Extreme Poynting Flux
Over the Polar Cap Region
Mike Cook
Delores Knipp
Liam Kilcommons
Overview
!  Big Picture and goal of my project
!  Poynting Flux
!  Southward IMF (generally well understood)
!  Methodology
!  Northward IMF (remotely understood but not clear)
!  Case Studies
!  Conclusion
!  Questions
Big Picture
!  From DMSP, determine where Poynting
Flux (electromagnetic energy) is being
deposited in reference to the auroral
boundary.
!  Determine the locations, associations and
drivers of extreme Poynting Flux in or
around the polar cap region.
!  Improve the estimation of the local and
large-scale electric and magnetic field
estimates to provide estimates of the
energy extracted from all energy sources
to power the upper atmosphere.
What is Poynting Flux?
•  Poynting Flux is electromagnetic-wave energy
passing through some surface.
•  Poynting Flux is derived, not a direct measure from
spacecraft.
Generic Southward IMF
Southward, Eastward and Westward
IMF Convection Patterns
E PF Note that the Hall currents are opposite in direc6on to the convec6on because they are carried by the electrons B Weimer, D. R. (2005), Improved ionospheric electrodynamic models and applica6on to calcula6ng Joule hea6ng rates, J. Geophys. Res., 110, A05306, doi:10.1029/2004JA010884. Methodology
!  DMSP F13 F15 F16.
!  How Poynting Flux is derived.
!  12 separate cases.
!  Timing of events.
Generic Northward IMF
Northward IMF Convec6on Cycle 1 6 2 5 3 4 Northern Hemisphere
Events
May
th
15
2005 Event
August 24 2005 Event
Southern Hemisphere
Events
November 24th 2001 Event
December 15 2001 Event
Drivers and Associations to
Extreme Poynting Flux
Mach # 0 0.00 2.00 4.00 6.00 8.00 10.00 Poyn%ng Flux (mW/m^2) -­‐20 y = 3.899x -­‐ 63.543 R² = 0.06611 -­‐40 -­‐60 Mach # -­‐80 Linear (Mach #) Linear (Mach #) -­‐100 -­‐120 -­‐140 -­‐160 Alfven Mach # Mag IMF Bx 0 0 5 10 15 20 25 30 35 40 Poyn%ng Flux (mW/m^2) -­‐20 -­‐40 -­‐60 -­‐80 y = -­‐1.5057x -­‐ 32.346 R² = 0.16412 -­‐100 -­‐120 -­‐140 -­‐160 IMF Bx (nT) Mag IMF Bx Linear (Mag IMF Bx) Solar Wind Speed 0 0 200 400 600 800 1000 Poyn%ng Flux (mW/m^2) -­‐20 -­‐40 -­‐60 -­‐80 y = -­‐0.0932x + 8.7008 R² = 0.20978 Linear (Speed) -­‐100 -­‐120 -­‐140 -­‐160 Speed Solar Wind Speed E SolarWindTrans 0 0.00 5.00 10.00 15.00 20.00 Poyn%ng Flux (mW/m^2) -­‐20 -­‐40 y = -­‐5.3459x -­‐ 2.8035 R² = 0.47085 -­‐60 -­‐80 Eswtrans Linear (Eswtrans) -­‐100 -­‐120 -­‐140 -­‐160 Ey: Solar Wind Electric Field from Bsw trans*Vsw Conclusions
!  Poynting flux deposition during northward IMF can be
extreme.
!  The primary responding parameter is Low Earth Orbit
(LEO) Delta By (eastward dB) associated with field
aligned currents.
!  An external driver is the fast delivery of the transverse
IMF that has a good correlation with Poynting Flux.
!  The next step in this project will be to look at a lot
larger sample size of events that meet our
parameterizations.
A Huge Thank You
!  Delores Knipp
!  Liam Kilcommons
!  Erin Wood
!  DMSP data providers
!  NASA
!  OMNIWeb
Questions?