1 / Introduction.- 1.1. Polar Upper Atmosphere and the Outer Magnetosphere.- 1.2. Polar Substorms and Magnetospheric Substorms.- 1.3. Magnetospheric Substorm and Magnetospheric Storm.- 1.4. Auroral Oval as a Natural Coordinate.- 1.5. Four Circumpolar Structures and the Corresponding Magnetospheric Structures.- 1.6. Changing Auroral Oval.- 1.7. Scope of the Monograph.- 2 / Auroral Substorm and Associated Magnetic Disturbances.- 2.1. Introduction: Typical Daily Variation.- A. Auroral Substorm.- B. Polar Magnetic Substorm.- 1. SD Analysis.- 2. Spiral Analysis.- 2.2. Auroral Substorm and Associated Magnetic Disturbances in the Midnight Sector.- 2.3. Auroral Substorm and Associated Magnetic Disturbances in the Evening Sector.- 2.4. Auroral Substorm and Associated Magnetic Disturbances in the Morning Sector.- 2.5. Auroral Substorms in the Geomagnetically Conjugate Areas.- 3 / Polar Magnetic Substorm.- 3.1. Introduction.- 3.2. Polar Magnetic Substorms on December 13, 1957.- 3.3. Polar Magnetic Substorm on December 16, 1964.- 3.4. Three-Dimensional Model Current System.- 3.5. Polar Magnetic Substorms in Geomagnetically Conjugate Areas.- 4 / Ionospheric Substorm.- 4.1. Introduction.- 4.2. Typical Daily Variation of the Cosmic Radio Wave Absorption.- 4.3. Statistical Daily Variation Pattern.- 4.4. N Type Absorption.- 4.5. E Type Absorption.- 4.6. M Type Absorption.- 4.7. Cosmic Radio Noise Absorption at Geomagnetically Conjugate Areas.- 4.8. Development of the Ionospheric Substorm (Absorption).- 4.9. Deformation of the Ionosphere.- 4.10. Radio Auroras.- 4.11. Atmospheric Wave Substorm.- A. Traveling Disturbances.- B. Infrasonic Pressure Waves from Active Auroras.- 4.12. Atmospheric Heating in the Auroral Zone.- 5 / X-Ray Substorm.- 5.1. Introduction.- 5.2. Typical Daily Variation.- 5.3. Statistical Daily Variation Pattern.- 5.4. Midnight Bursts.- 5.5. X-Ray Bursts Associated with Westward Traveling Surges.- 5.6. X-Ray Bursts in the Morning and Midday Hours.- 5.7. Fine Structures of the X-Ray Bursts.- 5.8. X-Ray Bursts at the Geomagnetically Conjugate Areas.- 5.9. Development of the X-Ray Substorm.- 6 / Proton Aurora Substorm.- 6.1. Introduction.- 6.2. Typical Daily Variation.- 6.3. Statistical Daily Variation Pattern.- 6.4. Protons in the Auroral Bulge and Patches.- 6.5. Protons and Westward Traveling Surges.- 6.6. Development of the Proton Aurora Substorm.- 7 / VLF Emission Substorm.- 7.1. Introduction.- 7.2. Typical Daily Variation.- 7.3. Statistical Daily Variation Pattern.- 7.4. N1 Type Event and Westward Traveling Surges.- 7.5. N2 Type Event in the Midnight Sector.- 7.6. N3 and D Type Events.- 7.7. Development of the VLF Emission Substorm.- 8 / Micropulsation Substorm.- 8.1. Introduction.- 8.2. Typical Daily Variations.- 8.3. Statistical Daily Variation Pattern.- A. Pi-2 Pulsations.- B. Pulsations in High Latitudes.- 8.4. Micropulsations in the Auroral Bulge.- 8.5. Micropulsations and Positive Bays.- 8.6. Micropulsations and Pulsating Patches in the Morning Sector.- 8.7. Micropulsations in the Daytime (10-15 LT).- 8.8. Micropulsations in the Afternoon Hours.- 8.9. Pi-2 Pulsations.- 8.10. Development of the Micropulsation Substorm: Figure 125.- 9 / Satellite Observations During Polar Substorms.- 9.1. Introduction.- 9.2. Magnetic Field and Particle Flux Variations at re = 6.6a: Synchronous Satellite (ATS).- A. Magnetic Field.- 1. Midnight Sector.- 2. Evening Sector.- 3. Midmorning Sector.- B. Electrons (50 keV).- C. Electrons (0.4-2 MeV).- 9.3. Magnetic Field and Particle Flux Variations in the Range re = 4a?15a.- A. Magnetic Field.-45 keV).- 3. Energetic Protons (>0.31 MeV).- B. Magnetic Field.- 9.5. Trapping Region of the Magnetosphere (re Stations in the Southern Hemisphere.- List of Geomagnetic Observatories compiled by the World Data Center A.- Time Comparison Table for College, Alaska.- Index of Names.- Index of Subjects.

It has become increasingly clear that the magnetosphere becomes intermittently unstable and explosively releases a large amount of energy into the polar upper atmos­ phere. This particular magnetospheric phenomenon is called the magnetospheric sub­ storm. It is manifested as an activity or disturbance ofvarious polar upper atmospheric phenomena, such as intense auroral displays and X-ray bursts. Highly active conditions in the polar upper atmosphere result from a successive occurrence of such an element­ ary activity, the polar substorm, which lasts typically of order one to three hours. The concept of the magnetospheric substorm and its manifestation in the polar upper atmosphere, the polar substorm, has rapidly crystallized during the last few years. We can find a hint of such a concept in the term 'polar elementary storm' introduced by Kristian Birkeland as early as 1908. However, we are greatly indebted to Sydney Chapman, who established the basic foundation of magnetospheric physics and has led researches in this field during the last half century. Indeed, the terms 'polar magnetic substorm' and 'auroral substorm' were first suggested by Sydney Chapman. The concept of the substorm was then soon extended by Neil M. Brice of Cornell University, and Kinsey A. Anderson and his colleagues at the University ofCaliforrlia, Berkeley, who introduced the term 'magnetospheric substorm'. We owe many of these recent developments in magnetospheric physics to the great international enterprise, the International Geophysical Year (IGY) and subse­ quent international cooperative effort (IGC, IQSY).