Ionospheric Effects of Solar Flares

1 / Introduction.- 2 / Description of SID Techniques and Observations.- 2.1. The Sudden Enhancement of Atmospherics (SEAs).- 2.2. Sudden Enhancement of Signal Strengths (SES), Sudden Field Anomalies (SFA).- 2.3. Sudden Phase Anomalies (SPA).- 2.4. Short Wave Fadeouts (SWF).- 2.5. Sudden Cosmic Noise Absorption (SCNA).- 2.6. Sudden Increase of fmin (SIF).- 2.7. Flare Effects Observed with Pulsed Transmitters.- 2.8. Sudden Frequency Deviations.- 2.9. Wave Interaction Technique.- 2.10. Partial Reflection Observations.- 2.11. Satellite Radio Beacon Experiment — Changes in Total Electron Content (SITEC).- 2.12. Incoherent-Scatter Technique.- 2.13. Rocket Soundings.- 2.14. A Comparative Evaluation of Electron Density Profile Errors.- 3 / Flare Radiations Responsible for Ionospheric Effects.- 3.1. Quiet-Day Solar Flux in the EUV and X-Ray Regions.- 3.2. Flaretime Enhancements in XUV Fluxes.- 3.3. X-Ray Spectral Development.- 3.3.1. The Equivalent Spectrum.- 3.3.2. The Composite Spectrum.- 3.3.3. Spectral Development Based on Free-Free (Bremsstrahlung) and Radiative Recombination Transitions.- 3.4. Photoelectrons During Flares.- 4 / SID Phenomenology.- 4.1. Occurrence of SIDs with X-Ray, EUV Flares and Microwave Bursts.- 4.1.1. D-Region SIDs and X-Ray Fluxes and Microwave Bursts.- 4.1.2. F-Region SIDs and EUV Flux.- 4.2. Threshold X-Ray Flux for the Production of an SID.- 4.3. Level of Solar Radio Flux in the 3000 MHz Region and Its Relation to the Occurrence of Sudden Ionospheric Disturbances.- 4.4. The Size Correlation.- 4.5. Time of Growth and Relaxation Time.- 4.5.1. SEA Types and Cosmic Rays.- 4.6. SDA Characteristics and Implications.- 4.7. Examinations of Complete Time Profiles of X-Ray Flares, Radio Noise Bursts and SID Effects.- 5 / Some Simple Analysis Techniques.- 5.1. Photoionization Rates and Equations of Continuity.- 5.2. Use of Relaxation Time.- 5.3. Decay Curve Analysis.- 5.3.1. Principle of the Decay Curve Analysis.- 5.3.2. Decay Curves Analysis for Absorption Events.- 5.3.3. Decay Curves of SPAs.- 5.3.4. Decay Curves of Magnetic Crochets.- 5.4. Simultaneous Correlation of ?? and ? A.- 5.5. Zenith Angle Dependence of SIDs.- 6 / Some Outstanding Solar Flare Events.- 6.1. Ionospheric Effects of the Flare of July 7, 1966.- 6.2. Ionospheric Effects of the Solar Flares of May, 1967.- 6.3. Ionospheric Effects of the Solar Flare of July 8, 1968.- 6.4. Ionospheric Effects of August 1972 Flare Events.- 7 / Development of Electron Density Profiles From Synoptic SIDs.- 7.1. Profiles from SCNA Measurements.- 7.2. Profile Determination from Simultaneous Use of SCNA and SPA Measurements.- 7.3. Profiles from Phase and Amplitude Measurements at VLF.- 8 / D-Region Ionization Profiles and Loss Rates During Flares.- 8.1. Flare Ionization Profiles.- 8.2. Loss Rate During Flares.- 8.2.1. From Quantitative Relationship of Flare X-Rays to SIDs.- 8.2.2. Average Profiles for Weak, Moderate and Strong Flare Conditions.- 9 / SIDs as a Tool for the Study of Aeronomy and Ion Chemistry.- 9.1. Photoionization Rates During Solar Flares.- 9.2. Minor Neutral Constituents in the Mesosphere.- 9.2.1. Nitric Oxide in Mesosphere.- 9.2.2. Ozone in Mesosphere.- 9.2.3. Water Vapour and Other Hydrogen Compounds.- 9.3. Ion Composition.- 9.3.1. Ion Composition in the D-Region.- 9.3.2. Ion Composition in E- and F-Regions.- 9.3.3. Ion Chemistry.- 9.3.3.1. Important Reaction Rates.- 9.3.3.2. Positive Ion Schemes.- 9.4. Information on Nitric Oxide from Simultaneous Measurements of Electron Density and Solar X-Rays During Flares.- 9.5. Chemistry of D-Region During Flares.- 9.5.1. Chemistry at 80 km.- 9.5.2. Negative Ion Regions (70 km and below).- 9.5.3. Models of Flaretime Ionization Profiles.- 9.6. F-Region During Flares.- 9.6.1. Ionization Changes.- 9.6.2. Effective Loss Rate.- 10 / SIDs as Flare Radiation Monitoring Techniques.- 10.1. Information on the X-Ray Region.- 10.1.1. VLF Observations.- 10.1.2. HF Absorption Phenomena Including SCNA Observations.- 10.2. Information on EUV Flux from F-Region SIDs.- 10.2.1. EUV from Ionograms During Flares.- 10.2.2. SFDs as Ultraviolet Monitor.- 10.2.3. XUV Flux Determinations from Incoherent Scatter Observations.- 10.2.4. Combined EUV Information from F-Region SIDs.- 11 / Polar Cap Absorption Events.- 11.1. Radio Measurement Techniques.- 11.1.1. Use of Riometers.- 11.1.2. Use of Ionosondes.- 11.1.3. Partial Reflections.- 11.1.4. LF and VLF Observation.- 11.1.5. Oblique HF Propagation.- 11.1.6. VHF Forward Scatter.- 11.2. PCA Morphology.- 11.2.1. Classification of PCA Events.- 11.2.2. Microwave-Millimeter Wave Solar Radio Bursts and Proton Flux.- 11.2.3. Twilight Effect.- 11.2.4. Solar Cycle Variations in the PCAs.- 11.3. November 1969 PCA Events.- 11.4. Principal Aeronomic Features of the Lower Ionosphere During a Major PCA.- 11.5. Chemistry of the Lower Ionosphere During PCAs.- References.- Special Data Volumes, Books and Conference Proceedings.- Index of Names.- Index of Subjects.