ULF Energy Transport Induced by Magnetospheric Boundary Oscillations Bill Lotko and Jeff Proehl Thayer School of Engineering Dartmouth College Boundary oscillations induce internal MHD waves Internal wave power is absorbed Characterize: Wave distribution Energy transport
6
Embed
ULF Energy Transport Induced by Magnetospheric Boundary Oscillations Bill Lotko and Jeff Proehl Thayer School of Engineering Dartmouth College Boundary.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
ULF Energy Transport Induced
by Magnetospheric Boundary Oscillations
Bill Lotko and Jeff Proehl Thayer School of EngineeringDartmouth College
Boundary oscillations induce internal MHD waves
Internal wave power is absorbed
Characterize:
Wave distribution
Energy transport
One-fluid, linear MHD
Cold plasma = 0 slow mode
Density
Dipole magnetic field
Boundaries L = 5, 10 and r = 2 RE
Radial boundary oscillation n = 1, m = 3, f = 6 mHz
Numerical solution, dissipation
Boundary-constrained, magnetic flux coordinates
Approach
mp E
3 6
0 L L R L rn(r,L)=n
v = 0
=
v
v
=
v = 0
Mode Structure v
v
b
b
b
1000
100
10
1
km/s
100
10
1
.1
nT
224
84
100
15
2
224
84
.5
.1
3
PHASE QUADRATURE
• Parallel – compare v and b
• Azimuthal – compare v and v
DIPOLE “LENS”
• Compressional signal
• Inner magnetosphere
• m 6
LARGE EQUATORIAL FLOWS
• v, 100 km/s at L = 7.5
Validation
100
50
0
GOES 7 – CANOPUS Mar 1990
% C
om
pA
zim
uth
, d
eg
90
-90
0 || B
φ
r
r
P +P
P +P +P
0 2 4 6
LFLR - LGOES
Ziesolleck et al. ’96
100 nT
b
b
2 nT
FLR
MP
Wave Energy Flux
9 W/m2
535 W/m2 36 W/m2
W/m2
1000
100
10
1
Compressional dipole lensEvanescent decay is counteracted by magnetic focusing at low m Outer magnetospheric, dayside Pc 5 waves can drive plasmaspheric cavity modes
Collective energy transportMode distribution + relative phases power flow and group propagation