HANDBOOK OF GEOPHYSICSAND THE

SPACE ENVIRONMENT

SCIENTIFIC EDITOR

Adolph S. Jursa

AIR FORCE GEOPHYSICS LABORATORY

AIR FORCE GEOPHYSICS LABORATORY

AIR FORCE SYSTEMS COMMAND

UNITED STATES AIR FORCE1985

Additional copies of this document can be obtained fromNational Technical Information Service5285 Port Royal RoadSpringfield, VA 22161

Document Accession Number: ADA 167000

ASSISTANT EDITOR

Marylou Tschirch

CONTRIBUTING AUTHORS

Chapter Chapter ChapterAarons, J. 10 Gallery, W.O. 18 Millman, G.H. 10Altrock, R.C. 1 Garrett, H.B. 7 Muench, H.S. 21Anderson, G.P. 21 Glass, M. 16 Murdock, T.L. 25Barnes, A.A. 16 Good, R.E. 18, 21 Neidig, D.F. 1Barron, W.R. 11 Grantham, D.D. 16, 17 Novak, J.M. Capt. USAF 23Basu, S. 10 Gringorten, I.I. 15, 16, 17 O'Neil, R.R. 12Basu, Su 9 Guidice, D.A. 11 Philbrick, C.R. 21Battis, J.C. 23 Hall, L.A. 2 Picard, R.H. 12Bertoni, E.A. 16 Hardy, D.A. 8 Price, S.D. 25Brown, H.A. 16 Hardy, K.R. 16 Radick, R.R. 1Buchau, J. 10 Hecksher, J.L. 10 Rich, F.J. 9, 10Burke, H.K. 20 Heroux, L.J. 2 Rothman, L.S. 18Burke, W.J. 8 Hinteregger, H.E. 2 Rothwell, P.L. 5Cabaniss, G.H. 23 Huffman, R.E. 22 Sagalyn, R.C. 20Champion, K.S.W. 14 Izumi, Y. 15, 16 Sharma, R.D. 13Cipar, J.J. 23 Jekeli, C. 24 Shea, M.A. 6Cliver, E.W. 10, 11 Johnston, J.C. 23 Shearer, J.A. 23Clough, S.A. 18 Kantor, A.J. 14, 15, 16, 17 Shettle, E.P. 18Cohen, I.D. 16 Keil, S.L. Capt. USAF I Simon, G.W. 1Cole, A.E. 14, 15, 17 Klobuchar, J.A. 10 Smart, D.F. 6Cronin, J.P. 11 Knecht, D.J. 4 Spjeldvik, W.N. 5Dandekar, B.S. 10 Kneizys, F.X. 18 Shuman, B.M. 4DeMastus, H.L. 1 Kossey, P.A. 10 Swider, W. 21Dyer, R.M. 16, 19 Kunkel, B.A. 16 Tattelman, P. 15, 16, 17Evans, J.W. 1 Lewis, E.A. 10 Vancour, R.P. 8Falcone, V.J., Jr. 19 Marcos, F.A. 17 Volz, F.E. 18Fenn, R.W. 18 McNamara, L.F. 10 Weber, E.J. 10Feynman, J. 3 Mendillo, M.F. 10 Whalen, J.A. 12Field, E.C. 10 Metcalf, J.I. 16Fitzgerald, D.R. 20 Mill, J.D. Lt. Col. USAF 18

iii

FOREWORD

The space, atmospheric, and terrestrial environments influence the functioning of all Air Force systems. As technologyadvances, the role of the enviroment becomes more important to system performance. In many cases, the environmentdetermines the limit in technical capability. This Handbook reflects the world of geophysics as honed and shaped by thespecial needs of the Air Force.

Today's operational systems were designed with the environmental knowledge made available by the Air Force GeophysicsLaboratory and its predecessor, the Air Force Cambridge Research Laboratories. Tomorrow's Air Force depends on thequality and breadth of today's research as reflected in this Handbook. Although written primarily by Air Force GeophysicsLaboratory scientists, this work reflects the state-of-knowledge of thousands of collaborative investigators, both U.S. andforeign. It is a mixture of basic research and exploratory development, and as such, represents the entire range of ourtechnology based efforts. The very breadth of Air Force operations from space, through the atmosphere, to the earth makesit challenging, exciting, and rewarding to do front line research across this broad spectrum and to present a useable summaryof the results to a wide community via this publication. This Handbook is one of our deliverable end products.

The recognition by the Air Force of the value of geophysics research to its mission is clearly illustrated in this work.The advances made by in-house scientists, the unique world class facilities created to do this work, and the excellent supportof space based experiments, all attest to the long term dedication required to advance our understanding of the environment.Many significant players, military and civilian, have come and gone since the last issue of this Handbook. It is in the contextof pride in these people and pride in our accomplishments for our country that we take great pleasure in dedicating thisbook to the twenty-fifth anniversary of the International Geophysical Year.

J. R. JOHNSON, Colonel, USAF A. T. STAIR, JR.Commander Chief Scientist

V

PREFACE

This fourth edition of the Air Force Handbook of Geophysics and the Space Environment has been completely revised.It was conceived as a commemorative issue in recognition of the twenty-fifth anniversary of the International GeophysicalYear. This was particularly appropriate since the Air Force Geophysics Laboratory-at that time the Air Force CambridgeResearch Center-had been an active participant in the IGY in 1957-58 and the first edition of the Handbook had beenpublished in 1957. The complex task of preparing this edition involved several years of effort during which time the twenty-fifth anniversary of the IGY occurred.

The purpose of the Handbook remains the same, that is, to provide Air Force designers, engineers, and systems operatorswith facts and data about the environment in which the Air Force operates. Extraordinary progress has occurred in thisscientific field since the first edition was published due both to rapid advances in computer capability and the developmentof large rockets and satellites which have made available to experimenters platforms for upper atmosphere and space researchthat did not exist twenty-seven years ago.

The first edition of the Handbook was published the same year the first artificial earth satellite was orbited. At the timeof the third edition, there was considerable activity in space but man had not yet gone to the moon. Since the publicationof the third edition, research in and use of space has grown at an astonishing pace and its importance in man's future is anaccepted fact. The Air Force has been active in space since the development of intercontinental ballistic missiles and earlyreconnaissance satellites, and is preparing for an even more active role as the space shuttle becomes operational.

In keeping with the Air Force interest in space, the format of the Handbook has been arranged to give those chaptersdealing with the space environment increased emphasis. The fourth edition begins with chapters on the sun and its emissions,then treats the earth's magnetic field and the radiation belts, and follows with chapters on the ionosphere and the aurora.The subject of electrical charging of space vehicles has been of special concern to the Air Force and has been included toaid designers interested in that problem. Of no less importance are Air Force operations in the atmosphere and on the earthitself. The next group of chapters deals with properties of the atmosphere, and the Handbook concludes with chapters onthe earth sciences and infrared astronomy.

Readers familiar with earlier editions will note that some chapters of the older versions have been deleted, while newchapters have been added. The choice of subject matter has been determined primarily by changes in today's Air Forcerequirements and operational activities. The contents also are related to the technical programs at the Air Force GeophysicsLaboratory and reflect the expertise of the scientific staff, but should not be considered a technical report on such programs.In fact, the Handbook is only an introduction to several areas of geophysics. Subjects such as galactic x ray astronomy,astrophysics, planetary physics, meteors, some aspects of atmospheric pollution, oceanography, and others not of currentconcern to the Air Force do not appear here. Such subjects are covered very adequately elsewhere.

Numerous references have been included in each chapter so that the reader may pursue a specific subject area to whateverdepth desired. The authors were not constrained by chapter format or length but were allowed to express themselves freely.As a result the chapters range from brief statements on a subject to textbook treatment of others. The Handbook has beenbrought as up to date as possible. Other government organizations such as NASA and NOAA have also published surveysand technical memoranda that deal with aspects of the atmosphere and space environment. Together with this Handbookthey can provide the reader with an up-to-date picture of our understanding of the atmosphere and the near-earth spaceenvironment.

A. S. J.

vii

ACKNOWLEDGMENTS

Many people have contributed to make this edition of the Handbook of Geophysics and Space Environment possible.The decision to proceed with the fourth edition of the Handbook was made by Colonels James Baker and Gerald D'Arcy,Commander and Vice Commander, respectively, of the Air Force Geophysics Laboratory in 1981. We are indebted to theauthors of the twenty-five chapters; without them there would be no Handbook. Recognition is due three co-editors whoundertook the necessary preliminary planning steps to organize the Handbook before I assumed responsibility as scientificeditor. They are Dr. John N. Howard, Dr. Morton Barad, and Dr. Jules Aarons, who also contributed as co-author andscientific editor of Chapter 10. I would like especially to acknowledge the very important contribution of my assistant editor,Marylou Tschirch, who has been primarily responsible for the detailed editing, coordination, and final preparation of themanuscript for publication. Her tireless effort has been a major factor in the success of the Handbook. Mr. John Dempseyassisted with the editing of several chapters as well as contributing his expertise to discussions of format, typesetting, andprinting.

