The Direct and Indirect Drivers of Space
Weather
Jonathan Rae
APL
NASA
Causes and consequences of space weather
What is Space Weather?
• Changing
conditions in
near-Earth space
due to space
disturbances
• One of the most
exciting natural
laboratories
available to
study….
• Practical aspects;
understand
conditions that
lead to socioeconomic impact
Space Weather drivers
Space Weather consequences
Atmospheric Losses
Rad
Belts
Why should you care?
• Pick your favourite technology
–
–
–
–
Telecommunication
GPS
Oil pipelines
Power grids
• Imagine it didn’t work (or it cost
double)
What are the space weather effects on us?
Space Weather disrupts and destroys
1989
1994
1997
2003
2005
2010
Hydro-Quebec blackout
Canadian ANIK E-1 and E-2 satellites lost
(CAD$200m)
AT&T pager blackout
33 separate satellite anomamlies reported during a
moderate geomagnetic storm
GPS positions during storms ~10s metres out
Galaxy-15 telecom satellite loss
Hutchins (2012)
A wide range of induced
effects and variability
Space Weather disrupts and destroys
1997
2003
2005
2010
Hydro-Quebec blackout
Canadian ANIK E-1 and E-2 satellites lost
(CAD$200m)
AT&T pager blackout
33 separate satellite anomamlies reported during a
moderate geomagnetic storm
GPS positions during storms ~10s metres out
Galaxy-15 telecom satellite loss
1024
800
E > 2 MeV Electrons
2.5 < L < 6.5
700
1023
600
1022
500
1021
400
V
27-day Running Averages
sw
300
1992
1995
1998
Year
[OMNITAPE]
1020
2001
Radiation Belt Index
Solar Wind Speed [km/s]
1989
1994
Space Weather disrupts and destroys
1989
1994
1997
2003
2005
2010
Hydro-Quebec blackout
Canadian ANIK E-1 and E-2 satellites lost
(CAD$200m)
AT&T pager blackout
33 separate satellite anomamlies reported during a
moderate geomagnetic storm
GPS positions during storms ~10s metres out
Galaxy-15 telecom satellite loss
Spacecraft Anomalies: October-November 2003
POLAR
Genesis
ADEOS-2, Stardust, Chandra,
Various GOES
RHESSI
KODAMA, Mars Odyssey
NOAA-17
INTEGRAL, Chandra, SMART-1
Star Tracker Anomalies at GEO
1982
1981
1980
25
Geostationary Orbit
Star Tracker Upsets
1.4 - 2.0 MeV
Electrons
Electrons/cm 2-s-sr-keV
20
15
10
5
0
600
700
800
900
1000
Days from 1 January 1979
Baker
(1987)
1100 et al.
1200
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
“This
year,ofafter
Aurora - Roman
goddess
dawn, Borealis - Greek northern winds
Christmas,
on a Monday
Jean Jacques
d'Ortous de Mairan
publishes first textbook devoted to
aurora; proposes
mingling
of Earth
and
solar atmospheres/zodiacal light;
night,
at the
first
sleep,
suggests sunspot
correlation,
existence
of southern aurora
was the
heaven
on the
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae northern hemisphere all as
if itproposes
were burning
fire; so
Leonhard Euler
escaping particles
at the poles
that
allofwho
saw it were
so Capt. Don Ulloa)
Mairan obtains
report
1745 southern
aurora (from
William Watson
invents discharge
leads to electrical discharge
dismayed
as theytube;
never
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
were before.”
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
30,000 BC
5th c. BC
585 AD
1131
1575
ca. 1620
1733
1741
1746
1750
1752
1790
1817
1819-47
Cro-Magnon cave-paintings: "macaronis" earliest depiction of aurora?
