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The Effect of Large By on Currents in the Polar Cap

The Effect of Large By on Currents in the Polar Cap. Robert C. Allen, Sophia J. Cockrell, Ramon E. Lopez, Dustin Brewer, Elizabeth J. Mitchell. Department of Physics, University of Texas at Arlington. TSAPS Fall 2009. Importance:. Solar Wind:. Plasma Super-sonic. Courtesy of SWPC.

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The Effect of Large By on Currents in the Polar Cap

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  1. The Effect of Large By on Currents in the Polar Cap Robert C. Allen, Sophia J. Cockrell, Ramon E. Lopez, Dustin Brewer, Elizabeth J. Mitchell Department of Physics, University of Texas at Arlington TSAPS Fall 2009

  2. Importance:

  3. Solar Wind: • Plasma • Super-sonic Courtesy of SWPC

  4. Interplanetary Magnetic Field (IMF) • Since the solar wind is highly conductive it carries the sun’s magnetic field with it creating an interplanetary magnetic field (IMF).

  5. IMF’s Interaction with Earth • When Bz is Northward little interaction occurs • When Bz is Southwards there is reconnection Courtesy of http://www.aldebaran.cz/astrofyzika/plazma/reconnection/reko.gif

  6. Solar Wind Conditions • What do we look at? • Magnetic Field • Flow Speed • Density • Electric Field Y • Mach number Courtesy of CDAWeb

  7. DMSP F13 • Defense Meteorological Satellite Program • 101 minute polar orbit • Roughly Dawn/Dusk orbit Courtesy of UTD Courtesy of UTD

  8. Polar Cap Boundary • “Open” Field lines • Closed Field lines

  9. Polar Cap Boundary • How do we find the Polar Cap Boundary? Courtesy of Auroral Particle and Imaging (AFRL and JHU/APL)

  10. Convection Reversal Boundary • E x B drift Wikimedia Courtesy of OULU

  11. Convection Reversal Boundary • How do we find the Boundary? Courtesy of UTD

  12. Downward Precipitation Courtesy of Auroral Particle and Imaging (AFRL and JHU/APL)

  13. Search Parameters • Solar Wind: • |By| > 6 nT • |By| > 1.5 |Bz| • Alfvén mach number > 6 • Steady Solar Wind parameters for at least 45 minutes before Convection Reversal Boundary • F13: • Reliable data flags • Travel through the 80˚ Magnetic Latitude region • Polar Cap potential > potential offset.

  14. Sorting of cases: • Positive By and Negative Bz • 0 Cases of Precipitation • 12 Cases of No Precipitation • Positive By and Positive Bz (Expect to be in the NH) • 3 Cases of Precipitation (3 NH) • 12 Cases of No Precipitation • 6 Cases of Maybe Precipitation (4 NH, 2 SH) • Negative By and Negative Bz • 0 Cases of Precipitation • 7 Cases of No Precipitation • 2 Cases of Maybe Precipitation (2 SH) • Negative By and Positive Bz (Expect to be in the SH) • 1 Case of Precipitation (1 SH) • 5 Cases of No Precipitation • 4 Cases of Maybe Precipitation (3 NH, 1 SH) • 2 Cases of All Precipitation (2 SH)

  15. Comparing asymmetry of Polar Cap Potential with |By| • Plotting the asymmetry of the Polar Cap Potential with |By| shows logarithmic(?) growth. Positive Bz 3 points removed. All data points

  16. Future work • Look at F12 and F15 DMSP Satellites for more cases • Compare with simulation results • Conduct additional statistical analysis between precipitation and the environment.

  17. Bibliography • OMNI Filtering Service • http://omniweb.gsfc.nasa.gov/ • CDAWeb http://cdaweb.gsfc.nasa.gov/ • UTD DMSP site http://cindispace.utdallas.edu/DMSP/dmsp_data_at_utdallas.html • Auroral Particles and Imagery site http://sd-www.jhuapl.edu/Aurora/spectrogram/index.html

  18. This material is based upon work supported by CISM, which is funded by the STC Program of the National Science Foundation under Agreement Number ATM-0120950

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