Thanks are due to many secretaries in the Laboratory who typed the draft manuscripts of the chapters for the authorsand, in particular, to Mrs. Ann Turner for her competent and extensive typing, copying, and accomplishment of many otheradministrative tasks that were necessary in the preparation of this Handbook.

A.S.J.

ix

TABLE OF CONTENTS

CHAPTER 1. THE SUN

1.1 THE SUN'S "STEADY-STATE" BEHAVIOR (THE QUIET SUN) ........................ 1-1

1.1.1 Basic Characteristics ........................................................ 1-11.1.2 Solar Rotation ............................................................. 1-51.1.3 The Solar Atmosphere ...................................................... 1-5

1.1.3.1 The Photosphere ........................................ ........... 1-51.1.3.2 The Chromosphere ................................................. 1-91.1.3.3 The Transition Region .............................................. 1-91.1.3.4 The Corona ....................................................... 1-9

1.2 THE ACTIVE SUN ........................................ . 1-13

1.2.1 The Sunspot Cycle ........................................ ................. 1-141.2.2 The Solar Dipole Magnetic Field .............................................. 1-141.2.3 The Emergence and Organization of Magnetic Flux ............................... 1-16

1.2.3.1 Active Regions .................................................... 1-161.2.3.2 Ephemeral Regions ................................................. 1-17

1.2.4 Prominences ............................................................... 1-171.2.5 Coronal Magnetic Fields ........................................ ............. 1-181.2.6 Flares ........................................ ............................ 1-181.2.7 Coronal Activity .................... ....................................... 1-20

1.2.7.1 Coronal Holes and Solar Wind ....................................... 1-201.2.7.2 Streamers ......................................................... 1-211.2.7.3 The Solar Current Sheet ............................................. 1-211.2.7.4 Transients ........................................................ 1-221.2.7.5 Coronal Induced Disturbances ........................................ 1-22

1.2.8 Solar Variability and Climate ................................................. 1-221.2.9 Predictions of Geophysical Disturbances ........................................ 1-23

1.2.9.1 Flare Prediction .................... ...... ..... .............. 1-231.2.9.2 Coronal Disturbance Prediction ....................................... 1-24

CHAPTER 2. SOLAR ULTRAVIOLETIRRADIANCE

2.1 SOLAR UV IRRADIANCE IN THE STRATOSPHERE .................................. 2-1

2.1.1 Solar Spectrum Between 2000 and 3000 A. ............................. 2-1

2.2 SOLAR CONSTANT AND SPECTRAL IRRADIANCE .................................. 2-1

2.2.1 Solar Constant ..................................................... 2-12.2.2 Solar Irradiance Between 1 and 3000 A For Solar Minimum ............... 2-52.2.3 Solar Irradiance Below 1200 A ....................................... 2-14

2.3 ABSORPTION OF SOLAR UV ........................................ .............. 2-16

2.3.1 Absorption Below 3200 A ..... ...................................... 2-162.3.2 UV Atmospheric/Ionospheric Processes ................................. 2-16

2.4 SOLAR UV IRRADIANCE VARIABILITY ........................................... 2-16

2.4.1 Sunspot Number and 10.7 cm Solar Radio Flux .......................... 2-162.4.2 Solar Cycle and UV Variability Below 2000 A ........................... 2-18

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CHAPTER 3. SOLAR WIND

3.1 BASIC THEORY .................................................................. 3-13.1.1 Simple Spherically Symmetric Treatment ....................................... 3-13.1.2 Further Considerations ....................................................... 3-3

3.2 PARTICLE AND FIELD OBSERVATIONS ........................................... 3-4

3.2.1 Coordinates ........................................ 3-43.2.2 Magnetic Fields ........................................ 3-43.2.3 Protons and Electrons ........................................ 3-73.2.4 Other ons ........................................ 3-113.2.5 Waves and Turbulence ...................................................... 3-12

3.3 LARGE SCALE STRUCTURES AND DISCONTINUITIES .............................. 3-153.3.1 Discontinuities ........................................ 3-153.3.2 Solar Wind Streams ........................................ 3-173.3.3 Solar Flare Disturbances ........................................ 3-22

3.4 LONG TERM VARIATIONS ................................................. 3-223.4.1 Solar Cycle ........................ ........................ 3-223.4.2 Secular Variations ........................................ 3-24

3.5 THE CLOSE NEIGHBORHOOD OF THE EARTH ..................................... 3-243.5.1 Magnetosheath ........................................ 3-243.5.2 BowShock ........................................ 3-293.5.3 Upstream Waves and Particles ........................................ 3-31

CHAPTER 4. THE GEOMAGNETIC FIELD

4.1 BASIC CONCEPTS ................................................................ 4-1

4.1.1 Units, Terminology, and Conventions ........................................ 4-14.1.2 Coordinate Systems ......................................................... 4-24.1.3 Sources of the Geomagnetic Field ........................................ 4-54.1.4 The Steady Interior Field ........................................ 4-54.1.5 Quiet Variation External Fields ........................................ 4-74.1.6 Disturbance External Fields ........................................ 4-7

4.2 MEASUREMENTS OF THE GEOMAGNETIC FIELD .......................... 4-8

4.2.1 Instrumentation ........................................ 4-84.2.2 Ground Measurements ................................................ 4-124.2.3 Satellite and Rocket Measurements ........................................ 4-12

4.3 THE MAIN FIELD ........................................... .. 4-13

4.3.1 Basic Description ......... ......... ........................................ 4-134.3.2 The Secular Variation ......................................... 4-164.3.3 Paeleomagnetism ........................................... .4-17

4.4 QUIET VARIATION FIELDS .......................... ............................. 4-19

4.4.1 The Solar Quiet Daily Variation ...... . ....................................... 4-194.4.2 The Lunar Daily Variation ......................................... 4-204.4.3 Magnetospheric Daily Variation ............................................... 4-21

4.5 DISTURBANCE FIELDS ........................................................... 4-21

4.5.1 Geomagnetic Storms and Substorms ........................................ 4-214.5.2 Geomagnetic Pulsations ...................................................... 4-23

4.6 QUANTITATIVE MAGNETIC-FIELD MODELS ....................................... 4-25

4.6.1 The Internal Field .......................... ................................ 4-254.6.2 The External Field .......................................................... 4-27

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4.7 GEOMAGNETIC ACTIVITY INDICES ............................................... 4-27

4.7.1 General-Activity Indices K, Ks, Kp, and Km .................................... 4-274.7.2 Related Indices ap, Ap, ak, Ak, am, and aa ..................................... 4-294.7.3 Character Indices Cp, Ci, and C9 ............................................. 4-314.7.4 Auroral-Electrojet Indices AE, AU,, AL, and Ao ................................ 4-314.7.5 Ring-Current Index Dst ........................................ .............. 4-314.7.6 Other Indices .............................................................. 4-31

4.8 SOURCES OF GEOMAGNETIC DATA ........................................ 4-32

4.8.1 Data Centers ............................................................... 4-324.8.2 International Organizations ................................................... 4-334.8.3 Magnetic Stations ........................................................... 4-334.8.4 Magnetic Field Models ........................................ .............. 4-334.8.5 Activity Indices and Charts .................................................. 4-33

CHAPTER 5. THE RADIATION BELTS

5.1 THEORETICAL PRELIMINARIES .................................................. 5-3

5.1.1 Single Particle Motion ........................................ .............. 5-35.1.2 Adiabatic Invariants ............................... .. ....................... 5-3

5.1.2.1 First Adiabatic Invariant ............................................. 5-45.1.2.2 Second Adiabatic Invariant .......................................... 5-45.1.2.3 Third Adiabatic Invariant ............................................ 5-5

5.1.3 Particle Drift M otion ................................... ............... 5-5

5.2 TRAPPED RADIATION SOURCES .................................... .............. 5-8

5.2.1 Qualitative Description ...................... ................................ 5-85.2.2 Simplifying Assumptions ..................... ................................ 5-9