Hippocrates suggests aurora is caused by reflected sunlight
Gregory of Tours describes aurorae as natural phenomena (not
supernatural)
Record of an auroral sighting in the Anglo Saxon Chronicle
Cornelius Gemma publishes first scientific illustration of aurora
Galileo Galilei or Pierre Gassendi coin name "aurora borealis"
Aurora - Roman goddess of dawn, Borealis - Greek northern winds
Jean Jacques d'Ortous de Mairan publishes first textbook devoted to
aurora; proposes mingling of Earth and solar atmospheres/zodiacal light;
suggests sunspot correlation, existence of southern aurora
Anders Celsius and Olof Hiorter note coincidence of magnetic storms and
aurorae
Leonhard Euler proposes escaping particles at the poles
Mairan obtains report of 1745 southern aurora (from Capt. Don Ulloa)
William Watson invents discharge tube; leads to electrical discharge
theories of aurora by Mikhail Lomonosov and Ben Franklin among others
Henry Cavendish measures height successfully, 50 - 70 miles high
Jean Batiste Biot proves aurora is self luminous (not reflected sunlight)
John Franklin notes decrease in auroral frequency toward pole
Space Weather through the ages
1859
1861
1868
1903
1900-13
1950s
1953
1958
1974
1981
2001
Carrington solar flare; brilliant aurora occurs evening of the 2nd Sept
Balfour Stewart explains the Carrington Flare, auroral and magnetic
disturbance; first observations of waves in the Earth’s magnetic field
Boston Traveler, Sept. 2, 1859:
Anders Angstrom defines auroral colours
Kristianoperator
Birkeland
existence
of large
currents
Boston
(toinfers
Portland
operator):
"Please
cut off associated
your batterywith
[power
aurora
(auroral
electrojets)
source] entirely for fifteen minutes."
Birkelandoperator:
conducts
demonstrations
with
physical model terrella
Portland
"Will
do so. It is now
disconnected."
Boston:
is disconnected,
arewind
working
with the
auroraltails
current.
Ludwig "Mine
Biermann
discovered and
the we
solar
studying
cometary
How
do you receive
my writing?"
Jim Dungey
proposed
that the solar wind could penetrate the Earth’s
Portland:
"Better via
thanmagnetic
with our batteries
on. - Current comes and goes
magnetosphere
reconnection
gradually."
Discovery of the Van Allen Radiation Belts by James Van Allen, 1964
Boston: Syun
"My current
is very
strongauroral
at times,
and we
work better without the
Akasofu
connects
bursts
to can
magnetospheric
batteries,
as the aurora seems to neutralize and augment our batteries
substorms
alternately,
making
current
too strong
at times forCurents"
our relay magnets. Suppose
Triad satellite
provides
evidence
for "Birkeland
we
work without
batteries
whileprovides
we are affected
this trouble."
Dynamics
Explorer
1 satellite
first fullbyimage
of auroral oval
Portland: "Very well. Shall I go ahead with business?"
Polar captures conjugate aurora
Boston: "Yes. Go ahead."
Space Weather through the ages
1859
1861
1868
1903
1900-13
1950s
1953
1958
1964
1974
1981
2001
Carrington solar flare; brilliant aurora occurs evening of the 2nd Sept
Balfour Stewart explains the Carrington Flare, auroral and magnetic
disturbance; first observations of waves in the Earth’s magnetic field
Anders Angstrom defines auroral colours
Kristian Birkeland infers existence of large currents associated with
aurora (auroral electrojets)
Birkeland conducts demonstrations with physical model terrella
Ludwig Biermann discovered the solar wind studying cometary tails
Jim Dungey proposed that the solar wind could penetrate the Earth’s
magnetosphere via magnetic reconnection
Discovery of the Van Allen Radiation Belts by James Van Allen
Syun Akasofu connects auroral bursts to magnetospheric substorms
Triad satellite provides evidence for "Birkeland Curents"
Dynamics Explorer 1 satellite provides first full image of auroral oval
Polar captures conjugate aurora
Space Weather through the ages
1859
1861
1868
1903
1900-13
1950s
1953
1964
1974
1981
2001
Carrington solar flare; brilliant aurora occurs evening of the 2nd Sept
Balfour Stewart explains the Carrington Flare, auroral and magnetic
disturbance; first observations of waves in the Earth’s magnetic field
Anders Angstrom defines auroral colours
Kristian Birkeland infers existence of large currents associated with
aurora (auroral electrojets)
Birkeland conducts demonstrations with physical model terrella
Ludwig Biermann discovered the solar wind studying cometary tails
Jim Dungey proposed that the solar wind could penetrate the Earth’s
