Localized Thermospheric Energy Deposition
Observed by DMSP Spacecraft
D. J. Knipp1,2,
1Unversity
of Colorado, Boulder, CO, USA
2High Altitude Observatory, NCAR Boulder, CO, USA
with contributions from:
Y. Deng, L. Kilcommons,
W. Li, J.Raeder, G. Crowley
Data provided by E. Sutton, F Rich, G Wilson B Anderson
Outline
• Dayside Energy Deposition Background
– Influence of IMF By on Poynting flux
– Influence of low energy electrons
• Local Combined influence of Poynting flux
and Particles (outside of standard indices)
• Future work
– Global Combined Poynting Flux and Particle Flux
• Observations
• Models
CHAMP Cusp Neutral Density Enhancement (2002-2005)
North
South
Rentz 2009 and Forster, 2010
Poynting Flux -Neutral Density Comparisons
Poynting
Flux
mW/m2
Southern
Hemisphere
Nov 2001Feb 2002
Slow Flow
CMEs &
Transients
High Speed
Flow
CHAMP
Neutral
Density
X 10--11kg/m3
Ionosphere-Thermosphere Energy Dissipation
~ 75%
~ 25%
Courtesy of Jeff Thayer, CU
Poynting Vector and Particles from
Defense Meteorological Satellite Program S/C
DMSP instruments sense
Electric and Magnetic
Fields
Y
ee
-
Spacecraft track
X
Z
S
 E  B DMSP Horizontal /  0
S||
 ( E xB y  E yBx ) /  0
where
E   V  B IGRF
and
B DMSP Horizontal  B DMSP  B Main
DMSP Poynting Flux
Changing IMF By
Poynting flux exceeds that reported for
intense substorms within a superstorm
Knipp et al, GRL, 2011
Flank Reconnection Contributes to Neutral Density Enhancement
IMF By is large Northern Hemisphere Example--Cont
DMSP Poynting Flux
Neutral Density from TIEGCM
Joule Heating from AMIE
Localized
Energy
Associated with
Neutral Density
Upheaval
Crowley et al., 2010
TIEGCM Neutral Density
compared to CHAMP satellite
Flank Reconnection Contributes Poynting Flux when
IMF By is large Northern Hemisphere Example 2
IMF By + Nov 7 2004
Li et al (2011)
Southern
Hemisphere
Northern
Hemisphere
DMSP Extreme Poynting Flux
|By| > 10
Bz < 0
mW/m2
mW/m2
By-N By+S
2000-2005
Each dot represents the maximum value of the of the pass
Colored dots show Poynting flux in excess of 75 mW/m2
~ 1500 passes are shown
By+N By- S
DMSP Extreme Poynting Flux
|By| > 10
Bz >0
mW/m2
mW/m2
By-N By+S
2000-2005
Each dot represents the maximum value of the of the pass
Colored dots show Poynting flux in excess of 75 mW/m2
~ 1500 passes are shown
By+N By-S
Field Aligned Currents in the Cusp
Strangeway et al., 2005
DMSP Poynting Flux Bz < 0
Poynting Flux mW/m2
-10 nT < Bz< -5 nT
|By| < 5 nT
Poynting Flux mW/m2
Fewer extreme values;
Maybe associated with
flow channel persistence
-5 nT < Bz< 0 nT
|By| < 5 nT
Effects of Large East West IMF on the Cusp
OPENGGCM MHD models and DMSP data show that east-west IMF
promotes flank and or lobe merging that maps to cusp regions
Movement of the open field lines resulting from this reconnection
produces a pair of neighboring opposite FACs in the dayside
ionosphere cusp region
Closure of the FACs results in Joule heating in the ionospheric flow
channel between the currents
FAC locations are mainly controlled by the IMF clock angle.
High speed solar wind flow enhances the Joule heating
Joule heating in narrow, elongated channels may exceed 170mW/m2
When IMF By > 10 nT typical values of Poynting flux ~ 75mW/m2
Soft Particle Effects in Cusp
DMSP Medium and Low Energy Particles (2004
Location of maximum energy deposition during each polar pass
electrons 962-679 eV
462-317 eV
213-145 eV
100- 68 eV
46-32 eV
electrons 962-679 eV
462-317 eV
213-145 eV
100- 68 eV
46-32 eV
North
5-10nT
By –
Bz -
South
5-10nT
By +
Bz-
Particles with energies < 300 eV often ignored
Poynting Flux-Density Relations in the Cusp
At 400 km:
29%
increase in
Tn
At 400 km:
rise and fall
of neutral
mass
At 200 km:
7% decrease
in ρn
At 400 km:
31%
increase in
ρn
Difference in the thermosphere 3 hours after adding in the Poynting flux ( 75 mW/m2)
GTM simulation by Deng et al 2011
Soft Particle Effects in Cusp
At 200 km:
2% decrease
in ρn
At 400 km:
35%
increase in
ρn
Difference in the thermosphere 3 hours after adding in the soft particle flux
(100 eV, 2 mW/m2)
GITM simulation (Deng et al. 2011)
Poynting Flux and Soft Particle Effects in Cusp
At 200 km:
4% decrease
in ρn
At 400
km: 50%
increase
in ρn
Difference in the thermosphere 3 hours after adding in Poynting Flux and the soft
particle flux
(PF = 75 mW/m2, 2keV 0.3 mW/m2, 100 eV, 2 mW/m2)
GITM simulation (Deng et al. 2011)
Poynting Flux and Soft Particle
Effects in Cusp
50% increase is < 31%+35%+5%, because the Poynting Flux and
Particle Precipitation Effects are not Co-located
~50% neutral density enhancement is consistent with CHAMP obs
Deng et al. 2011
Magnetosphere-Ionosphere Thermosphere Cusp
Energy
Global Currents
North
South
Summary and Conclusions
• Persistent near cusp CHAMP neutral density
enhancement
– Cusp Enhanced Poynting Flux (order of magnitude)
• IMF By, solar wind flow speed & variability, pressure
– Cusp Soft Particle Precipitation
• IMF, solar wind flow speed & variability, pressure
• These are NOT well described by geomagnetic
indices
• Global observations and modeling are key to
future progress