Earth Magnetism - A Guided Tour through Magnetic Fields
A wonder of such nature I experienced as a child of 4 or 5 years, when my
father showed me a compass. That this needle behaved in such a determined
way did not at all fit into the nature of events, which could find a place in the
unconscious world of concepts (effect connected with direct 'touch'). I can
still remember--or at least I believe I can remember--that this experience
made a deep and lasting impression upon me. Something deeply hidden had
to be behind things.
- Albert Einstein
Preface xv
Acknowledgments xxi
1 Nature's Magnetism 1
1.1 Finding the Fields ....................... 1
1.2 Historical Tour Markers .................... 2
1.2.1 Compass Origin ..................... 2
1.2.2 Global Explorations ................... 3
1.2.3 Geomagnetism Patriarchs ................. 5
Gilbert ........................ 5
Halley ........................ 7
Faraday ....................... 5
Gauss ........................ 7
Maxwell ....................... 7
Chapman ...................... 11
1.3 Local Language Dictionary .................. 7
1.3.1 Earth Fields, Steady and Changing ............ 11
1.3.2 Forces at Work ..................... 13
1.3.3 Measuring Scales .................... 15
1.3.4 Locating the Fields .................... 17
1.3.5 Nature's Basic Particles ................. 18
Atoms ........................ 18
Molecules ...................... 19
Ions and Current ................... 20
1.4 Our Tour of the Fields ..................... 22
2 Vistas of Lives in the Fields 25
2.1 Fields Making a Difference .................. 25
2.1.1 Travel and Exploration .................. 25
2.1.2 Magnetic Rocks ..................... 30
2.1.3 Prehistoric Fields and Continental Drift .......... 35
2.1.4 Field Mapping and Geologic Exploration .......... 37
2.1.5 Sudden Field Changes in the Crust ............ 40
2.1.6 Biomagnetism ...................... 41
2.1.7 Medicine ........................ 42
2.1.8 Magnetic Levitation (Maglev) ............... 44
2.1.9 Magnetic Fields and Technology .......... . . . 44
Destruction in Space ................. 44
Interference with Communication and Navigation .... 47
2.1.10 Field Induction Responses ................ 50
Earth Conductivity .................. 50
Electric Power Systems ................ 50
Long-Wire Communications .............. 51
Pipeline Corrosion .................. 52
2.2 Tour to the Boundaries ..................... 53
2.2.1 Establishing Significance ................. 53
Statistical Sampling .................. 54
Correlation ...................... 54
Cause and Effect ................... 54
Double Blind ..................... 55
Modeling ...................... 55
2.2.2 Magnetic Correlations .................. 55
Weather and Climate ................. 55
Human Responses to Magnetic Fields .......... 58
2.2.3 Pseudoscience, Old Wives' Tales, and Frauds ....... . 60
Magnetic Termites .................. 60
Body Magnets .................... 61
Water Improvement .................. 63
Water Witching or Divining .............. 63
Focusing of Lightning ................. 64
Bermuda Triangle and Oceanic Fields ......... 65
Earthquake Predictions ................ 66
3. Sailing the Magnetic Seas in Calm Winds
3.1 Inside Sources ......................... 70
3.2 Pole Markers .......................... 72
3.2.1 Magnetic Poles Galore .................. 72
3.2.2 IGRF Main Field Poles .................. 74
3.2.3 Geomagnetic Coordinate Poles .............. 78
3.2.4 Two Eccentric Axis Poles ................. 80
3.2.5 Locally Measured Dip Poles ............... 82
3.2.6 Satellite Evidence of Poles ................ 84
A Space of Quiet Fields .................... 86
Conducting Blanket ...................... 88
Quietly Flowing Currents ................... 90
3.5.1 A Dynamo ....................... 90
3.5.2 Solar-Quiet, Sq ..................... 92
3.5.3 Induction ........................ 93
3.5.4 Sectors ......................... 94
Umbrella for Magnetic Storms 97
4.1 Disturbances in Sight ..................... 97
4.1.1 On the Sun ....................... 97
4.1.2 In the Wind ....................... 101
4.1.3 Storms Overhead .................... 102
Earth Field Encounter ................. 102
Glamorous Display .................. 103
4.1.4 Agitation in the Fields .................. 106
Storm Fingerprints .................. 106
Storm Explanations .................. 108
Heating ....................... 111
4.1.5 Measures of Activity ................... ] 15
AE Index ...................... 115
Dst Index ...................... 115
Kp Index ...................... 115
Ap Index ...................... 117
4.1.6 Pulsations ........................ 119
Harvesting the Fields 121
5.1 Field Traces .......................... 121
5.1.1 Early Record Keeping ................. . 121
5.1.2 Modern Field Recording ................. 122
5.1.3 Do-It-Yourself Systems .................. 125
Soda-Bottle Magnetometer .............. 125
Earth-Current Pulsation Sensor ............. 127
5.2 Scientists at Work ....................... 128
5.2.1 Dipole Field Patterns ................... 128
5.2.2 Fluid Velocity at Core-Mantle Boundary .......... 128
5.2.3 Magnetotellurics ..................... 128
5.2.4 Polar Sector Currents 9 130
5.2.5 Dst Storm Index ..................... 130
5.2.6 Pulsations ........................ 131
5.3 Track and Field Records .................... 132
5.4 Space Weather Disturbance Scales .............. 134
5.5 Information Kiosk ....................... 134
5.6 Directions for Further Travel ................. 139
Download: Earth Magnetism - A Guided Tour through Magnetic Fields
scientific information about a relevant topic, magnetic fields, in a way that is
state-of-the-science, yet fun to read.
