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Solar-Terrestrial Relations

• The sun can influence the Earth in several ways
• Evolutionary changes
• Luminosity variations (spots, plage)
• Particles (flares, solar wind)

1 Occurs on timescales of 109 years, so only 2
and 3 are important for humans
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I. Solar Activity and Climate Changes
The solar irradiance change by no more than
0.10.3 during the sunspot cycle. What is the
corresponding temperature change at the Earth?
0.07
Lets take the solar irradiance changes of the
last 30 years which gives DL 0.00073
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Intercepted flux, Fin radiated flux, Fout
DT constants x (1/4) L3/4 DL
Naively we would expect that solar activity has
little influence on the Earths climate. But the
real story is different.
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Evidence for the influence of Solar Activity on
Climate
1 The Maunder minimum coincided with the Little
Ice Age in Europe. Baliunas and Jastrow estimate
that the solar irradiance during the Maunder
minimum was about 0.4 less than it is now (based
on studies of solar-type stars). This could
account for the climate change observed during
the Maunder minimum

• During the Little Ice Age
• Glaciers in Switzerland advanced crushing
  villages
• The Thames River and Canals in The Netherlands
  often froze
• New York Harbor froze allowing people to walk
  from Manhattan to Staten Island

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2. S. Bjorck of Lund University looked at tree
rings and ice drillings in Greenland and found
that there was a 200-year cold spell 10.300 years
ago. This coincided with a large increase in the
amount of 10Be in the Greenland ice sheet. 10Be
is produced via cosmic rays colliding with
nitrogen and oxygen in the atmosphere. During
high levels of solar activity the Earth's
magnetic field is stronger so less cosmic rays
can penetrate.
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• Abnormally high solar activity during 11001250
  coincided with a period of warming in Europe.
  During this time
• Viking settled in Northern Europe, traveling to
  Greenland and America over seas usually filled
  with dangerous ice
• Grapevines grew as far north as England
• Higher tree lines in the Alps

The Modern Maximum is comparable to the Medieval
Maxium in strength
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Temperatures seem to be correlated with sunspot
maximum
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Wilson claimed in 1997 that the level of solar
activity is increasing from one cycle to the next
and that this can account for 0.71.4 deg warming
over the next 100 years.
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Higher levels of solar activity increases the
amount of ozone in the upper atmosphere.
Schindell argued that this warms the upper
atmosphere and the warm air affects winds from
the stratosphere to the surface.
Postmentier, Soon, and Baliunas have claimed that
there is a correlation with the size of coronal
holes and the Earth's temperature. Large coronal
holes allow more charged particles to strick the
Earth. Presumably these affect the properties of
clouds.
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Coronal Holes are open field lines on the Sun
where the X-ray emission is less
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It is clear that solar activity has some
influence on climate. Since 1950 the sun has
been in an enhanced maximum similar to the Grand
Maximum that caused the Medieval Warm Period in
the 9th to 13th centuries. So, can solar activity
account for the observed global warming? Keep
in mind that carbon dioxide in the atmosphere has
increased by more than 25 in the last century.
Is it the sun or is it humans?
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To answer this Solanki Krivova at MPS did a
study.

• The created a model which reconstructs the solar
  irradiance. This is a four component model which
  including quiet sun, umbra, penumbra, and faculae
• Assumed that all terrestrial temperature changes
  prior to 1970 were due entirely to the sun

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Krivova Solanki reconstruction of Solar
irradiance
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Global Temperatures
Measured irradiance
Reconstructed curve

• Conclusion
• Less than 30 of the Earths temperature rise
  can be attributed to the sun
• A large part of the global warming may be due to
  CO2

