effects......Page 502
NGC modes......Page 503
Possible ducted modes......Page 511
8.4.8 Doppler and fading effects on HF high-latitude propagation paths......Page 514
8.5 VHF/UHF and microwave propagation......Page 551
8.6 Summary......Page 553
Section 8.1......Page 554
Section 8.3......Page 555
Section 8.4......Page 556
Section 8.5......Page 557
9.1 Introduction......Page 559
9.2.2 Current high-latitude models......Page 560
9.2.3 Validation of ionospheric models......Page 567
Validation of ELF/VLF prediction......Page 568
Validation of HF prediction......Page 569
A description of the PENEX......Page 575
Specific results of the PENEX......Page 580
The Wales–Rock Springs, Pennsylvania path......Page 581
Auroral ovals and DMSP images applied to the PENEX......Page 587
9.4 Recent efforts at validation of ionospheric models......Page 590
9.5.1 Early attempts......Page 594
9.5.2 Mitigation using solar–terrestrial data......Page 595
9.5.3 Adaptive HF techniques......Page 596
9.5.4 Realtime channel evaluation......Page 602
9.5.5 Recent advances in assessment of HF high-latitude propagation channel......Page 608
9.6.1 Large bearing errors on HF high-latitude paths......Page 613
9.6.2 Effects of substorms on auroral and subauroral HF paths......Page 615
9.6.3 Use of GPS/TEC data to investigate HF auroral propagation......Page 616
9.7 Summary and discussion......Page 619
Section 9.2......Page 629
Section 9.4......Page 631
Section 9.6......Page 632
Appendix: some books for general reading......Page 634
Index......Page 635