5.3 TRANSPORT PROCESSES IN THE RADIATION BELTS .................. ... .......... 5-10

5.3.1 Convection ................................................................ 5-105.3.2 Stochastic Processes: Phenomenology .......................................... 5-105.3.3 Effects of Field Fluctuations .................................................. 5-115.3.4 Radial Diffusion ........................................................... . 5-125.3.5 Pitch Angle Diffusion ................ . ...................................... 5-135.3.6 Energy Diffusion ........................................................... . 5-13

5.4 LOSS MECHANISMS ..................................................... ......... 5-13

5.4.1 Exosphere ................................................................ 5-145.4.2 Coulomb Collisions ...................................................... ... 5-145.4.3 Charge Exchange ............................................................ 5-155.4.4 Wave-Particle Interactions .................. ................................. 5-18

5.4.4.1 Pitch Angle Scattering Into the Loss Cone .............................. 5-185.4.4.2 Scattering of Energetic Electrons ......................... .............. 5-19

5.4.4.3 Limit On Radiation Belt Particle Fluxes ................................ 5-205.4.4.4 Strong Diffusion Limit ....................... ....................... 5-21

5.5 THEORETICAL RADIATION BELT MODELS ........................................ 5-21

5.5.1 Quiet Time, Steady State Models ........................... .................. 5-225.5.1.1 Formulation of Boundary Conditions .................................. 5-225.5.1.2 Electron Model .......................... .......................... 5-225.5.1.3 Proton Model ............................................... ....... 5-235.5.1.4 Heavy Ion Models ........................ ......................... 5-245.5.1.5 Theoretical Radiation Belt Ionic Composition ............... ............ 5-26

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5.5.2 Geomagnetic Storms ........................................ ................ 5-265.5.2.1 The Variability of the Parameters ..................................... 5-265.5.2.2 Magnetic Topology Variations ........................................ 5-26

5.6 EMPIRICAL RADIATION MODELS ................................................. 5-27

5.6.1 Data Acquisition and Processing ........................................ 5-275.6.1.1 Protons (Ions) ........................................ 5-275.6.1.2 Heavy Ions ........................................................ 5-305.6.1.3 Trapped Electrons .................................................. 5-315.6.1.4 Shell Splitting Effects ............................................... 5-36

5.6.2 Geosynchronous Altitude Region ........................................ 5-38

5.7 THE RING CURRENT ........................................ 5-42

5.7.1 Electrical Current Relations ........................................ 5-425.7.2 Composition and Sources ........................................ 5-445.7.3 Adiabatic Effects Produced by the Ring Current ................................. 5-45

5.8 RADIATION EFFECTS ON SPACE SYTEMS ....................................... 5-46

5.8.1 Detector Malfunctions ....................................................... 5-475.8.2 Memory Alteration .......................................................... 5-495.8.3 Control System Failure ........................................ 5-495.8.4 Biological Effects ........................................................... 5-50

5.9 MAN'S IMPACT ON THE RADIATION BELTS ....................................... 5-50

5.9.1 Nuclear Detonations ......................................................... 5-505.9.2 Release of Chemicals ........................................ ............... 5-515.9.3 Transmission of Radio Waves ........................................ ........ 5-515.9.4 Effects of Space Structures ........................................ ........... 5-51

CHAPTER 6. GALACTIC COSMIC RADIATIONAND SOLAR ENERGETIC PARTICLES

6.1 NOMENCLATURE AND DEFINITIONS ........................................ 6-1

6.2 GALACTIC COSMIC RADIATION .................................................. 6-3

6.2.1 Primary Cosmic Radiation ........................................ 6-36.2.1.1 Elemental Composition of Primary Cosmic Radiation ..................... 6-36.2.1.2 The Anomalous Cosmic Ray Component ............................... 6-46.2.1.3 Cosmic Ray Electrons ........................................ 6-6

6.2.2 Cosmic Ray Flux Modulations ........................................ 6-66.2.2.1 Solar Cycle Modulations ........................................ 6-66.2.2.2 Short Term Modulations ........................................ 6-8

6.2.3 Geomagnetic Effects ........................................ 6-96.2.3.1 Cosmic Ray Cutoff Rigidities ........................................ 6-9

6.2.4 Charged-Particle Flux Within the Atmosphere ................................... 6-126.2.4.1 The Secondary Cosmic Ray Ionizing Component ........................ 6-136.2.4.2 The Secondary Cosmic Ray Neutron Component ........................ 6-14

6.2.5 Cosmic Ray Albedo ........................................ 6-15

6.3 ENERGETIC SOLAR PARTICLES (SOLAR COSMIC RAYS) ............................ 6-16

6.3.1 The Solar Particle Source ........................................ 6-166.3.2 The Size and Frequency of Solar Particle Events at the Earth ....................... 6-17

6.3.2.1 Solar Proton Events ........................................ 6-196.3.2.2 Solar Electron Events ........................................ 6-22

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6.3.3 Elemental Composition of Solar Particle Events .................................. 6-236.3.3.1 Charged States of Solar Particles ...................................... 6-246.3.3.2 Corotating Energetic Particle Streams .................................. 6-24

6.3.4 Prediction of Solar Proton Events ............................................. 6-246.3.4.1 Propagation of Solar Particles ........................................ 6-246.3.4.2 Particle Increase Onset Time ......................................... 6-266.3.4.3 Time of Maximum Particle Intensity .................................. . 6-266.3.4.4 Magnitude of Maximum Intensity ..................................... 6-276.3.4.5 Proton Event Decay ................................................ 6-276.3.4.6 Differential Energy Spectra .......................................... 6-276.3.4.7 Prediction of Polar Cap Absorption .................................... 6-27

CHAPTER 7. THE CHARGING OF SPACECRAFT SURFACES

7.1 SPACECRAFT CHARGING-HISTORICAL PERSPECTIVE ............................. 7-i

7.2 SPACECRAFT CHARGING OBSERVATIONS ........................................ 7-2

7.2.1 Rocket Measurements ........................................ ............... 7-27.2.2 Satellite Measurements ........................................ .............. 7-37.2.3 The Effects of Spacecraft Charging ............................................ 7-6

7.3 CURRENT MECHANISMS ........................................ ................. 7-10

7.3.1 Time Scales ........................................................... ... 7-117.3.2 Incident Particle Fluxes ....................................... ............. 7-117.3.3 Photoelectron Currents .............................................. . ....... 7-127.3.4 Backscattered and Secondary Electrons ......................................... 7-137.3.5 Magnetic Field-Induced Current Distortions .................................... 7-147.3.6 Motion-Induced Effects ................. ..................................... 7-157.3.7 Charge Deposition by Energetic Particles ....................................... 7-157.3.8 Artificial Charging Mechanisms ............................................... 7-16

7.4 SPACECRAFT CHARGING THEORY ............................ ............ 7-16

7.4.1 Analytic Probe Theory-General Considerations ................................. 7-167.4.2 Analytic Probe Theory-Thick Sheath Models ................................... 7-187.4.3 Analytic Probe Theory-Thin Sheath and Related Models ......................... 7-207.4.4 General Probe Theory ........................................ ............... 7-227.4.5 Numerical Simulation Techniques ........................................ .... 7-257.4.6 NASCAP ........................................ ......................... 7-26

7.5 PREVENTION OF SPACECRAFT CHARGING ........................................ 7-28

7.6 CONCLUSIONS ........................................ 7-29

CHAPTER 8. MAGNETOSPHERIC AND HIGH LATITUDEIONOSPHERIC ELECTRODYNAMICS

8.1 MAGNETOSPHERIC BOUNDARY INTERACTIONS ................................... 8-2

8.1.1 The Magnetopause .......................................................... 8-28.1.2 Convection ........................................ ........................ 8-38.1.3 Boundary Layers ........................................ ................... 8-5

8.2 THE PLASMA SHEET ........................................ 8-6

8.2.1 Adiabatic Motion in the Plasma Sheet ................................ 8-78.2.2 Pitch Angle Diffusion of Plasma Sheet Particles ................................. 8-10

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8.3 ELECTRICAL COUPLING OF THE MAGNETOSPHERE AND IONOSPHERE ............. 8-11

8.4 HIGH LATITUDE ELECTRIC FIELDS ............................................... 8-12

8.5 POLAR CAP ELECTRODYNAMICS ................................................. 8-13

8.5.1 Large Scale Electric Fields Patterns ............................................ 8-138.5.2 Polar Cap Precipitation ...................................................... 8-168.5.3 Polar Cap Arcs ............................................................ 8-17