magnetosphere via magnetic reconnection
Syun Akasofu connects auroral bursts to magnetospheric substorms
Triad satellite provides evidence for "Birkeland Curents"
Dynamics Explorer 1 satellite provides first full image of auroral oval
Polar captures conjugate aurora
Space Weather through the ages
1859
1861
1868
1903
1900-13
1950s
1953
1958
1964
1974
1981
2001
Carrington solar flare; brilliant aurora occurs evening of the 2nd Sept
Balfour Stewart explains the Carrington Flare, auroral and magnetic
disturbance; first observations of waves in the Earth’s magnetic field
Anders Angstrom defines auroral colours
Kristian Birkeland infers existence of large currents associated with
aurora (auroral electrojets)
Birkeland conducts demonstrations with physical model terrella
Ludwig Biermann discovered the solar wind studying cometary tails
Jim Dungey proposed that the solar wind could penetrate the Earth’s
magnetosphere via magnetic reconnection
Discovery of the Van Allen Radiation Belts by James Van Allen
Syun Akasofu connects auroral bursts to magnetospheric substorms
Triad satellite provides evidence for "Birkeland Curents"
Dynamics Explorer 1 satellite provides first full image of auroral oval
Polar captures conjugate aurora
Space Weather through the ages
Carrington solar flare; brilliant aurora occurs evening of the 2nd Sept
Balfour Stewart explains the Carrington Flare, auroral and magnetic
disturbance; first observations of waves in the Earth’s magnetic field
1868
Anders Angstrom defines auroral colours
1903
Kristian Birkeland infers existence of large currents associated with
aurora (auroral electrojets)
1900-13
Birkeland conducts demonstrations with physical model terrella
1950s
Ludwig Biermann discovered the solar wind studying cometary tails
1953
Jim Dungey proposed that the solar wind could penetrate the Earth’s
magnetosphere via magnetic reconnection
1958
Discovery of the Van Allen Radiation Belts by James Van Allen
1964
Syun Akasofu connects auroral bursts to magnetospheric substorms
1974
Triad satellite provides evidence for "Birkeland Curents"
1981
Dynamics Explorer 1 satellite provides first full image of auroral oval\
2001
Polar captures conjugate aurora
1859
1861
25
Space Weather through the ages
1859
1861
1868
1903
1900-13
1950s
1953
1958
1964
1974
1981
2001
Carrington solar flare; brilliant aurora occurs evening of the 2nd Sept
Balfour Stewart explains the Carrington Flare, auroral and magnetic
disturbance; first observations of waves in the Earth’s magnetic field
Anders Angstrom defines auroral colours
Kristian Birkeland infers existence of large currents associated with
aurora (auroral electrojets)
Birkeland conducts demonstrations with physical model terrella
Ludwig Biermann discovered the solar wind studying cometary tails
Jim Dungey proposed that the solar wind could penetrate the Earth’s
magnetosphere via magnetic reconnection
Discovery of the Van Allen Radiation Belts by James Van Allen
Syun Akasofu connects auroral bursts to magnetospheric sub-storms
Triad satellite provides evidence for "Birkeland Curents"
Dynamics Explorer 1 satellite provides first full image of auroral oval
Polar captures conjugate aurora
26
How large is the space weather domain?
Back to the Physics of Space Weather
“My God, space is radioactive!”
(Ernest Ray, 1958) • Intense belts of radiation surrounding
the Earth – The Van Allen Radiation
Belts
• There for no good reason! Why?
• 39 astronauts have developed
cataracts in later life, 36 flew in high
radiation missions
(left to right) William H. Pickering,
James A. Van Allen, and Wernher
von Braun
Radiation Belts
• Discovery of the radiation belts by
James Van Allen and coworkers
nearly 60 years ago.
• Radiation belt dynamics remain an
enigma.
– What causes relativistic particle
acceleration?
– What causes relativistic particle loss?
– What constraints can be placed on radiation
belt processes from ground-based and
satellite observations?
– What effects do the radiation belts have on
ground, air and space-based infrastructure?
Radiation Belt Morphology: Inner and Outer
Zones
Radiation Belt Morphology: Inner and Outer
Zones
Radiation Belt Morphology constantly in flux…
Reeves et al. [2003]
And never responds the same way to the
solar wind
• Three different responses
• Or to put it another way: Random
Reeves et al. [2003]
And never responds the same way to the
solar wind
Not just two belts either…..
