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The viscous interaction potential during the Whole Heliosphere Interval – one solar rotation

R. Bruntz 1 , R. E. Lopez 1 , S. K. Bhattarai 1 , K. H. Pham 1 , Y. Deng 1 , Y. Huang 1 , M. Wiltberger 2 , and J. G. Lyon 3 Department of Physics, University of Texas at Arlington National Center for Atmospheric Research, High Altitude Observatory

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The viscous interaction potential during the Whole Heliosphere Interval – one solar rotation

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  1. R. Bruntz1, R. E. Lopez1, S. K. Bhattarai1, K. H. Pham1, Y. Deng1, Y. Huang1, M. Wiltberger2, and J. G. Lyon3 Department of Physics, University of Texas at Arlington National Center for Atmospheric Research, High Altitude Observatory Department of Physics and Astronomy, Dartmouth College Fall 2011 Texas APS/AAPT/SPS Meeting Texas A&M University – Commerce October 6-8, 2011 The viscous interaction potential during the Whole Heliosphere Interval – one solar rotation Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  2. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Outline Introduction Methodology Results Conclusions Acknowledgements References

  3. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 The Sun, the solar wind, and Earth’s magnetosphere

  4. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 The ionospheric “reconnection potential” is produced by reconnection between the interplanetary magnetic field (IMF) and Earth’s magnetic field.

  5. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 The ionospheric “viscous potential” is produced by the viscous interaction with the solar wind.

  6. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 The solar wind during the Whole Heliosphere Interval (WHI)

  7. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Details of the LFM magnetospheric simulation • Lyon-Fedder-Mobarry code is a fully 3-D MHD simulation, which can be run with real solar wind input • The magnetosphere is modeled via ideal MHD equations within 25 to -300 RE (x) and 100 RE (y, z) • Upstream and side boundary conditions (BCs) = solar wind data • Downstream BC = supersonic outflow • Inner BC = 2-D ionospheric simulation

  8. LFM Output • Output of the LFM code, showing cut planes displaying density Close-up of the ionosphere in an LFM simulation. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  9. Fall 2011 Tx. APS/AAPT/SPS Meeting Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Comparison of the full LFM run cross-polar cap potential (CPCP) and the B0 run CPCP.

  10. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 The viscous-only (B0) CPCP can be a significant fraction of the full-run CPCP for southward Bz.

  11. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Comparing the B0 run and the Bruntz et al. [2011a] viscous potential, using γ = 1.542

  12. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Scaling the Weimer [2005] CPCP by gamma and comparing it to the full LFM CPCP

  13. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Conclusions • The viscous potential can be a significant fraction of the CPCP, even during strongly southward Bz. • Bruntz et al. [2011a] VP formula is based on ΣP = 10 mhos; WHI runs used F10.7 = 74 SFU. Scaling the former by γ = 1.542 gives good agreement with the potentials in the B0 run. • Scaling the Weimer [2005] CPCP by γ gives good agreement with the full LFM CPCP, even though γ is not directly based on either. This implies γ is more than a “fudge factor;” ionospheric conductivity is too low in LFM. Looking for a Post-doc? Let’s talk!

  14. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Acknowledgements 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. The National Center for Atmospheric Research is sponsored by the National Science Foundation. Y. Deng’s effort at the University of Texas at Arlington was supported by the Nation Science Foundation under ATM0955629.