8.6 AURORAL OVAL ELECTRODYNAMICS ............................................ 8-19

8.6.1 Global Field Aligned Currents ...................................... .. 8-198.6.2 Equatorward Boundary of the Oval ............................................ 8-208.6.3 Inverted-V Phenomenology ................................................... 8-238.6.4 Substorms ................................................................ 8-25

8.7 CONCLUSIONS ........................................ .......................... 8-25

CHAPTER 9. IONOSPHERIC PHYSICS

9.1 STRUCTURE OF THE IONOSPHERE ........... ................................ 9-1

9.1.1 Ionospheric Layers .......................................................... 9-1 9-19.1.2 Chapman Theory for Ionospheric Layers ........................................ 9-29.1.3 Ionization Production, Loss, and Vertical Transport .............................. 9-29.1.4 Neutral Winds and Horizontal Transport ........................................ 9-4

9.2 HIGH LATITUDE PHENOMENA ......... ........................................ 9-4

9.2.1 Total Ionization Trough and Light Ion Trough ................................... 9-49.2.2 The Ionosphere in the Auroral Oval ................................ ........... 9-49.2.3 Substorm Effects ........................................................... 9-59.2.4 Polar Cap Structure ......................................................... 9-5

9.3 EQUATORIAL PHENOMENA ...................................................... 9-6

9.3.1 Sq Current System ................................. ....................... 9-69.3.2 Equatorial Electrojet ........................................................ 9-69.3.3 Electrojet Irregularities ........................................ .............. 9-79.3.4 Equatorial Anomaly and Fountain Effect ........................................ 9-89.3.5 Equatorial F Region Irregularities ............................................. 9-9

CHAPTER 10. IONOSPHERIC RADIO WAVE PROPAGATION

10.1 MEASURING TECHNIQUES ........................................ 10-1

10.1.1 Ionosonde ................... .............................................. 10-110. 1.1.1 Ionogram ......................................................... 10-110.1.1.2 Principles of Ionospheric Sounding .................................... 10-310.1.1.3 Analog lonosonde ....................................... . 10-410.1.1.4 Analog/Digital Hybrid Ionosonde ..................................... 10-510.1.1.5 Digital Ionosondes .................................................. 10-610.1.1.6 Digital Data Processing ............................................. 10-810.1.1.7 FM/CW or Chirp Sounder ........................................... 10-810.1.1.8 Topside Sounders .................................................. 10-1010.1.1.9 lonogram Interpretation .............................................. 10-1110.1.1.10 Ionosonde Network ..................... ............................ 10-13

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10.1.2 Incoherent Scatter ........................................ .................. 10-1410.1.3 Langmuir Probes ........................................ ................... 10-1710.1.4 Faraday Cups for Rockets and Satellites ........................................ 10-1710.1.5 Optical Measurements ....................................................... 10-18

10.1.5.1 Observing Techniques ............................................... 10-1810.1.5.2 Ionospheric Structure from Optical Measurements ........................ 10-18

10.2 SOME ASPECTS OF LONG WAVE PROPAGATION .................................. 10-20

10.2.1 Groundwave Propagation ..................................................... 10-2210.2.1.1 Idealized Flat-Earth Models .......................................... 10-2210.2.1.2 Idealized Spherical-Earth Models ..................................... 10-2410.2.1.3 Models with Earth-Properties Gently Varying Along the Propagation Path .... 10-25

10.2.2 ELF Propagation ........................................ ................... 10-2510.2.2.1 ELF Field-Strength Calculations ...................................... 10-2610.2.2.2 Theoretical and Measured ELF Propagation Constants .................... 10-2610.2.2.3 Anomalous ELF Propagation ......................................... 10-2810.2.2.4 Analysis of Laterally Non-Uniform Ionospheric Disturbances .............. 10-28

10.2.3 Long Range VLF/LF Propagation ............................................. 10-2810.2.3.1 Waveguide Modes .................................................. 10-2910.2.3.2 Waveguide Propagation Equations .................................... 10-2910.2.3.3 TE/TM Mode Structure ............................................. 10-3010.2.3.4 Numerical Modeling of VLF/LF Waveguide Propagation .................. 10-3310.2.3.5 Other VLF/LF Propagation Prediction Techniques ........................ 10-3410.2.3.6 VLF/LF Probing of the Ionosphere .................................... 10-34

10.2.4 MF Propagation ................... ......................................... 10-3610.2.4.1 MF Groundwave Propagation ........................................ 10-3610.2.4.2 MF Skywave Propagation ........................................... 10-3610.4.2.3 Effect of MF Waves on the Ionosphere ................................ 10-36

10.2.5 Long Wave Propagation Through the Ionosphere ................................. 10-37

10.3 IONOSPHERIC MODELING ........................................................ 10-38

10.3.1 The Numerical-Phenomenological Models ...................................... 10-3910.3.1.1 The ITS-78 Model ................................................. 10-3910.3.1.2 The Bent Model ................................................... 10-4010.3.1.3 The Ionospheric Communications Analysis and Prediction Program

(IONCAP) ........................................................ 10-4110.3.1.4 The Bradley Model ................................................. 10-4210.3.1.5 The Air Force Global Weather Central 4-D Model ....................... 10-4310.3.1.6 International Reference Ionosphere-IRI-79 ............................. 10-43

10.3.2 The Theoretical Models ..................................................... 10-4410.3.3 Comparison of the Phenomenological Models, Their Limitations and Ability ......... 10-45

10.4 HIGH FREQUENCY RADIO PROPAGATION ......................................... 10-45

10.4.1 Morphology of the Ionosphere ................... ............................. 10-4710.4.2 Simple Ray Propagation ................... .................................. 10-5110.4.3 Requirements for Successful Communications ................................... 10-5410.4.4 Predictions for HF Communications ........................................... 10-5510.4.5 Problems with HF Communications ............................................ 10-57

10.4.5.1 Multipath Propagation ............................................... 10-5710.4.5.2 SporadicE ........................................................ 10-5710.4.5.3 Problems in High Latitudes .......................................... 10-5710.4.5.4 Problems in Low Latitudes .......................................... 10-5810.4.5.5 Spread F and Irregularities ........................................... 10-58

10.4.6 Disturbances to Normal Communications ....................................... 10-5810.4.7 Unusual Propagation Modes .............................................. .... 10-59

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10.4.8 Short-Term Forecasting of HF Conditions ....................................... 10-6010.4.9 Real Time Channel Evaluation ................................................ 10-6110.4.10 Conclusion ......................................... ....................... 10-62

10.5 IONOSPHERIC DISTURBANCES ........................................ ........... 10-62

10.5.1 Sudden Ionospheric Disturbance (SID) ......................................... 10.6210.5.2 Polar Cap Absorption (PCA) ................................................. 10-63

10.6 HF RADAR IONOSPHERIC CLUTTER ........................................ ...... 10-62

10.6.1 Signal Amplitude ........................................................... 10-6310.6.2 Cross Section .............................................................. 10-6710.6.3 Angular Extent ............................................................. 10-6810.6.4 Doppler Frequency Spectrum ................................................. 10-6910.6.5 Frequency of Occurrence and Correlation with Solar-Geophysical Conditions .......... 10-7010.6.6 Conclusions ........................................ ....................... 10-71

10.7 SCINTILLATION ON TRANS-IONOSPHERIC RADIO SIGNALS . ............... 10-71

10.7.1 GlobalMorphology ........................................ ................. 10-7210.7.2 Scintillation Examples ................... .................................... 10-7210.7.3 Signal Characteristics ................... ..................................... 10-7210.7.4 Frequency Dependency ..................................................... 10-7310.7.5 Fading Spectra .......................................... ................... 10-7310.7.6 Geometrical Considerations ................... ................................ 10-7410.7.7 Spread F and Scintillation .................................................... 10-7510.7.8 Equatorial Scintillations ................... ...... ............................. 10-75

10.7.8.1 Patch Characteristics ................................................ 10-7510.7.8.2 Variation of Scintillation Activity ..................................... 10-7710.7.8.3 In-situ Data ....................... ................................ 10-7710.7.8.4 Sunspot Cycle Dependence ............................ .............. 10-77

10.7.9 Middle Latitude Scintillation ........... .................... .................. 10-7810.7.9. 1 Effect of Magnetic Index on Midlatitude Scintillation ..................... 10-79

10.7.10 The High Latitude Region ............................ .......... ......... 10-7910.7. 10.1 The Plasmapause and the Trough ..................................... 10-7910.7.10.2 Auroral Scintillations .......... ................ .................. 10-8010.7.10.3 Polar Scintillations ........................ .................. 10-81

10.7.11 Empirical Model of Global Scintillation Behavior ................................ 10-8210.7.11.1 WBMOD ......................................................... 10-8210.7.11.2 Formulas in Atlantic Sector ............................. ............. 10-83

