1. Space Weather: The Sun, Magnetosphere, Ionosphere

2. Source of Space Weather / Ionospheric Disturbances: The Sun

3. The Sun: The Sun for a a couple months in 2001 Facts (approximate values): 149 million kilometers away Diameter: 1.4 million km Mass: 2.0x10 30 kg 4.5 billion years old 11 Year sunspot cycle Surface temp. 5,900 K. Rotation Period: 27 days at equator

4. Close-up of a Sun Spot

5. Local Internal Dynamics Animation showing our present understanding Coronal “loops” on the Sun

6. Coronal Mass Ejections Super prominence EUV images of Sun with corona as observed from SOHO

7. Coronal Mass Ejection Causing the Aurora

8. Magnetosphere Other effects include satellite damage, power outages, GPS errors, radio interruptions, etc.

9. The Magnetosphere

10. The Aurora As seen from space As seen in Alaska

11. Solar Flares EUV X-RAY “ White Light ” Extreme Ultraviolet (EUV)X-ray Flare

12. Troposphere Stratosphere Mesosphere Thermosphere D-Region E-Region F 1 -Region F 2 -Region Neutral AtmosphereDaytimeNighttime Height 100 km 200 km 300 km    Mt. Everest

13. Formation of the Ionosphere EUV Light Neutral Atoms Positively Charged Ion Free Electrons, these reflect radio waves Photo-ionization SUN   A (Atom)  A + (Ion) + e - (electron) Photo-ionization occurs when Extreme Ultraviolet (EUV) from the Sun strikes neutral atoms to produce positively charged Ions Types of Atoms: primarily Oxygen & Nitrogen Types of Molecules: O 2, N 2, NO

14. Two Types of Recombination: Molecule A 2   Ion X + Charge Exchange X + + A 2  AX + + A AX + A Dissociation Recombination AX + + e -  A + X o Single Atom A Neutral Atom X Radiative Recombination X + + e -  A + Radiated Energy  A Ion X + e-e- Dissociation recombination, 2 steps: Radiative recombination, 1 step: Electron splits AX + apart

15.       When ions are “ let go ” they oscillate in simple harmonic motion at an Angular Frequency   2 = N e 2 /  0 m N = Electron Density e = Charge on electron m = Mass of an electron  0 = Permittivity of free space Angular Plasma Frequency (maximum usable frequency): f N = 2  /  f N = Plasma frequency in Hertz f N 2 = 80.5 NSubstituting Atomic Constants f c  9 x 10 -6 √ N m f c = Critical Frequency, N m = Electron density Reflectivity of the Ionosphere

16. Electron Density vs. Height D - Region 90 Km, Lower following solar flare 1.5x10 4 N e /cm3 (noon) Absent at Night E - Region 110 Km 1.5x10 5 N e /cm3 (noon) 1.0x10 4 N e /cm3 (Night) F1 - Region 200 Km 2.5x10 5 N e /cm3 (noon) Absent at night F2 - Region 300 Km 10 6 N e /cm3 (noon) 10 5 N e /cm3 (Midnight) Source: “ The Ionosphere: Communications, Surveillance, and Direction Finding ” Leo F. McNamara1991 ISBN: 0-89464-040-2

17. Maximum Useable Frequency The Maximum Useable Frequency (MUF) is the largest frequency that can be reflected by the ionosphere at vertical incidence Source: “ The Ionosphere: Communications, Surveillance, and Direction Finding ” Leo F. McNamara1991 ISBN: 0-89464-040-2

18. Variability of the Ionosphere Diurnal (Thru the day) Seasonal (Thru the year) Location (Geographic & Geomagnetic) Solar Activity (Solar Cycles & Disturbances) Height (at different layers) Source: “ The Ionosphere: Communications, Surveillance, and Direction Finding ” Leo F. McNamara1991 ISBN: 0-89464-040-2