  15. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 References Axford, W. I., and C. O. Hines (1961), A unifying theory of high-latitude geophysical phenomena and geomagnetic storms, Canad. J. Phys., 39, pp. 1433-1464. Bruntz, R., R. E. Lopez, M. Wiltberger, and J. G. Lyon (2011a), Investigation of the viscous potential using an MHD simulation, J. Geophys. Res., in press. Bruntz, R., R. E. Lopez, S. K. Bhattarai, K. H. Pham, Y. Deng, Y. Huang, M. Wiltberger, and J. G. Lyon (2011b), Investigating the Viscous Interaction and its Role in Generating the Ionospheric Potential During the Whole Heliosphere Interval, submitted to J. Atmos. Solar Terr. Phys. Cowley, S. W. H. (1982), The Causes of Convection in the Earth’s Magnetosphere: A Review of Developments During the IMS, Rev. of Geophys. And Space Sci., 20(3), pp. 531-565. Dungey, J. W. (1961), Interplanetary magnetic field and the auroral zones, Phys. Rev. Lett., Vol. 6, pp. 47-48. Eastman, T. E., E. W. Hones Jr., S. J. Bame, and J. R. Asbridge (1976), The magnetospheric boundary layer: Site of plasma, momentum and energy transfer from the magnetosheath into the magnetosphere, Geophys. Res. Lett., 3(11), 685-688, doi:10.1029/GL003i011p00685. Lopez, R. E., R. Bruntz, E. J. Mitchell, M. Wiltberger, J. G. Lyon, and V. G. Merkin (2010), Role of magnetosheath force balance in regulating the dayside reconnection potential, J. Geophys. Res., 115, A12216, doi:10.1029/2009JA014597. Lyon, J. G., J. A. Fedder, and C. M. Mobarry (2004), The Lyon-Fedder-Mobarry (LFM) global MHD magnetospheric simulation code, J. Atmos. Sol. Terr. Phys., 66, 1333–1350, doi:10.1016/j.jastp.2004.03.020. Newell, P. T., T. Sotirelis, K. Liou, and F. J. Rich (2008), Pairs of solar wind‐magnetosphere coupling functions: Combining a merging term with a viscous term works best, J. Geophys. Res., 113, A04218, doi:10.1029/2007JA012825. Weimer, D. R. (2005), Improved ionospheric electrodynamic models and application to calculating Joule heating rates, J. Geophys. Res., 110, A05306, doi:10.1029/2004JA010884.

  16. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Conclusions • The viscous potential can be a significant fraction of the CPCP, even during strongly southward Bz. • Bruntz et al. [2011a] VP formula is based on ΣP = 10 mhos; WHI runs used F10.7 = 74 SFU. Scaling the former by γ = 1.542 gives good agreement with the potentials in the B0 run. • Scaling the Weimer [2005] CPCP by γ gives good agreement with the full LFM CPCP, even though γ is not directly based on either. This implies γ is more than a “fudge factor;” ionospheric conductivity is too low in LFM. Looking for a Post-doc? Let’s talk!

  17. The viscous interaction potential during the Whole Heliosphere Interval – one solar rotation R. Bruntz1, R. E. Lopez1, S. K. Bhattarai1, K. H. Pham1, Y. Deng1, Y. Huang1, M. Wiltberger2, and J. G. Lyon3 Department of Physics, University of Texas at Arlington National Center for Atmospheric Research, High Altitude Observatory Department of Physics and Astronomy, Dartmouth College Fall 2011 Texas APS/AAPT/SPS Meeting Texas A&M University – Commerce October 6-8, 2011 Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  18. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 To do Modify contents to match outline Re-do “LFM Output” images to include Earth

  19. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Solar Wind for DOY 85-90

  20. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  21. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  22. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  23. Observational results There is a suggestive trend in the measured PCP toward increasing viscous potential with increased solar wind density, for similar velocities. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011

  24. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Comparison of the CMIT CPCP, the full stand-alone LFM CPCP, and the B=0 stand-alone LFM CPCP.

  25. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Comparison of the CMIT CPCP and the stand-alone LFM CPCP.

  26. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Starting form of the two viscous potential formulations we used: • Newell et al. [2008]: • viscous interaction ~ n1/2V2 (no units) • Bruntz et al. [2011a]: • VP = (0.00431)n0.439V1.33 [kV]

  27. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 Calibrating the Newell et al. [2008] viscous scaling term • viscous interaction ~ n1/2V2 • => VP = νn1/2V2 • VP0 = νn01/2V02 • ν = [ VP0 / (n01/2V02) ]

  28. Fall 2011 Tx. APS/AAPT/SPS Meeting - Texas A&M Univ.-Commerce - Oct. 6-8, 2011 The modified viscous potential formulations: • Newell et al. [2008]: • VPB0 = νn1/2V2 [kV] (ν = 9.858×10-5) • Bruntz et al. [2011a]: • VPB0 = γVP • VPB0 = γ(0.00431)n0.439V1.33 [kV] • γ = 1.542

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