Dr. Campbell has authored several well-known books. His recent book,
Introduction to Geomagnetic Fields, is one of the most important references
in our field. He has also authored numerous articles published in scientific
journals in which his peers subject papers to critical review. In addition, na-
tional and international agencies and corporations routinely seek his advice.
Thus, Dr. Campbell is a respected leader in geophysics and space physics, not
just geomagnetism.
Dr. Campbell carries an unbridled enthusiasm for geomagnetism, which
he is willing and able to share with scientists and nonscientists alike. He
presents the state of the science in a wonderful and meaningful way. The rel-
evant principles and physics of magnetism are discussed in a complete, yet
easy-to-understand way. The Earth's main field and its origin and changes are
simply and clearly presented. Dr. Campbell discusses the effects of particles
and fields of solar, interplanetary, and near-Earth space origin on measure-
ments of the Earth's magnetic field. He presents these external currents as the
result of both normal and unusual solar emissions, including large solar flares
and coronal mass ejections spewing copious fluxes of charged particles with
their associated magnetic and electric fields. These events frequently cause
significant changes in the near-Earth space environment that have been named
magnetic storms and substorms. He presents this information with respect to
its impact on technology in space and on the ground, including telecommu-
nications, satellite operations, satellite drag, and radio propagation, and he
relates these effects to events that occur in our daily lives. He also tackles the
controversial false science as it relates to geomagnetic fields.
Dr. Campbell has accepted the difficult task of talking to all of us about
a complex and difficult-to-understand part of our environment, the magnetic
field of the Earth, and he does so with superb clarity, simplicity, and practi-
cality.
Dr. Herbert W. Kroehl
General Secretary, International Association for
Geomagnetism and Aeronomy
Download: Earth Magnetism - A Guided Tour through Magnetic Fields
father showed me a compass. That this needle behaved in such a determined
way did not at all fit into the nature of events, which could find a place in the
unconscious world of concepts (effect connected with direct 'touch'). I can
still remember--or at least I believe I can remember--that this experience
made a deep and lasting impression upon me. Something deeply hidden had
to be behind things.
- Albert Einstein
Contents
Foreword xiiiPreface xv
Acknowledgments xxi
1 Nature's Magnetism 1
1.1 Finding the Fields ....................... 1
1.2 Historical Tour Markers .................... 2
1.2.1 Compass Origin ..................... 2
1.2.2 Global Explorations ................... 3
1.2.3 Geomagnetism Patriarchs ................. 5
Gilbert ........................ 5
Halley ........................ 7
Faraday ....................... 5
Gauss ........................ 7
Maxwell ....................... 7
Chapman ...................... 11
1.3 Local Language Dictionary .................. 7
1.3.1 Earth Fields, Steady and Changing ............ 11
1.3.2 Forces at Work ..................... 13
1.3.3 Measuring Scales .................... 15
1.3.4 Locating the Fields .................... 17
1.3.5 Nature's Basic Particles ................. 18
Atoms ........................ 18
Molecules ...................... 19
Ions and Current ................... 20
1.4 Our Tour of the Fields ..................... 22
2 Vistas of Lives in the Fields 25
2.1 Fields Making a Difference .................. 25
2.1.1 Travel and Exploration .................. 25
2.1.2 Magnetic Rocks ..................... 30
2.1.3 Prehistoric Fields and Continental Drift .......... 35
2.1.4 Field Mapping and Geologic Exploration .......... 37
2.1.5 Sudden Field Changes in the Crust ............ 40
2.1.6 Biomagnetism ...................... 41
2.1.7 Medicine ........................ 42
2.1.8 Magnetic Levitation (Maglev) ............... 44
2.1.9 Magnetic Fields and Technology .......... . . . 44
Destruction in Space ................. 44
Interference with Communication and Navigation .... 47
2.1.10 Field Induction Responses ................ 50
Earth Conductivity .................. 50
Electric Power Systems ................ 50
Long-Wire Communications .............. 51
Pipeline Corrosion .................. 52
2.2 Tour to the Boundaries ..................... 53
2.2.1 Establishing Significance ................. 53
Statistical Sampling .................. 54
Correlation ...................... 54
Cause and Effect ................... 54
Double Blind ..................... 55
Modeling ...................... 55
2.2.2 Magnetic Correlations .................. 55
Weather and Climate ................. 55
Human Responses to Magnetic Fields .......... 58
2.2.3 Pseudoscience, Old Wives' Tales, and Frauds ....... . 60
Magnetic Termites .................. 60
Body Magnets .................... 61
Water Improvement .................. 63