10.8 IONOSPHERIC TIME DELAY EFFECTS ON EARTH-SPACE PROPAGATION ........ 10-84

10.8.1 Group Path Delay .......... ............. ................................... 10-8410.8.1.1 Two-Frequency Ionospheric Time Delay Corrections ..................... 10-8410.8.1.2 An Example of a Two-Frequency Ionospheric Time Delay System .......... 10-85

10.8.2 RF Carrier Phase Advance ................... ....... ......................... 10-8510.8.2.1 Differential Carrier Phase ............................................ 10-8510.8.2.2 Second Difference of Carrier Phase ............................ ....... 10-86

10.8.3 Doppler Shift .............................................................. 10-8610.8.4 Faraday Polarization Rotation ................... .............................. 10-8710.8.5 Angular Refraction ................... ..... .................................. 10-8710.8.6 Distortion of Pulse Waveforms ................... .... ........................ 10-88

10.9 IONOSPHERIC TOTAL ELECTRON CONTENT (TEC) ............................... 10-89

10.9.1 Average TEC Behavior ...................................................... 10-8910.9.2 Temporal Variability of TEC ............................ ..................... 10-91

10.9.2.1 Variability from Monthly Mean TEC Values ............................ 10-9110.9.2.2 Short Term Temporal Variability of TEC ............................... 10-9210.9.2.3 Geographic Variability of TEC ....................................... 10-92

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10.9.3 TEC in the Near-Equatorial Region ............................................ 10-9210.9.4 TEC in the Auroral and Polar Cap Regions ..................................... 10-9410.9.5 Protonospheric Electron Content .............................................. 10-9510.9.6 Short Term Variations in TEC ................................................ 10-9510.9.7 Conclusions ............................................................... 10-96

10.10 ARTIFICIAL MODIFICATION ..................................................... 10-96

10.10.1 Chemical Releases .......................................................... 10-9610. 10.2 High Power HF Transmissions ........................................ 10-98

CHAPTER 11. SOLAR RADIO EMISSION

11.1 BASIC DEFINITIONS ........................................ 11-1

11.2 THE MINIMUM (ZERO-SUNSPOT) COMPONENT .................................... 11-2

11.3 THE SLOWLY VARYING COMPONENT ........................................ 11-2

11.4 THE BURST COMPONENT ........................................ 11-2

11.4.1 Meter-Wave Range (25-580 MHz) ............................................ 11-211.4.2 Decimeter-Wave Range (500-2000 MHz) ....................................... 11-311.4.3 Centimeter-Wave Range (2000-35 000 MHz) ................................... 11-3

11.5 CORRECTIONS TO QUIET SUN AND BURST-FLUX DENSITIES ............... 11-4

11.6 QUIET SUN FLUX-DENSITY MEASUREMENTS ..................................... 11-4

11.7 SOLAR RADIO-BURST CLIMATOLOGY BASED ON 1966-1978 SAGAMORE HILLOBSERVATIONS ........................................ 11-6

CHAPTER 12. THE AURORA

12.1 PHENOMENOLOGY, MORPHOLOGY, AND OCCURRENCE ........................... 12-1

12.1.1 General Characteristics of the Aurora .......................................... 12-112.1.1.1 Particle Energy-Ionization and Excitation Height Relation ................ 12-112.1.1.2 Particle Energy-Magnetospheric Regime Relation ....................... 12-112.1.1.3 Spatial Structure . ....................................... 12-212.1.1.4 Morphology of the E Region ......................................... 12-212.1.1.5 Morphology of the F Region ........................................ 12-312.1.1.6 Morphology of the D Region ................ ......................... 12-312.1.1.7 Composite ........................................ 12-4

12.1.2 Distribution of Auroras in Magnetic Latitude and Local Time . .............. 12-412.1.2.1 Statistical Distributions .............................................. 12-512.1.2.2 Instantaneous Distributions ........................................... 12-10

12.1.3 Empirical and Model Relationships ..................................... ...... 12-1312.1.3.1 Auroral Ionospheric Profiles ........................................ 12-1312.1.3.2 Relations Between Auroral Electron, Optical, and Ionospheric Parameters .... 12-1612.1.3.3 Auroral Activity ................................................... 12-1712.1.3.4 Heights of Discrete Auroras .......................... ................. 12-18

12.2 AURORAL OPTICAL AND INFRARED EMISSIONS .................................. 12-19

12.2.1 Laboratory Studies and Auroral Models ........................................ 12-2112.2.2 Artificial Auroral Experiments ..................... ........................... 12-21

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12.2.3 EmissionRates ........................................ .................... 12-2212.2.4 Auroral Processes ........................................................... 12-2312.2.5 Infrared Auroral Emissions ................................................... 12-2712.2.6 Summary .................................................. .............. 12-37

CHAPTER 13. INFRARED AIRGLOW

13.1 SOURCES OF THE INFRARED AIRGLOW ........................................... 13-1

13.1.1 Resonant Scattering of the Earthshine ........................................ 13-113.1.2 Scattering of Sunshine ........................................ 13-213.1.3 Photodissociation ........................................................... 13-213.1.4 Chemical Reactions ......................................................... 13-213.1.5 Atomic and Molecular Collisions .............................................. 13-3

13.2 NON-LOCAL THERMODYNAMIC EQUILIBRIUM (NLTE) ............................. 13-3

13.3 METHODS OF MEASUREMENT ........................................ ........... 13-4

13.4 RESULTS AND DISCUSSION ........................................ 13-6

13.4.1 Thermosphere (above 100 km) ................................................ 13-613.4.2 Lower Thermosphere (between 100 km and 85 km) .............................. 13-713.4.3 Upper Mesosphere (between 85 km and 70 km) .................................. 13-813.4.4 Lower Mesosphere (between 70 km and 40 km) ................................. 13-913.4.5 Infrared Radiators ........................................ 13-10

13.4.5.1 CO2 ........................................ 13-1013.4.5.2 H2O ........................................ 13-1213.4.5.3 NO ........................................ 13-1213.4.5.4 03 ........................................ 13-1213.4.5.5 O2 (Ag) .......................................................... 13-1313.4.5.6 OH ........................................ 13-13

CHAPTER 14. STANDARD AND REFERENCE ATMOSPHERES

14.1 STANDARD ATMOSPHERE ........................................................ 14-1

14.1.1 U.S Standard Atmosphere, 1976 ................... ........................... 14-114.1.1.1 Equilibrium Assumptions ............................................ 14-214.1.1.2 Atmospheric Properties .............................................. 14-214.1.1.3 Atmospheric Structure ............................................... 14-6

14.2 REFERENCE ATMOSPHERES ...................................................... 14-7

14.2.1 Air Force Reference Atmospheres for Altitudes Below 90 Km ...................... 14-714.2.1.1 Basic Assumptions and Formulas ..................................... 14-714.2.1.2 Data ........................................ 14-814.2.1.3 Seasonal and Latitudinal Models ...................................... 14-814.2.1.4 Longitudinal Variations .............................................. 14-2114.2.1.5 Cold and Warm Winter Stratosphere/Mesosphere ........................ 14-23

14.2.2 High Altitude Reference Atmospheres .......................................... 14-2614.2.2.1 Development of Reference Atmospheres ............................... 14-2614.2.2.2 Mean CIRA Reference Atmosphere ................................... 14-2814.2.2.3 Reference Atmospheres 90-120 km ................................... 14-3214.2.2.4 Reference Atmospheres above 120 km ................................. 14-36

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CHAPTER 15. ATMOSPHERIC TEMPERATURES, DENSITY AND PRESSURE

15.1 THERMAL PROPERTIES, SURFACE TO 90 KM ............................. 15-1

15.1.1 Energy Supply and Transformation ............................................ 15-115.1.2 Surface Temperature ........................................ ................ 15-2

15.1.2.1 Official Station Temperature ......................................... 15-215.1.2.2 Daily Temperature .................................................. 15-315.1.2.3 Horizontal Extent of Surface Temperature .............................. 15-515.1.2.4 Runway Temperatures ............................................... 15-715.1.2.5 Temperature Extremes .............................................. 15-715.1.2.6 The Gumbel Model ................................................ 15-1015.1.2.7 Temperature Cycles and Durations .................................... 15-11

15.1.3 Upper Air Temperature ........................................ .............. 15-1415.1.3.1 Seasonal and Latitudinal Variations ................................... 15-1515.1.3.2 Distribution Around Monthly Means and Medians ....................... 15-1615.1.3.3 Distributions at Pressure Levels ....................................... 15-1815.1.3.4 Interlevel Correlation of Temperature .................................. 15-18

