Effects of Coronal Mass Ejections and Solar Wind Streams on the Earth’s

Radiation BeltsD.N. Baker, S. Kanekal, X. Li, S. Elkington

Laboratory for Atmospheric and Space Physics

Department of Astrophysical and Planetary Sciences

University of Colorado - Boulder

LWS CDAW Workshop 14 March 2005

Adiabatic Invariants

• M: perpendicular motion

• K: parallel motion

• L: radial distance of eq-crossing in a dipole field

Associated with each motion is a corresponding adiabatic invariant:

If the fields guiding the particle change slowly compared to the characteristic motion, the corresponding invariant is conserved.

•Gyro: M=p2/2m0B•Bounce: K•Drift: L

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The Earth’s Radiation Belts

Contours of the omnidirectional flux (particles per square centimeter per second) of protons with energies greater than 10 MeV

Contours of the omnidirectional flux of electrons with energies greater than 0.5 MeV

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TOPEX (1992-1998) and TERRA-MODIS (2001)

The South Atlantic Anomaly Region

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Solar Activity Cycle

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The Disturbed Solar Wind: Coronal Mass Ejections (CMEs)

• Occur most often near the peak of the Sun’s 11-year activity cycle

• Propel >109 tons of matter into interplanetary space

• Can travel at speeds exceeding 2000 km/s

• Drive interplanetary shocks• Can trigger geomagnetic

storms when they impact Earth’s magnetosphere

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Coronal Mass Ejection - Earth ImpactC

ourt

esy

of N

AS

A

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Impulsive Injection Due to Shock Wave

[Li et al., 1993]

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Outer Belt Electrons: 1992-2002

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Mapping of the Radiation Belt

SAMPEX: 18 August 1993

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Dynamic Radiation Belts: 1993-1995

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Acceleration by Radial Transport

30

L

MBW

Nonrelativistically, and in a dipole,

or

0

3

0

2

2 B

WL

Bm

pM

so transport in L while conserving M willnecessarily lead to change in energy, W.

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Transport in M, K: Local Heating

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Local Heating Example:Resonant Interactions with VLF Waves

• Whistler mode chorus at dawn combined with EMIC interactions heat and isotropize particles

• Leads to transport in M, K, and L

Summers et al. (JGR 103, 20487, 1998) proposed that resonant interactions with VLF waves could heat particles:

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MHD Simulations of ULF Power, 09/24/1998

• ULF power in MHD shows expected radial, frequency dependence

• Azimuthal dependence: frequently see structure in local time

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Shear Waves and Particle Acceleration

• Limited local time: propagating waves dusk and counterpropagating waves dawn still lead to energization

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MHD Simulation of a Strong Storm

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MHD/Particle Simulations of Energetic Electron Trapping

• 60 keV test electrons, constant M

• Started 20 RE downtail, 15s intervals

• Evolves naturally under MHD E and B fields

• Removed from simulation at magnetopause

• Color coded by energy

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LWS CDAW Workshop 14 March 2005High-Energy Electrons

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High-Energy Electrons: Deep-Dielectric Charging

3. Influx of electrons increases to levels higher than the leakage rate

2. Electrons slowly leak out of the insulator

1. Electrons bury themselves in the insulator 4. Electrons build up faster than they leak off

5. Discharge (electrical spark) that damages or destroys the material

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Star Tracker Anomalies at GEO

0

5

10

15

20

25

600 700 800 900 1000 1100 1200

Ele

ctro

ns/c

m2-s

-sr-

keV

Days from 1 January 1979

1.4 - 2.0 MeV Electrons

Geostationary OrbitStar Tracker Upsets

1980 1981 1982

Baker et al. (1987)

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Probability of discharges goes up dramatically with increasing electron fluence.