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There have been many attempts to try to correlate
solar activity with other things. Some might not
be too crazy
Solar activity might incluence climate so you can
argue there should be a correlation
Others are total rubbish
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Like the claim that solar activity influences
world events
There has been claims that Solar activity
(maxima) has caused political and economic
crises. The End of the Century was written by
Francois Masson in 1979-1980. A publisher was
never found (for good reason) but it was
transcribed into English and published on the
internet
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Dates of Maximum Solar Activity corresponding to
revolts, famine, depressions and other
catastrophes. Below are the events chronicled by
Masson with additions by me in boldface
1702 Protestant Revolts in France, general wars
in Europe
1715 Scottish rebellion, depression and famine
in Europe. Death of Louis XIV and big political
changes 1725 Revolt in Scotland, Peter the Great
dies. Russia enters 50 years of strife 1738
Workers revolt in England. Wesley founds the
first Methodist Society 1729 Tax Revolt in
England
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1760 Founding of Freemasonry. Condemnation of
the Encyclopedists in France. 1776-77
Declaration of Independence, American War of
Independence 1787-88 True beginning of the
French Revolution. Rioting in Paris. Economic
Crisis in French State. 1803 French economic
crisis. Napoleon renews wars with
England 1814-15 Liberal rebellions in France and
other European countries. Uprising in France in
favor of Napoleon on his return from Elba.
Waterloo. 1827 Serious depression in
Europe 1836 Riots in France. TEXANS DEFEATED AT
ALAMO. TEXANS GAIN INDEPENDENCE AT BATTLE OF SAN
JACINTO 1848 Revolution and depression in
Europe 1860-61 Revolutions in Italy, South
Carolina secedes, Civil War begins in USA.
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1870-71 Franco Prussian War 1882 Major
Depression 1892-93 European Tariff war. Stock
Market crash in U.S. 1905-06 Russo-Japanese War.
Imporant revolts in Russia. Einstein 1917-18
Revolution and total change in Russia. Rebellion
in French and Italian armies. Mutiny of the
German fleet. Sun Yat-Sens revolution in
China. 1928-29 Great Depression begins. Peasant
revolts in Russia against collectization of land.
Famin, bloody purges. Revolts in Serbia,
Yugoslavia 1936-37 Francos rebellion in Spain,
civil war. General strikes in France. Start of
ideological wars Fascism vs. Communism 1947-48
Revolts in Eastern satellite nations, revolts in
Indo-China, revolt of Chinese communists against
Chiang Kai-Shek. 1957-58 First uprising of
French colonists in Algeria, Castros revolt in
Cuba. A. HATZES BORN SPUTNIK LAUNCHED. TV
DINNERS INTRODUCED
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1968-69 World youth revolt. The Prague Spring.
Height of Vietnam war. Gold crisis. MAN LANDS ON
MOON BEATLES RELEASE LAST ALBUM FOLLOWED BY
BREAKUP 1979-80? New economic crisis. Numerous
localized wars. First sign of new religion in
USSR. REAGAN ELECTED PRESIDENT HATZES STARTS
GRADUATE SCHOOL JOHN LENNON ASSASINATED. 1990-91
End of USSR. Berlin wall falls (1989) 2000-2001
HATZES BECOMES DIRECTOR OF TLS BUSH GETS
ELECTED. TERRORISTS ATTACKS ON U.S. GEORGE
HARRISON DIES.

• Conclusions. Solar Activity has been
• bad for The Beatles
• good for A. Hatzes
• Mostly affects events in France and England

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1865 Lincoln assassinated 1914 Assassination of
Archduke Ferdinand. Start of WWI 1939-40 Start
of WWII 1963 Kennedy assassinated 1986
Challenger shuttle disaster 2003 Iraq war
starts, Columbia shuttle disaster 2004 Bush
gets re-elected. Madrid train bombings 2005
London terrorist bombings 2007 G8 Protests

• Lessons
• With so many historical events one can always
  find correlations between these and solar maxima
  or minima
• Dont believe everything you read on the
  internet.