Treating the Radiation Belts Holistically
Outward
Precipitation
Substorm
Injection
Horne [2007]
Local
Acceleration
Understanding all sources and sinks are a must, otherwise not a unique
solution
Charged Particle Motion and Adiabatic
invariants
• Particles trapped by magnetic field
• Execute gyro, bounce and drift motions
– Gyro ~millisecond, bounce ~ 0.1-1
second, drift ~1-10 minutes
• Invariants hold for timescales that are
long compared to the gyration, drift,
bounce
• Conservation results in changes in
flux, but no net acceleration or loss
W

B
J   p|| ds
   BdS
And yet the radiation belts exist…and get hotter
and cooler
Charged Particle Motion and Adiabatic
invariants
• Acceleration requires violating one or
more invariants
– Sudden changes of field configurations
– Small but periodic variation of field
configurations
– E, B fields at frequencies comparable
to drift, bounce and cyclotron
frequencies
W

B
J   p|| ds
   BdS
So what causes the electrons to break
invariants?
– Acceleration: large- and smallscale recirculations, heating by
Whistler waves, radial diffusion by
ULF waves, cusp source,
substorm injection, sudden
impulse of solar wind pressure and
etc.
– Loss: pitch angle diffusion,
Coulomb collision, and
Magnetopause shadowing.
– Transport: Radial diffusion by
ULF waves, rapid magnetic field
topology changes due to
compressions
Where do these processes operate?
Or more simply, some kinds of….
So what processes are important?
• All of them?
…..maybe
• Difficulties to differentiate the mechanisms:
–
–
–
–
–
Lack of Measurements
Lack of an accurate magnetic and electric field model to follow e- trajectory
Converting particle flux to distribution function is tricky
Need better understanding of wave-particle interactions
Computational resources
Introducing the old school: the (electron)
cyclotron resonance
• For resonance with electrons,
wave frequency is Doppler
shifted along B
• Waves must propagate in
opposite direction than
electrons
• Very efficient energy exchange
• Breaking 1st and 2nd invariant:
• acceleration and loss through
violation of different invariants
changing energy or pitch angle
Introducing the nearly old school: the (ion)
cyclotron resonance
• For resonance with electrons,
wave frequency is Doppler
shifted along B
• Waves must propagate in
same direction than electrons
• Very efficient energy exchange
• Can loss through violation of
different invariants changing
pitch angle
Old School Cyclotron Resonance Pros
• Highly efficient energy transfer
• Theoretically appealing
universal solution
• Can cause acceleration in
energy
• Can cause loss through pitch
angle changes
Old School Cyclotron Resonance Cons
• Small amplitude waves contain
small amounts of energy
• Dependent on plasma
conditions inside
magnetosphere
• Azimuthally localized
• Radially localized
Introducing the new kids on the block: Ultra-Low
Frequency Waves
•
Energy gain is a function of
electric field and drift velocity
 
dW
 q vD  E
dt
How are these waves generated?
Radiation Belt fluxes are tied to solar wind speed
Solar wind velocity correlated well with radiation belt intensity, so
Kelvin-Helmholtz is a great candidate
The New Kid ULF Pros
• Global-scale
• Huge energy
• Can transport and accelerate a
wide range of energies
• Fluxes, waves and solar wind
speeds are all correlated
The New Kid Cons
• Not thought to provide fast
acceleration so may not be a
linear response
• Can’t cause loss
• Can’t cause growing electron
peaks in the radiation belts by
themselves
Does any of this physics work in real life?
• Both mechanisms
proposed to explain the
third radiation belt
“discovered” by Van
Allen Probes
Shprits et al. 2013 Nature Physics
Case A:
Explaining
Storm-Time
dynamics via
cyclotron
resonance ONLY
Case A: Sometimes though…..
http://www.fp7-spacecast.eu/
Mann et al. soon to be Nature Physics
Case B:
A simpler first
principles
radiation belt
model using
ULF waves
ONLY
Mann et al. soon to be Nature Physics
Case B:
That also
works at
more than
one energy
So it’s complicated. But what drives this
system?
•
•
•
Some of these models have such good agreement for specific case studies.
Are we reverse engineering the answer?
If we don’t know the answer, can we still predict the right physics?
•
Probably not….yet
•
•
Not all magnetic storms or fast solar wind streams result in a net electron flux
enhancement.
Not all result in a decrease either
•
We know all of these physical processes contribute.
•
Unravelling which bits do what, how and when is where we’re at.
Putting together (most of) Current Theory
and Observations
Why should you care about space weather?
• Pick your favourite technology
–
–
–
–
Telecommunication
GPS
Oil pipelines
Power grids
• Imagine it didn’t work (or it cost
double)
• Also it’s really interesting science!