Anomalies Due to Dielectric Charging

Vampola (1977)

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1020

1021

1022

1023

1024

Radiation Belt Content Index

Tota

l Num

ber

of E

lect

rons

Year92 94 96 98 00 02

2.5 < L < 6.5E > 2 MeV

[Derived from SAMPEX / ELO]

Radiation Belt Content Index

• Gives a single “Radiation Belt Electron content” Index (RBI)

• Idea introduced in Baker et al. (1999)

• Integrates over energy spectrum and 2.5 < L < 6.5

1019

1020

1021

1022

1023

1024

.01 .1 1 5 10 20 30 50 70 80 90 95 99 99.9 99.99

Cumulative Probability

Rad

iatio

n B

elt I

ndex

Percent

Log-normal Gaussian Fit

Probability Distribution2.5 < L < 6.5 [ Derive from SAMPEX]

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300

400

500

600

700

800

1020

1021

1022

1023

1024

Sol

ar W

ind

Spe

ed [k

m/s

] Radiation B

elt Index

Year

1992 1995 1998 2001

E > 2 MeV Electrons2.5 < L < 6.5

Vsw

[OMNITAPE]27-day Running Averages

RBI-Solar Wind Speed Comparison

• Many operational anomalies in 1994 period

• Late 1993 and early 1994 were remarkable times for VSW

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ANIK Failures: Deep-Dielectric Charging

1020

1021

1022

1023

1024Total Radiation Belt Content Index

Tota

l Num

ber

of E

lect

rons

Year

1992 1994 1996 1998 2000 2002

E > 2 MeV[Derived from SAMPEX / ELO] 2.5 < L < 6.5

27-day Running Average

ANIK Anomalies

ANIK/Intelsat failures in January1994 occurredduring the highestradiation beltcontent intervalof the last decade

LWS CDAW Workshop 14 March 2005

The RBI Allows Averaging and Superposition

• Builds on idea of radiation belt “coherence”

• Annual and seasonal averaging is readily done

• Gives a true global view

0

2

4

6

8

10

12

14

16

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Nu

mb

er o

f E

lect

ron

s (

X 1

0-2

2)

Year

E > 2 MeV 2.5 < L < 6.5Outer Radiation Belt

2003 2005 2007 2009 2011

Years of Next Cycle (+ 11 Years):

0.0

0.5

1.0

1.5

2.0

Seasonal Average Fluxes : 1992 - 1999

No

rmai

lize

d E

lec

tro

n F

lux

February - April

May - July

August -October

November - January

SAMPEX Electrons 2.5 < L < 6.5 2 - 6 MeV

Spring

Summer

Fall

Winter

Baker et al., GRL (1999)

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10-1

100

101

100

101

102

1992 1993 1994 1995 1996 1997 1998 1999

Annual Relativistic Electron Acceleration Efficiency

Pow

er [x

10

-9 W

] Efficiency [x 10

-3]

Year

Electron (E > 0.5 MeV) Power 2.5 < L < 6.5

Solar Wind Input Power

( < > x 10-2 )

Relativistic ElectronProduction Efficiency

Radiation Belt Content : POLAR/SAMPEX

Baker et al., JGR (2001)

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October 2003 Events

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The Halloween Storm in the Heliosphere

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D. N

. Bak

er e

t al.,

Nat

ure,

16

Dec

200

4

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KODAMA, Mars Odyssey

Spacecraft Anomalies: October-November

Genesis

ADEOS-2, Stardust, Chandra, Various GOES

RHESSI INTEGRAL, Chandra, SMART-1

NOAA-17

POLAR

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Day-to-Day Variation of the Radiation Belts

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Selected Days: Outer Belt Properties

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30.4 nm EUV

(Cou

rtes

y of

J. G

olds

tein

)

Resonant Scattering

Plasmasphere

He+ 15%

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EUV Images of the Plasmasphere

Plasmasphere

He+ 15%

plasmasphere

Global EUV He+ Image

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Extreme Plasmasphere Erosion

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D. N. Baker et al., Nature, 16 Dec 2004

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Regions of Wave-Particle Interactions

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X-28 Class Flare

SEP

Fast CME, 2657 km/s

Glancing Blow

Largest Flare in Recorded History, Extremely Fast CME - Narrow Miss at Earth