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  B  

PF  

Note  that  the  Hall  currents  are  opposite  in  direc6on  to  the  convec6on  because  they  are  carried  by  the  electrons    

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

1  

2  

3  4  

5  

6  

Northward  IMF  Convec6on  Cycle  

The  ionospheric  “footprints”  of  the  convec6ng  magne6c  field  lines  for  northward  IMF  

Northern Hemisphere Events

May 15th 2005 Event

August 24 2005 Event

Southern Hemisphere Events

November 24th 2001 Event

December 15 2001 Event

Drivers and Associations to Extreme Poynting Flux

y  =  3.899x  -­‐  63.543  R²  =  0.06611  

-­‐160  

-­‐140  

-­‐120  

-­‐100  

-­‐80  

-­‐60  

-­‐40  

-­‐20  

0  0.00   2.00   4.00   6.00   8.00   10.00  

Poyn%n

g  Flux  (m

W/m

^2)  

Alfven  Mach  #  

Mach  #  

Mach  #  

Linear  (Mach  #)  

Linear  (Mach  #)  

y  =  -­‐1.5057x  -­‐  32.346  R²  =  0.16412  

-­‐160  

-­‐140  

-­‐120  

-­‐100  

-­‐80  

-­‐60  

-­‐40  

-­‐20  

0  0   5   10   15   20   25   30   35   40  

Poyn%n

g  Flux  (m

W/m

^2)  

IMF  Bx  (nT)  

Mag  IMF  Bx  

Mag  IMF  Bx  

Linear  (Mag  IMF  Bx)  

y  =  -­‐0.0932x  +  8.7008  R²  =  0.20978  

-­‐160  

-­‐140  

-­‐120  

-­‐100  

-­‐80  

-­‐60  

-­‐40  

-­‐20  

0  0   200   400   600   800   1000  

Poyn%n

g  Flux  (m

W/m

^2)  

Solar  Wind  Speed  

Solar  Wind  Speed  

Speed  

Linear  (Speed)  

y  =  -­‐5.3459x  -­‐  2.8035  R²  =  0.47085  

-­‐160  

-­‐140  

-­‐120  

-­‐100  

-­‐80  

-­‐60  

-­‐40  

-­‐20  

0  0.00   5.00   10.00   15.00   20.00  

Poyn%n

g  Flux  (m

W/m

^2)  

Ey:  Solar  Wind  Electric  Field  from    Bsw  trans*Vsw  

E  SolarWindTrans  

Eswtrans  

Linear  (Eswtrans)  

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?