1. Geospace Variability through the Solar Cycle John Foster MIT Haystack Observatory

2. Introduction – My Geospace Background (Who is the Lecturer? Why will it matter?) Antarctica - Relativistic wave-particle – M/I coupling Canada – International Satellite for Ionospheric Study (ISIS) Utah State Univ. - Alaska incoherent scatter radar studies of auroral disturbances and electrodynamics Yosemite conferences – broad topics in Geospace system science MIT - Radio-physics research investigating M-I-T phenomena from the ground and space Van Allen Probes - Ionospheric effects on magnetospheric processes - -------------------------------------------- I am data/observations oriented. I am NOT a modeler Today we’ll see what the data say about Geospace variability and interconnections

3. 3 Haystack Observatory Millstone Hill Observatory Firepond Optical Facility Millstone Hill Radar MIT Haystack Observatory Complex Westford, Massachusetts Established 1956 Radio Astronomy Atmospheric Science Space Surveillance Radio Science Education and Public Outreach 3

4. Geospace Variability Outline – Lecture #1 What is Geospace? Solar Cycle – Sunspots & EUV Solar Output Cycles in the Ionosphere Seasonal, Local Time and Activity Effects M-I Drivers of the Thermosphere Solar Cycle – Solar Activity Coronal Mass Ejections – Shocks Coronal Holes and High-Speed Stre ams - Solar Rotation – Periodic Disturbances

5. What is Geospace? Geospace is the interconnected environment of our planet. The region of outer space near Earth, including the upper atmosphere, ionosphere and magnetosphere. It includes the Sun’s photosphere, chromosphere and corona, the solar wind, Earth's magnetosheath, magnetosphere, thermosphere, ionosphere and mesosphere. The Geospace system also encompasses the lower atmosphere, oceans, solid earth & Earth’s magnetic field Don’t forget the Biosphere & Man Major defining elements: Earth’s magnetic field, Earth’s atmosphere, and the Sun’s electromagnetic & particle emissions

6. The Coupled Geospace System

11. (top) Solar Minimum (bottom) Solar Maximum NOTE different altitude scales

12. Millstone Hill Incoherent Scatter Radar Mid-Latitude Ionosphere (50-yr database of local observations)

13. Auroral Ionosphere Mid-Latitude Ionosphere Ionospheric Trough

14. Cycles in the Ionosphere Diurnal – Solar production on dayside Latitudinal – Insolation, dipolar magnetic field, M-I coupling Seasonal – Solar inclination and interhemispheric winds, SW – magnetosphere coupling Solar Cycle: Variations in solar output (F10.7 flux) Solar activity effects Statistical empirical models derived from 50 years of incoherent scatter radar observations Millstone Hill – mid/sub-auroral latitude Arecibo – low latitude (near-equatorial processes)

15. Millstone Hill Ap = 15 WinterSummer F10.7 = 70 F10.7 = 150

16. Millstone Hill Ap = 150 WinterSummer F10.7 = 70 F10.7 = 150

17. Arecibo Ap = 15 WinterSummer F10.7 = 70 F10.7 = 150

18. Arecibo Ap=150 WinterSummer F10.7 = 70 F10.7 = 150

19. GPS transmissions sample the ionosphere and plasmasphere to ~20,000 km. Dual-frequency Faraday Rotation Observations give TEC (Total Electron Content) TEC is a measure of integrated density in a 1 m 2 column 1 TEC unit = 10 16 electrons m -2 Hundreds of Ground-Based Receivers ~30 satellites in High Earth Orbit TEC Sampled Continuously along Each Satellite- Receiver Path

20. 20 December 2009 Extended Solar Minimum max log TEC = 1.5

21. 20 December 2013 Solar Maximum max log TEC = 1.8

22. Field-Aligned Currents Link the Magnetosphere and the Ionosphere Joule dissipation of ionospheric currents is a major ionospheric energy source.

23. Joule Heating Rate  P E 2 is determined from individual observations of electric field and Pedersen conductivity over the lifetime of the AE-C satellite. [Foster et al, 1983] The contribution of solar-produced dayside conductivity is important. Joule energy deposition affects the dynamical properties of the thermosphere – winds, temperature, and composition. <PE2><PE2> PP E2E2

24. Seasonal and Activity Variation of Joule Heating - AE-C Data

26. The effects of Solar activity propagate to Earth both promptly (x-ray and radio bursts) and via perturbations in solar wind particle fluxes and magnetic field. Geomagnetic disturbances result from interactions of the solar wind with Earth’s magnetosphere and involve the coupled geospace system.

27. Geomagnetic activity follows the solar cycle. Sunspot number and area indicate the level of magnetic perturbation in the solar photosphere. Associated solar flares and eruptions drive the geospace disturbances. The major contributers to the solar wind disturbances and severe geospace storms exhibit defined solar cycle dependencies. Coronal mass ejections (CMEs) are most numerous during solar maximum, but persist into the early declining phase of the solar sunspot cycle. Coronal holes and resulting solar wind high speed streams are associated with the quieting phase of the solar cycle extending into solar minimum.

28. Coronal Mass Ejection Solar Wind Shock Geomagnetic Storm

29. Solar Wind Shock

31. Propagation of Shock-Induced Pulse through the Inner Magnetosphere [M. K. Hudson et al., JGR, 2015]

32. Energy & L Dependence of Drift Echoes 3.6 MeV 90 keV 350 keV RBSP-B RBSP-A ULF Ringing Universal Time

33. CME occurrence persists into declining phase of solar cycle Coronal mass ejections reach velocities between ~100 to ~ 3,200 km/s with an average speed of~490 km/. These speeds correspond to transit times from the sun out to the mean radius of Earth's orbit of about 15 days to 13 hours and 3.5 days (average). The frequency of CMEs depends on the phase of the solar cycle: from about one every fifth day near the solar minimum to 3.5 per day near the solar maximum. CMEs Sunspots

34. Solar Rotation Coronal Holes High-Speed Streams

35. Solar Rotation Coronal Holes High-Speed Streams Periodic Activity RATE Experiment

36. End of Part I