Physics and Chemistry in Space

1 The Occurrence and Cause of Auroras: a Short Introduction.- 1.1 Local Auroral Forms.- 1.1.1 Geometry.- 1.1.2 Intensity.- 1.1.3 The Local Auroral Display.- 1.2 Auroral Morphology.- 1.2.1 Magnetic Guiding of Auroral Particles; Coordinate Systems.- 1.2.2 Worldwide Auroral Morphology.- 1.2.3 Mid-Latitude Red Arcs.- 1.2.4 Polar Glow and Mantle Auroras.- 1.3 Particle Behaviour: Reflection, Absorption and Scattering.- 1.3.1 Mirror Effects.- 1.3.2 Absorption and Scattering of Particles in the Atmosphere.- References.- 2 The Electron Aurora: Main Characteristics and Luminosity.- 2.1 Introduction.- 2.2 N2+ Emission and Ionization.- 2.3 Theoretical Height Distribution of the First Negative N2+ Bands.- 2.4 Height Distribution of Other Emissions.- 2.5 Electron Energies Inferred from Height Distribution of Auroral Luminosity.- 2.6 Geometry and Motion of the Electron Aurora.- 2.7 Latitude Variations in Auroral Heights.- References.- 3 The Proton Aurora.- 3.1 Introduction.- 3.2 Theory of Hydrogen Line Emission.- 3.2.1 Auroral Protons, the Solar Wind and the Magnetosphere.- 3.2.2 The Proton Beam in the Atmosphere: Charge Exchange.- 3.2.3 The Proton Beam in the Atmosphere Diffusion.- 3.2.4 Excitation of the Hydrogen Lines.- 3.2.5 The Relation Between Hydrogen Lines and the First Negative N2+ Bands.- 3.2.6 The Hydrogen Line Profiles.- 3.2.7 Height Distribution of the Hydrogen Emissions.- 3.3 Observations on Hydrogen Lines.- 3.3.1 Techniques.- 3.3.2 The Intensity Ratio Between the Hydrogen Lines and the First Negative N2+ Bands.- 3.3.3 Absolute Intensities and Balmer Decrement.- 3.3.4 Geometry of Proton Aurora.- 3.3.5 Morphology of Proton Aurora.- 3.3.6 The Doppler Profiles.- References.- 4 The Optical Spectrum of Aurora.- 4.1 Description.- 4.1.1 Introduction.- 4.1.2 The Auroral Spectrum.- 4.1.3 Forbidden Atomic Emissions.- 4.1.4 Permitted Atomic Emissions.- 4.1.5 Molecular Emissions.- 4.1.6 The Intensity Distribution in the Spectrum.- 4.2 Local Variations in the Spectrum.- 4.2.1 Introduction.- 4.2.2 The I(5577)/I(1 neg)Ratio.- 4.2.3 Other Forbidden Emissions.- 4.2.4 Permitted Atomic Lines.- 4.2.5 Permitted Molecular Bands.- 4.3 Latitudinal and Zonal Variations.- References.- 5 Physics of the Optical Emissions.- 5.1 Excitation.- 5.1.1 Fast Particle Impact.- 5.1.2 Thermal Collisions.- 5.1.3 Excitation by Thermal Electrons.- 5.1.4 Discharge Mechanisms and Heating by Electric Fields.- 5.2 Deactivation.- 5.3 Interpretation of the Spectrum.- 5.3.1 Atomic Lines.- 5.3.2 The Intensity Distribution within Molecular Band Systems.- 5.4 The Lifetime of Metastable Oxygen Atoms.- 5.5 Helium Emissions.- 5.6 Sunlit Aurora.- Appendix (References to Data on Cross-Sections).- References.- 6 Temperature Determinations from Auroral Emissions.- 6.1 Introduction.- 6.2 Doppler Temperatures.- 6.3 Rotational Temperatures.- 6.4 Conclusions and Prospects.- References.- 7 Pulsing Aurora.- 7.1 Introduction.- 7.2 Pulsating Aurora.- 7.2.1 Definition.- 7.2.2 Observations.- 7.3 Flaming Aurora.- 7.4 Flickering Aurora.- 7.5 Streaming Aurora and Horizontal Waves.- 7.6 Correlation with Pulsations in the Magnetic Field and Telluric Currents.- 7.7 Correlation with Pulsations in X-Rays.- 7.8 Morphology of Pulsating Aurora.- References.- 8 Optical Aurora and Radio Observations.- 8.1 Introduction.- 8.2 Radio Absorption.- 8.3 E-Layer Ionization.- 8.4 Radio Auroras.- 8.5 VLF Radio Emissions and Radio Noise.- 8.6 Polar Cap Absorption (PCA) Events.- References.- 9 Auroral X-Rays.- 9.1 Production of X-Rays in Aurora.- 9.2 Observations.- References.