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II. The Solar Wind
Spacecraft moving outside of the Earths magnetic
field have demonstrated that a continuous flux of
charged particles streams outwards from the sun
Composition 95 (by number) protons and
electrons, the rest are a particles
Density 320 particles cm3 (mean 10) Plasma
Temperature (velocity dispersion) 100.000
150.000 K. a particles 45 times
higher Velocity 350 750 km/sec. Speed varies
little between 1 20 AU Magnetic field strength
2 10 g (g 105 Gauss)
In 1958 Eugene Parker worked out the model for a
continuously expanding corona
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The radial outflow of the solar wind would follow
the magnetic field lines radially, except that
the sun rotates. Streamlines are given by
1
dr
Vr
Vr


df
r
Vf
wr
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The solar radial component of the magnetic field
switches polarity several times

-
-

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Note Solar Sails do not use the Solar Wind!
Solar Sails use radiation pressure! The solar
wind is very tenuous and does not exert much
force on anything it hits. The solar wind has
1.000 10.000 less force that the radiation
pressure of sunlight
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III. The Solar Wind Earth Interaction
Magnetosphere The Earth has a weak dipole field
that is inclined by 11o from the spin axis.
Forcing by the solar wind modifies this field
creating a cavity called the magnetosphere.
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Inner magnetosphere extends from the nose to a
distance of 8 RE on the night side. It does not
include the poles. This is a stable region
populated by the inner and outer radiation belt.
Typical densities of ions is 1 per cubic cm. In
outer radiation belt the energy of an ion is
about 50 keV. The electrical current associated
with the plasma is the ring current circling the
Earth.
Plasma Sheet Thick layer of hot plasma centered
on the tail's equator. Typical thickness is 37
RE, density 0.30.5 ions per cubic cm and an ion
energy of 25 keV. Electrical currents flows
across the plasma sheet and then closes along the
magnetosphere boundary. In a substorm this
current is diverted earthwards along the magnetic
field lines.
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Tail Lobes Regions of relatively smooth magnetic
fields north and south of the plasma sheet. The
region is a good vacuum with a density of 0.01
ion/cubic cm. It has strong magnetic fields and
thus stores appreciable magnetic energy.
Ionosphere Region 70500 km above the Earth
containing free electrons and ions.
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Motion of a Charged Particle in the Earths
Magnetic Field
Cyclotron Motion

qv x B
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Motion of a Charged Particle in the Earths
Magnetic Field
Differentiate the equation for x

vx

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Motion of a Charged Particle in the Earths
Magnetic Field
Lamor Radius
vx v- eiwct
v- is the velocity of the particle perpendicular
to the magnetic field
vy v- eiwct
dvx
iv- eiwct
vy


dt
Integrating
And the same for x
v-
x x0
i
eiwct
wc
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Motion of a Charged Particle in the Earths
Magnetic Field
Defining the Lamor Radius
v-
mv- c
rL

wc
q BG
x x0
rL sin wct
y y0
rL sin wct
Where is due to the sign of the charge
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Motion of a Charged Particle in the Earths
Magnetic Field
Bz
Charge particles cannot move across the field
lines, but are free to move along the magnetic
field lines
One charge
RL
Opposite charge
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The Ring Current
Gradients in the magnetic field causes a drift
in the guiding center defined by the Lamor
radius. This is because in regions of stronger
magnetic field the Lamor radius is smaller. The
guiding center drift velocity is given by
1
vDB

v- rL
2
At the Earths magnetic equator this causes one
charge to drift eastward, the other westward
creating a ring current.
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Reflection at the Poles
The magnetic moment of a gyrating particle is an
invariant
As a particle moves from weaker to stronger
fields its v- increases.To keep the energy
constant the motion parallel to the field must
decrease. Eventually it comes to stop and gets
reflected. The force causing this reflection is
that on a diamagnetic particle
F m
B
D