15.1.4 Speed of Sound vs Temperature ............................................... 15-1915.1.5 Earth/Air Interface Temperatures .............................................. 15-1915.1.6 Subsoil Temperatures ................... ..................................... 15-2115.1.7 Degree-Day and Temperature-Wind Combinations ................................ 15-29

15.2 ATMOSPHERIC DENSITY UP TO 90 KM ............................................ 15-31

15.2.1 Seasonal and Latitudinal Variations ............................................ 15-3114.2.2 Day-to-Day Variations ....................................................... 15-3115.2.3 Spatial Variations ........................................................... 15-3315.2.4 Statistical Applications to Reentry Problems ..................................... 15-3615.2.5 Variability with Time ....................................................... 15-38

15.3 ATMOSPHERIC PRESSURE UP TO 90 KM .......................................... 15-39

15.3.1 Sea-Level Pressure .......................................................... 15-4615.3.2 Seasonal and Latitudinal Variations ....................... ............ ........ 15-4715.3.3 Day-to-Day Variations ................... .................................... 15-5015.3.4 Diurnal and Semidiurnal Variations ........................................... . 15-51

CHAPTER 16. WATER VAPOR, PRECIPITATION, CLOUDS,AND FOG

16.1 ATMOSPHERIC WATER VAPOR ........................................ ....... 16-1

16.1.1 Surface ......................................... 16-316.1.2 Troposphere ........................................ 16-416.1.3 Stratosphere and Mesosphere ................................................. 16-6

16.2 PRECIPITATION ................................................... 16-8

16.2.1 Surface Rates of Rainfall .................................................... 16-816.2.1.1 Clock Hourly Rates ................................................ 16-816.2.1.2 Instantaneous Rates ................................................ 16-916.2.1.3 Extreme Rates ..................................................... 16-1416.2.1.4 Duration of Rainfall Rates ................... ........................ 16-1516.2.1.5 Rainfall Rates Along Lines .......................................... 16-15

16.2.2 Hail ............................................................... ...... 16-1616.2.2.1 Hailstone Characteristics ............................................. 16-1616.2.2.2 Hailstorm Characteristics ............................................ 16-16

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16.2.2.3 Frequency and Duration at the Ground ................................. 16-1716.2.2.4 HailAloft ........................................................ 16-1716.2.2.5 Area and Line Coverage ............................................ 16-1816.2.2.6 Hail in Design and Operation of Equipment ............................. 16-18

16.2.3 Snowfall .................................................................. 16-1916.2.4 Ice Accretion on Surface Structures ............................................ 16-2016.2.5 Distribution of Precipitation Elements .......................................... 16-22

16.2.5.1 Raindrop Size Distributions .......................................... 16-2216.2.5.2 Snowflakes ........................................ 16-2316.2.5.3 Distribution of Precipitation Elements with Height ....................... 16-2416.2.5.4 Extreme Values of Liquid Water Content ............................... 16-24

16.3 CLOUDS ........................................ 16-26

16.3.1 Surface Observations ................... ..................................... 16-2616.3. 1.1 Summaries of Surface Observations ................................... 16-2716.3.1.2 Global Sky Cover ........................................ .......... 16-3016.3.1.3 Modeling of Cloud Distributions ....................................... 16-30

16.3.2 Cloud Cover in Layers Aloft ................................................. 16-3216.3.3 Satellite and Radar Observations ................... ........................... 16-32

16.3.3.1 Satellites ........................................ ................. 16-3216.3.3.2 Radar ........................................ .................... 16-34

16.3.4 Clear and Cloud-Free Lines-of-Sight ........................................... 16-3416.3.4.1 Aircraft Observations ............................................... 16-3416.3.4.2 Surface Observations ................................................ 16-3416.3.4.3 Comparison of Estimates Between Aircraft and the CFLOS Model Based on

Surface Observations ................................................ 16-3716.3.4.4 Cloud-Free Fields-of-View ........................................... 16-3816.3.4.5 Joint Probabilities of CFLOS ......................................... 16-40

16.3.5 Water Content of Clouds ........................................ ............ 16-4016.3.5.1 Liquid Water Content in Clouds ...................................... 16-4116.3.5.2 Measuring Liquid Water Content ..................................... 16-4116.3.5.3 Supercooled Clouds and Aircraft Icing ................................. 16-41

16.3.6 Clouds Above 6 Km ........................................ ................ 16-4316.3.6.1 Observations of Cirrus Clouds ........................................ 16-4316.3.6.2 Subvisible Cirrus ....................................... ............ 16-4516.3.6.3 Clouds Above the Tropopause ........................................ 16-4516.3.6.4 Tropopause Height ........................................ ......... 16-46

16.4 FOG ............................................................................ 16-46

16.4.1 Microphysical Structure ...................................................... 16-4616.4.1.1 Condensation Nuclei ................................................ 16-4616.4.1.2 Drop Size Distributions ............................................. 16-4716.4.1.3 Liquid Water Content ............................................... 16-47

16.4.2 Visibility ................................................................. 16-4816.4.2.1 Definitions ........................................ ................ 16-4816.4.2.2 Variability ........................................ ................ 16-5016.4.2.3 Relationship Between Extinction Coefficient and Liquid Water Content ...... 16-5316.4.2.4 Modeling of Visibility Distributions .................... ................ 16-54

CHAPTER 17. WINDS

17.1 WIND AS A FUNCTION OF HEIGHT ........................................ 17-1

17.1.1 Variation of Wind Speed with Height (Lowest 100 m) ............................ 17-217.1.2 Wind Direction Shifts (Below 3000 m) ......................................... 17-317.2.3 Diurnal Variation and Low Level Jet Streams (Below 2000 m) ..................... 17-4

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17.2 LARGE SCALE WIND STRUCTURE ................................................ 17-6

17.2.1 Seasonal and Day-to-Day Variations ........................................... 17-717.2.2 Time and Space Variations ................................................... 17-8

17.2.2.1 Time Variability up to 30 km ........................................ 17-1117.2.2.2 Spatial Variability up to 30 km ....................................... 17-1317.2.2.3 Time and Space Variations-30 to 60 km .............................. 17-13

17.3 WIND PROFILES ............................................................. 17-14

17.3.1 Wind Shear ................................................................ 17-1417.3.2 Interlevel Correlations ....................................................... 17-15

17.4 DESIGN DATA ON WINDS ........................................................ 17-21

17.4.1 Hourly Surface Wind Speeds ................................................. 17-2117.4.2 Surface Wind Direction .............................................. 17-2217.4.3 Surface Wind Gusts ................................................. 17-2317.4.4 Extreme Surface Wind Speeds ................................................ 17-2517.4.5 Structure of Jet Streams ........................................ 17-27

17.5 THERMOSPHERIC WINDS ......................................................... 17-29

17.5.1 Observational Summary and Limitations ........................................ 17-3017.5.2 Diurnally Averaged Winds ................................................... 17-31

17.5.2.1 Seasonal Variations at Solar Maximum ................................ 17-3117.5.2.2 Solstice Variations at Solar Minimum ................................. 17-34

17.5.3 Local Time Variations ......................................... 17-3417.5.4 Magnetospheric Convection Effects on Neutral Winds ............................. 17-35

CHAPTER 18. OPTICAL AND INFRARED PROPERTIESOF THE ATMOSPHERE

18.1 ATMOSPHERIC GASES ................... ........................................ 18-1

18.1.1 Atmospheric Molecules, Models of the Atmospheric Composition ................... 18-118.1.2 Molecular Absorption and Spectroscopic Parameters .............................. 18-4

18.1.2.1 The Role of Molecular Absorption .................................... 18-418.1.2.2 The Atmospheric Absorption Line Parameter Compilation ................. 18-5

18.1.3 Index of Refraction .................................. ....................... 18-718.1.4 Molecular Rayleigh Scattering ................................................ 18-7

18.2 AEROSOLS, CLOUD, AND PRECIPITATION PARTICLES ............................. 18-9

18.2.1 Aerosols, Geographic, and Temporal Variations ................................. 18-918.2.1.1 Composition, Sources and Sinks, Refractive Index, Particle Shapes ......... 18-918.2.1.2 Size Distributions .................................................. 18-1018.2.1.3 Vertical Profiles .................................................... 18-1018.2.1.4 Models of Aerosol Properties ........................................ 18-1018.2.1.5 Aerosol Extinction, Scattering, Polarization ............................. 18-15