Water Witching or Divining .............. 63
Focusing of Lightning ................. 64
Bermuda Triangle and Oceanic Fields ......... 65
Earthquake Predictions ................ 66
3. Sailing the Magnetic Seas in Calm Winds
3.1 Inside Sources ......................... 70
3.2 Pole Markers .......................... 72
3.2.1 Magnetic Poles Galore .................. 72
3.2.2 IGRF Main Field Poles .................. 74
3.2.3 Geomagnetic Coordinate Poles .............. 78
3.2.4 Two Eccentric Axis Poles ................. 80
3.2.5 Locally Measured Dip Poles ............... 82
3.2.6 Satellite Evidence of Poles ................ 84
A Space of Quiet Fields .................... 86
Conducting Blanket ...................... 88
Quietly Flowing Currents ................... 90
3.5.1 A Dynamo ....................... 90
3.5.2 Solar-Quiet, Sq ..................... 92
3.5.3 Induction ........................ 93
3.5.4 Sectors ......................... 94
Umbrella for Magnetic Storms 97
4.1 Disturbances in Sight ..................... 97
4.1.1 On the Sun ....................... 97
4.1.2 In the Wind ....................... 101
4.1.3 Storms Overhead .................... 102
Earth Field Encounter ................. 102
Glamorous Display .................. 103
4.1.4 Agitation in the Fields .................. 106
Storm Fingerprints .................. 106
Storm Explanations .................. 108
Heating ....................... 111
4.1.5 Measures of Activity ................... ] 15
AE Index ...................... 115
Dst Index ...................... 115
Kp Index ...................... 115
Ap Index ...................... 117
4.1.6 Pulsations ........................ 119
Harvesting the Fields 121
5.1 Field Traces .......................... 121
5.1.1 Early Record Keeping ................. . 121
5.1.2 Modern Field Recording ................. 122
5.1.3 Do-It-Yourself Systems .................. 125
Soda-Bottle Magnetometer .............. 125
Earth-Current Pulsation Sensor ............. 127
5.2 Scientists at Work ....................... 128
5.2.1 Dipole Field Patterns ................... 128
5.2.2 Fluid Velocity at Core-Mantle Boundary .......... 128
5.2.3 Magnetotellurics ..................... 128
5.2.4 Polar Sector Currents 9 130
5.2.5 Dst Storm Index ..................... 130
5.2.6 Pulsations ........................ 131
5.3 Track and Field Records .................... 132
5.4 Space Weather Disturbance Scales .............. 134
5.5 Information Kiosk ....................... 134
5.6 Directions for Further Travel ................. 139
Download: Earth Magnetism - A Guided Tour through Magnetic Fields
Introduce
This book is written by a world-renowned scientist. It provides a wealth ofscientific information about a relevant topic, magnetic fields, in a way that is
state-of-the-science, yet fun to read.
Dr. Campbell has authored several well-known books. His recent book,
Introduction to Geomagnetic Fields, is one of the most important references
in our field. He has also authored numerous articles published in scientific
journals in which his peers subject papers to critical review. In addition, na-
tional and international agencies and corporations routinely seek his advice.
Thus, Dr. Campbell is a respected leader in geophysics and space physics, not
just geomagnetism.
Dr. Campbell carries an unbridled enthusiasm for geomagnetism, which
he is willing and able to share with scientists and nonscientists alike. He
presents the state of the science in a wonderful and meaningful way. The rel-
evant principles and physics of magnetism are discussed in a complete, yet
easy-to-understand way. The Earth's main field and its origin and changes are
simply and clearly presented. Dr. Campbell discusses the effects of particles
and fields of solar, interplanetary, and near-Earth space origin on measure-
ments of the Earth's magnetic field. He presents these external currents as the
result of both normal and unusual solar emissions, including large solar flares
and coronal mass ejections spewing copious fluxes of charged particles with
their associated magnetic and electric fields. These events frequently cause
significant changes in the near-Earth space environment that have been named
magnetic storms and substorms. He presents this information with respect to
its impact on technology in space and on the ground, including telecommu-
nications, satellite operations, satellite drag, and radio propagation, and he
relates these effects to events that occur in our daily lives. He also tackles the
controversial false science as it relates to geomagnetic fields.
Dr. Campbell has accepted the difficult task of talking to all of us about
a complex and difficult-to-understand part of our environment, the magnetic
field of the Earth, and he does so with superb clarity, simplicity, and practi-
cality.
Dr. Herbert W. Kroehl
General Secretary, International Association for
Geomagnetism and Aeronomy
Download: Earth Magnetism - A Guided Tour through Magnetic Fields
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