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Motions of particles in the Earths magnetic field
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Geomagnetic Storms
The term geomagnetic storm (world-wide
disturbance) was coined by Alexander von
Humboldt. Humboldt convinced the Czar to set up a
network of magnetic observations across Russian
lands. Other sites in throughout the world
established that the magnetic storms were the
same all over the world. There is a steep
increase in the field (50-300 nanotesla) out of a
total intensity of 30-60.000 nT occurring over
12-24 hours, followed by a recovery lasting 1 4
days.
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Magnetic storms are caused when high energy
particles from solar flares collide with the
particles in the ionosphere changing the level of
ionization. These events are associated with

• increased Aurora activity
• fluctuations in compass needle
• disruption of short wave radio communications
• induced currents that blow fuses, damage power
  lines
• disruption of communications
• decay of satellite orbits

In other words, solar flares can cause
significant damage and cost a lot of money to
humans.
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Aurora
Aurorae occur when the charged solar particles
from the solar wind interact with the Earth's
magnetic field. These particles can only spiral
along the field lines and thus strike the polar
regions in what is called the ring of fire.
In times of solar flares this ring of fire
expands and extends to much lower latitudes.
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The Aurora taken from Tautenburg by Christian
Högner
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The colors of the aurora result when charged
particles strike molecules in the upper
atmosphere causing collisional excitation of
emission lines. Most are due to oxygen and
nitrogen O2 emission occurs at 200 km
this is due to the 6300 Å, and 6364 Å lines
(Red) O2 emission occurs at 100 km and
is due to the 5557 Å line (yellow green).
N2 causes the blue colors due to the emission
line at 4652 Å N2 also causes some red
colors
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• Important historical events in the studies of
  Aurora
• 500 BC Hippocrates suggest it is reflected
  sunlight
• 1600 Gilbert discovers that the Earth is a
  magnet.
• 1620 Galileo terms expression Aurora Borealis.
• 1774 Dortous de Mairan relates auroral displays
  to solar activity.
• 1790 Cavendish measures height at 80-110 km.

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• Important historical events in the studies of
  Aurora
• .
• Alexander von Humboldt notes auroral displays
  coincide with magnetic storms.
• 1817 Biot proves aurora is self luminous.
• 1868 Angstrom uses a prism to show that the
  aurora is different from sunlight. Finds auroral
  green line.
• Störmer used triangulation to confirm a height
  of at least 100km for displays
• 1912-23 Oxygen and nitrogen lines identified
• 1939 Hydrogen lines discovered.

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Auroral displays exhibit kinks, curls, and
spirals. These are due to the magnetic field
produced by the moving charged particles
interacting with the Earth's field.
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The Geocorona The outermost part of the
Earth's atmosphere consists of a huge cloud of
hydrogen gas extending a distance of 4-5 Earth
radii. Collisions with this cloud removes the ion
particles added during a geomagnetic storm.
Picture of the geocorona taken by the Apollo
astronauts
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Solar Flare Effect or Magnetic Crochet
A magnetic crochet arises from increased
ionisation in the D and E layers of the
ionosphere caused by the massive increase in
X-ray radiation flux generated by a solar flare.
The ionisation changes the conductivity of the
ionospheric layers causing the electrical
currents to flow more easily. The magnetic field
produced by these currents causes a jump in the
Earth's field. These events are rare
because they are only observed by large flares
that rise to a peak quickly.
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Substorms
These are much more frequent (hours apart) than
magnetic storms. These last about 1 hour during
which energy is rapidly released in the
magnetospheric tail. These are observed
mainly over the polar regions unlike the larger
magnetic storms which are observed globally. They
do not inject as many particles into the ring
current. The first sign of a substorm is
that increase in polar auroras in the midnight
zone. In space synchronous orbit
satellites in the midnight zone see the magnetic
field drop by half and they detect the arrival of
many ions in the 550 keV range.
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Energy of the substorms

• Substorms are believed to be due to a form of
  magnetic reconnection in the magnetospheric tail
• The cusp of the magnetosphere, where the field
  lines part between those pulled to the equator
  and those pulled to the tail, moves closer to the
  equator. Fewer field lines go sunward and more
  into the tail.
• The shift in the cusp weakens the Earth's
  magnetic field near the
• noon side
• More energy is drawn to the tail and the tail
  lobes of the
• magnetosphere expand.
• The stretched'' magnetic field lines in the
  tail reconnect causing the tail to rebound''
  like a slingshot.
• A plasma bubble known as a plasmoid'' moves
  down the tail.