18.2.2 Cloud, Fog, and Precipitation Particles ......................................... 18-2518.2.2.1 Particle Types, Water-Ice Refractive Index, Particle Shapes ................ 18-2518.2.2.2 Size Distributions ........................... ....................... 18-2818.2.2.3 Cloud-Precipitation Models .......................................... 18-2918.2.2.4 Extinction, Scattering, Polarization ................................ .... 18-30

18.3 SURFACE REFLECTANCE AND ALBEDO ......................................... 18-35

18.4 ATMOSPHERIC TRANSMITTANCE AND RADIANCE ................................ 18-37

18.4.1 Monochromatic Radiation ....................................... ... 18-3718.4.1.1 Line-by-Line Computations (FASCODE) ............................... 18-37

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TABLE OF CONTENTS18.4.1.2 Continuum Absorption .............................................. 18-3918.4.1.3 Radiance and Transmittance for Atmospheric Paths ...................... 18-42

18.4.2 Broad-Band Radiation ..................................... .................. 18-4418.4.2.1 Broad-Band Transmission (LOWTRAN) ............................... 18-4418.4.2.2 Assumptions of the LOWTRAN Model ................................ 18-4618.4.2.3 LOWTRAN Atmospheric Transmittance ............................... 18-4618.4.2.4 LOWTRAN Atmospheric Radiance ................................... 18-4718.4.2.5 Examples of Transmittance and Radiance Spectra ........................ 18-4818.4.2.6 Comparisons of LOWTRAN With Measurements ........................ 18-4818.4.2.7 Limitations of LOWTRAN .......................................... 18-51

18.5 RADIATION TRANSFER BY ATMOSPHERIC SCATTERING ........................... 18-53

18.5.1 Multiple Scattering .................... ............ 18-5318.5.1.1 Formal Solution to the Multiple Scattering Problem ...................... 18-5418.5.1.2 Method of Successive Orders of Scattering ............................. 18-5418.5.1.3 Gauss-Seidel Iterative Method .................... ........ 18-5418.5.1.4 The Matrix Operator or Layer Adding Methods .......................... 18-5518.5.1.5 Monte Carlo Technique .................. ........................... 18-5518.5.1.6 Discrete Ordinates ............................. 18-5518.5.1.7 Dodecaton Approach to Radiative Transfer (DART) ...................... 18-5618.5.1.8 Spherical Harmonic Method ............................ 18-5618.5.1.9 Small-Angle Approximations .................... .............. 18-5718.5.1.10 Approximations of Irradiance ........................... ............ 18-5718.5.1.11 Approximations for the Radiance ..................................... 18-58

18.5.2 Background (Sky) Radiance .................................................. 18-5818.5.3 Illuminance-lrradiance .................. ..................................... 18-6018.5.4 Contrast Transmittance-Visibility .............................................. 18-60

18.6 ATMOSPHERIC REFRACTION ..................................................... 18-65

18.6.1 Refractive Bending ......................................................... 18-6518.6.2 Optical Air Mass ........................................ 18-68

18.7 ATMOSPHERIC OPTICAL TURBULENCE ........................................... 18-69

18.7.1 Amplitude Fluctuations (Scintillation) .......................................... 18-71

CHAPTER 19. ELECTROMAGNETIC WAVE PROPAGATIONIN THE LOWER ATMOSPHERE

19.1 REFRACTION IN THE LOWER TROPOSPHERE ...................................... 19-1

19.1.1 Optical Wavelengths ........................................ 19-119.1.2 Radio Wavelengths ........................................ 19-219.1.3 Standard Profiles of Refractive Modulus ........................................ 19-219.1.4 Variations of Refractive Moduli ............................................... 19-319.1.5 Turbulence ........................................ 19-6

19.2 ATTENUATION AND BACKSCATTERING .......................................... 19-9

19.2.1 Backscattering and Attenuation Cross Sections ................................... 19-1019.2.2 Reflectivity ........................................ 19-1119.2.3 Attenuation by Precipitation .................................................. 19-1319.2.4 Total Attenuation ........................................................... 19-13

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CHAPTER 20. ATMOSPHERIC ELECTRICITY

20.1 FAIR WEATHER ELECTRICITY .................................................... 20-1

20.1.1 Electrical Conductivity ...................................................... 20-120.1.2 Electric Field .............................................................. 20-320.1.3 Currents and Space Charge ................................................... 20-4

20.1.3.1 Air-Earth Conduction Current ........................................ 20-420.1.3.2 Convection Current ................................................. 20-520.1.3.3 Displacement Current ........................................ 20-620.1.3.4 Electrode Effect .................................................... 20-620.1.3.5 Earth Charge and Worldwide Current System ........................... 20-6

20.1.4 Atmospheric Ions .......................................................... 20-620.1.4.1 Definition and Relations ............................................. 20-620.1.4.2 Positive Ion Chemistry and Composition in the Stratosphere

and Troposphere ................................................... 20-820.1.4.3 Negative Ion Chemistry and Composition in the Stratosphere

and Troposphere ................................................... 20-1020.1.5 Electrical Equilibrium and Variations .......................................... 20-11

20.1.5.1 Electrical Equilibrium ............................................... 20-1120.1.5.2 Variations in the Exchange Layer ..................................... 20-1120.1.5.3 Variations in the Free Atmosphere .................................... 20-13

20.1.6 Solar Influence on Earth's Atmospheric Electrical Parameters ............... 20-1520.1.7 Global Model of Atmospheric Electricity ....................................... 20-1720.1.8 Recent Advances in the Middle Atmosphere ..................................... 20-17

20.1.8.1 Middle Atmosphere ................................................. 20-1720.1.8.2 Middle Atmosphere Ion Concentration, Mobility, and Conductivity ......... 20-18

20.2 THUNDERSTORM ACTIVITY ...................................................... 20-20

20.2.1 Thunderstorm Charge Distribution and Electric Field Pattern ............... 20-2020.2.1.1 Surface Electric Field ........................................ 20-2120.2.1.2 Field Patterns Aloft ................................................ 20-22

20.2.2 Lightning Characteristics ..................................................... 20-2620.2.2.1 General Phenomenology of the Discharge .............................. 20-2620.2.2.2 Characteristics of Radio Frequency Signals Due to Lightning .............. 20-27

20.2.3 Precipitation Static Characteristics ............................................. 20-3220.2.4 Distribution and Duration of Thunderstorms ..................................... 20-32

CHAPTER 21. ATMOSPHERIC COMPOSITION

21.1 ATMOSPHERIC OZONE, BELOW 50 KM ............................................ 21-1

21.1.1 Production ........................................ 21-221.1.2 Transport ................................................................. 21-321.1.3 Ozone Measurement ........................................ 21-521.1.4 Total Ozone: Its Global Distribution and Variability .............................. 21-821.1.5 Vertical Profiles ............................................................ 21-921.1.6 Spatial and Temporal Scales of Ozone Variability ................................ 21-1221.1.7 Mathematical Models ........................................................ 21-13

21.2 MINOR CONSTITUENTS IN THE STRATOSPHERE ................................... 21-14

21.2.1 Nitrous Oxide, FC-II, FC-12 and Methyl Chloride (N2O, CCl3F, CCl2F2 and CH3Cl) ..... 21-1621.2.2 Carbon-Containing Species ................................................... 21-16

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21.2.2.1 Carbon Dioxide (CO2) .............................................. 21-1621.2.2.2 Carbon Monoxide (CO) ............................................. 21-16

21.2.3 Hydrogen Containing Species ................................................. 21-2121.2.3.1 Molecular Hydrogen (H2) ........................................... 21-2121.2.3.2 Methane (CH4 ) ......................................... .......... 21-2221.2.3.3 Ethane, Propane, and Acetylene (C2 H6, C3H8, and C2H2) ................. 21-23

21.2.4 Stratospheric Water Vapor (H2O) ................... ........................... 21-2321.2.4.1 Satellite Measurements .............................................. 21-2421.2.4.2 Other Measurements ................................................ 21-24

21.2.5 Odd Oxygen ................... ............................................ 21-2521.2.5.1 Atomic Oxygen (O(3P)) . ....................... ................ 21-26

21.2.6 Odd Nitrogen ................... ........................................... 21-2621.2.6.1 Nitric Oxide (NO) ................................................. 21-2621.2.6.2 Nitrogen Dioxide (NO2) ............................................. 21-3021.2.6.3 Nitric Acid (HNO3) ................................................ 21-3521.2.6.4 Nitrogen Trioxide (NO3) ............................................ 21-3521.2.6.5 Nitrogen Pentoxide (N205) .......................................... 21-3721.2.6.6 Peroxynitric Acid (HO2NO2) ......................................... 21-37