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A Magnetic Plasmoid
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Source of the substorms

• In 1904 Maunder proposed that substorms tended
  to occur in intervals of 27 days. Searches for
  features on the sun that could have been
  responsible for such storms yielded only bland
  and featureless regions, so called M- regions
• In 1962 Mariner 2 on its way to Venus
  established that the solar
• wind contained recurrent fast streams whose
  sources rotated with the sun. The arrival of such
  streams triggered moderate substorms.
• When X-ray observations of the sun began
  (starting with
• Skylab) it was established that the the elusive
  M- regions coincided with coronal holes.
  Coronal holes are regions
• where the magnetic field lines of the sun are
  open, not closed, allowing the particles
  comprising the solar wind to escape along the
  field lines.

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IV. Space Weather
Example
Solar wind 300.6 km/s, density 3 protons per
cubic cm X-ray flares One C2 class and one M2
class X-class big, large radio
blackouts and radiation storms M-class
medium, brief radio blackouts C-class
small few noticeable affects Active Regions
Region 9802 harbors energy for a class X-flare.
There is a 10 chance of a class X flare, and a
50 chance for class M-flare in the next 24
hours. Sunspot 9821 is rapidly growing
and poses a threat for Earth-directed flares
(12.2.2002)
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Interplanetary magnetic field 6.0 nT Coronal
Holes A substantial coronal hole is crossing the
Earth-facing side. Expect strong gusts in the
Solar wind. 11.2.2002 Solar wind gusts buffeted
the Earth's magnetosphere last week. The
encounter triggered mild geomagnetic storms and
Nothern Lights. Geomagnetic storms. Measured via
a K index. Ranges from 0--9 (minor storm has
K5, Severe storm has K gt 6). The probability for
a severe storm is 0.01
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• The study of space weather and the sun are
  important because
• Induced currents from large geostorms can cause
  massive blackouts (1989 Quebec)
• March 24, 1940 Storm disrupted power service in
  New England, New York, Pennsylvania, Minnesota,
  Quebec, and Ontario
• Feb 9-10, 1958 Power transformer failed in
  British, Columbia
• Aug, 1972 Reclamation power station experienced
  swings of power line voltages of 25.000 volts. A
  230.000 volt transformer exploded. Manitoba Hydro
  recorded power drops of 164 44 megawatts in
  minutes.
• 1989 9 hour power blackout in Quebec
• Costs 100 Million damage to power transformer
  of Minnesota Power and Electric. Estimated cost
  of a storm slightly more severe than the 1989
  storm 9 Billion!

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• Radiation dosages lethal to astronauts
• Magnetic storms can interfere with GPS,
  compasses
• Currents in pipelines enhance the rate of
  corrosion
• In June 1989 a powerful pipline explosion
  demolished
• part of the Trans-Siberian Railroad engulfing two
  trains. 800 people
• died. Alaskan pipeline has safeguards against
  geomagnetic storms.

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• Magnetic storms can damage satellites
• 1982 GOES-4 Weather satellite has radiometer
  disabled for 45 min.
• 1989 GOES-7 loses half its solar cells to proton
  release from flare.
• Two Canadian satellites disabled due to activity
• 1997 Telstar 401 experienced massive power
  failure

Shorten the lifetime of low orbit satellites
(e.g. Hubble Telescope) Bad news Predictive
abilities poor, only up to 1 hour in advance can
we geta reliable prediction. Good news
It takes particles 2-4 days to get here.