21.2.7 Odd Hydrogen ........................................ ..................... 21-3721.2.7.1 Hydroxyl Radical (HO) ............................................. 21-3721.2.7.2 Hydroperoxyl Radical (HO2) ............................... .......... 21-3821.2.7.3 Atomic Hydrogen (H) .............................................. 21-3821.2.7.4 Hydrogen Peroxide (H20 2) .......................................... 21-38

21.2.8 Odd Chlorine .............................................................. 21-3821.2.8.1 Chlorine Oxide (ClO) ............................................... 21-3821.2.8.2 Hydrogen Chloride (HCl) ............................................ 21-3921.2.8.3 Chlorine Nitrate (ClONO2 ) .......................................... 21-39

21.2.9 Other Halogens .... .............. ...................................... 21-4021.2.9,1 Hydrogen Fluoride (HF) ................... .......................... 21-40

21.3 MESOSPHERE ........................................ ........................... 21-41

21.3.1 The Oxygen Constituents .................................................... 21-4221.3.2 Carbon-Oxygen Constituents .................................................. 21-4421.3.3 Hydrogen-Oxygen Constituents ................................................ 21-4621.3.4 The Nitrogen-Oxygen Constituents ............................................ 21-4621.3 5 Meteoric and Dust Constituents ............................................... 21-4721.3.6 The Inert Gases ............................................................ 21-5021.3.7 Excited Species ............................................................ 21-50

21.4 IONIZED CONSTITUENTS ......................................................... 21-51

21.4.1 Overview ................................................................. 21-5121.4.2 Positive Ion Distributions ................... .............. ............. 21-5321.4.3 Negative Ion Distributions ................... .............. ............. 21-56

CHAPTER 22. ATMOSPHERIC EMISSION AND ABSORPTIONOF ULTRAVIOLET RADIATION

22.1 VUV/UV BACKGROUND ATMOSPHERIC RADIANCE ................................ 22-1

22.2 ABSORPTION AND IONIZATION CROSS-SECTIONS OF MAJOR GASES ............... 22-2

22.3 RATE OF PHOTODISSOCIATION IN THE ATMOSPHERE ............................. 22-4

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CHAPTER 23. GEOKINETICS

23.1 STRUCTURE OF THE EARTH .................................................... 23-1

23.2 PLATE TECTONICS ............................................................... 23-2

23.2.1 Driving Mechanism ......................................................... 23-523.2.2 Plate Motions .............................................................. 23-5

23.3 SHORT PERIOD MOTIONS-SEISMOLOGY ......................................... 23-6

23.3.1 Seismic Waves ............................................................. 23-723.3.2 Earthquakes ........................................ 23-11

23.3.2.1 Spatial Distribution ................................................. 23-1123.3.2.2 Measurement ........................................ 23-1123.3.2.3 Focal Mechanisms and Fault Plane Solutions ............................ 23-1423.3.2.4 Temporal Distribution ............................................... 23-1523.3.2.5 Hazard Evaluation .................................................. 23-1523.3.2.6 Premonitory Phenomena ............................................. 23-18

23.3.3 Other Sources of Seismic Radiation ............................................ 23-1923.3.3.1 Seismic Noise ........................................ 23-1923.3.3.2 Other Sources of Seismic Radiation ................................... 23-20

23.4 LONG PERIOD AND SECULAR EARTH MOTIONS ................................... 23-21

23.4.1 Tectonic Motions ........................................... 23-2123.4.1.1 Horizontal Motions ................................................. 23-2123.4.1.2 Vertical Displacements .............................................. 23-2123.4.1.3 Measurement Techniques ............................................ 23-22

23.4.2 Earth Tides ................................................................ 23-2423.4.2.1 Solid Earth Tides ........................................ 23-2523.4.2.2 Ocean Loading Effects ........................................ 23-2723.4.2.3 Cavity, Topographic and Geological Effects ............................ 23-28

23.4.3 Other Motions ........................................ 23-2923.4.3.1 Motion Background ................................................. 23-2923.4.3.2 Surface Loading ........................................ 23-2923.4.3.3 Thermoelastic Effects ........................................ 23-3023.4.3.4 Soil Moisture and Groundwater ....................................... 23-3123.4.3.5 Conclusions ........................................ 23-34

23.5 ROTATIONAL MOTIONS .......................................................... 23-34

23.5.1 Definition of Azimuth ........................................ 23-3423.5.2 Conventional Azimuth Determination .......................................... 23-3523.5.3 Inertial Azimuth Determination ............................................... 23-37

23.5.3.1 Gyrocompassing ........................................ 23-3723.5.3.2 Wheel Speed Modulation ........................................ 23-3823.5.3.3 Ring Laser Gyroscope ........................................ 23-38

23.5.4 Geophysical and Local Environment Effects on Inertial Instruments ............ 23-3923.5.5 Azimuth Data Base ........................................ 23-4023.5.6 Conclusions ........................................ 23-42

CHAPTER 24. GEODESY AND GRAVITY

24.1 GEOMETRIC GEODESY ... ........................................................ 24-1

24.1.1 Horizontal Control ................... ....................................... 24-224.1.2 Vertical Control ................... ......................................... 24-624.1.3 Inertial Positioning .......................................................... 24-6

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24.2 GRAVIMETRIC GEODESY ......................................................... 24-8

24.2.1 Normal Gravity Field .................................................. ..... 24-824.2.2 Disturbing Gravity Field ......................................... ............ 24-824.2.3 Gravimetry ................................... ............................. 24-1224.2.4 Gradiometry .................................... ........................... 24-12

24.3 SATELLITE GEODESY ......................................................... 24-12

24.3.1 Doppler Positioning ................................. 24-1324.3.2 Satellite Interferometry .............................. ........................ 24-1424.3.3 Laser Ranging ............................................................. 24-1424.3.4 Satellite Altimetry ......................... ................................. 24-14

24.4 GEODETIC ASTRONOMY ..... ........................................ 24-16

24.4.1 Lunar Laser Ranging ........................................ 24-1824.4.2 Very Long Baseline Interferometry ............................................ 24-18

CHAPTER 25. INFRARED ASTRONOMY

25.1 OBSERVATIONAL PARAMETERS ................................................. 25-1

25.1.1 Coordinate Systems ......................................... ................ 25-125.1.2 Time ........................................... ......................... 25-225.1.3 Intensities--Magnitude ........................................ 25-325.1.4 Distance .................................................................. 25-4

25.1.4.1 Parallax .......................................................... 25-425.1.4.2 Standard Candles ................................................... 25-425.1.4.3 Dynamic Distances ............................... .................. 25-525.1.4.4 Extragalactic Distances .............................................. 25-5

25.2 THE SOLAR SYSTEM ............................................................ 25-5

25.2.1 Objects with Negligible Atmospheres ...................................... .... 25-525.2.1.1 Mercury ............................................ .............. 25-725.2.1.2 TheMoon ...................................... .................. 25-725.2.1.3 Asteroids and Planetary Moons ....................................... 25-7

25.2.2 Objects with Optically Thick Atmospheres ...................................... 25-725.2.3 Objects with Semi-Transparent Atmospheres .................................... 25-8

25.2.3.1 Mars ........................................ 25-825.2.3.2 Comets ............................................... 25-8

25.2.4 The Zodiacal Light ........................................ 25-9

25.3 THE GALAXY ....................................................... 25-10

25.3.1 Stars ........................................................... 25-1025.3.1.1 Spectral Classification ........................................ 25-1325.3.1.2 Stellar Luminosities, Colors, and Temperatures .......................... 25-1325.3.1.3 Infrared Stars ..................................................... 25-1325.3.1.4 M Stars ........................................ 25-1325.3.1.5 Carbon Stars ........................................ 25-1525.3.1.6 Planetary Nebulae and Related Objects ................................. 25-1525.3.1.7 Luminous Stars with Infrared Excesses ................................. 25-17

25.3.2 Gas and Dust ........................................ 25-1725.3.2.1 Interstellar Extinction ............................................... 25-1725.3.2.2 HII Regions ....................................................... 25-1825.3.2.3 Molecular Clouds ........................................ 25-18

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25.4 EXTRAGALACTIC OBJECTS ....................................................... 25-18

25.5 THE INFRARED CELESTIAL BACKGROUND ....................................... 25-19

25.5.1 2-8 um ........................... ....................................... 25-1925.5.2 8-30 um ................................................................. 25-21

APPENDIX-UNITS, CONSTANTS, AND CONVERSION FACTORS

INDEX

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