The coupling of the Solar-terrestrial
systems
Unit Outline
• Earth’s internal structure, atmospheric structure, and magnetosphere
• Solar General Structure
• Solar activity at or above the photosphere
• Space Weather
Earth structure
The Atmosphere
Geo-magnetism
Sources for any natural magnet
• Imbalanced atomic dipole moments
result in orientation of field lines and
bulk magnetic properties of some
elements and compounds.
• Geomagnetism a form of
ferromagnetism resulting from the
atomic properties of the iron, cobalt,
and nickel that make up the internal
portions of the earth as well as the
coupling forces of the crystal lattices
in the solid state which serve to align
the atomic dipoles and generate bulk
magnetic fields.
• Further reading on magnetism
http://www.rare-earth-magnets.com/t-magnetism.aspx
Complex Fields that are ever changing
Images on wikipedia common media license
Solar Structure
General Structure
Radius
690,000 km
Average
Density
1410 kg/m3
Surface Temp
5780 K
Luminosity
3.86 x 1026 W
• The sun contains no solid matter
• Light we ‘see’ is from
photosphere (very thin, 500 km
thick)
• This gives the sun the
appearance of having a
sharp edge to it.
General Structure
Interior Model
• Assume Hydrostatic
Equilibrium
• Outward pressure of
hot gas balances the
inward pull of gravity
Outward force = inward force
General Structure
Patterns of Density
and Temperature
Both decrease with
distance from the
core
General Structure
Evidences of internal structure
Spectral lines of
certain elements are
doppler shifted
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General Structure
Evidence of internal structure
Surface of the sun oscillates or vibrates with certain frequency
• Surface patterns result from internal pressure waves that reflect off of the
photosphere
• Propagation of these pressure waves through the interior allows scientists to model
the density and temperature profiles as well as internal movement of material.
Images on wikipedia common media license
General Structure
Evidence cont.
• From the photospheric expression of moving
(doppler shifted) gas, we can map out the
internal structure
• Models match observations quite well
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Active features of the
photosphere
Sunspots appear
dark because slightly
cooler than
surroundings.
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Active features of the
9.4
The Active Sun
photosphere
Sunspots come and go,
typically in a few days.
Sunspots are
linked by
pairs of
magnetic
field lines.
http://www.windows2universe.org/sun/sun_polar_regions.html
9.4 The Active Sun
The Active Features of the Photosphere
The Sun has an 11-year sunspot cycle, during which
sunspot numbers rise, fall, and then rise again.
9.4Active
The Active
Sun of the Photosphere
The
Features
This is really a 22-year cycle, because the spots switch
polarities between the northern and southern
hemispheres every 11 years.
Maunder minimum: few, if any, sunspots.
Images on wikipedia common media license
The Active Features of the Photosphere
Areas around sunspots are active; large eruptions
may occur in photosphere.
Solar prominence is large sheet of ejected gas.
http://soho.nascom.nasa.gov/gallery
/
Active features of the
9.4
The Active Sun
photosphere
The rotation of the Sun drags magnetic field lines
around with it, causing kinks. A Prominence can be
seen when a loop is near the edge.
A Solar flare is a large
explosion on Sun’s
surface, emitting a
similar amount of
energy to a
prominence, but in
seconds or minutes
rather than days or
weeks.
http://soho.nascom.nasa.gov/gallery
/
A coronal mass ejection
emits charged particles
that can affect the Earth.
http://soho.nascom.nasa.gov/gallery
/
9.4 The Active Sun
Solar wind escapes Sun mostly through coronal holes,
which can be seen in X-ray images.
http://soho.nascom.nasa.gov/gallery
/
9.4 The Active Sun
Solar corona changes
along with sunspot
cycle; is much larger
and more irregular at
sunspot peak.
Solar wind – a fast moving flux of radiation and
charged particles interacting with earth’s magnetic
field.
"Parts of the Sun." SOHO-Gallery. Web. 01 Aug. 2014. http://soho.nascom.nasa.gov/gallery/
Solar inputs and Earth’s Outputs
http://earthobservatory.nasa.gov/Features/EnergyBalance/page4.php
The paths of energy through the
atmosphere
Images on wikipedia common media license
Space Weather
Detection of a Solar Flare
-
Solar Flare events happen in stages
-
The first stage, or the precursor stage, the
build-up of magnetic energy triggers the
event and can be seen via soft x-rays
-
The second stage, impulsive stage is where
the massive amount of energy is released
across almost all spectra
-
Especially the Radio Spectrum!!!
Space Weather
The Ionosphere As a boundary between the
solar wind magnetosphere
and atmosphere, it can be a
sensor for the influence of
space weather on the
atmosphere
Space Weather
Interactions of solar wind and earths
magnetosphere
Space Weather
Coronal Mass Ejections (CMEs)
-
Often associated with solar flares
-
Extremely large ejections of solar wind and energy
-
Has a larger push on Earth’s magnetosphere than normal
causing more extreme disturbances in our upper
atmosphere
-
http://en.wikipedia.org/wiki/File:Solar_Storm_on_Augus
t_1,_2010.OGG
-
http://en.wikipedia.org/wiki/File:Closeup_on_launching_filament_%28SDOAIA,_304_%C3%85%29.ogv
-
http://en.wikipedia.org/wiki/File:A_Coronal_Mass_Ejecti
on_strikes_the_Earth.ogv
Space Weather
Case Study: The 2003 Halloween
Storm
This solar CME caused a
massive geomagnetic storm
that resulted in power
outages in northern Europe.
"Parts of the Sun." SOHO-Gallery. Web. 01 Aug. 2014. http://soho.nascom.nasa.gov/gallery
Space Weather
Aurora Borealis (The Northern Lights)
Images on wikipedia common media license
Space Weather
The Halloween storm of 2003 created
many disturbances in the atmosphere
were studied for years afterward
Studying the Ionosphere with Radio
waves
Two methods:
Ionosonde
Use radar from the ground or from
satellite.
•
A huge pulse of radio waves
(Megawatts) is reflected off of
ionosphere
•
Return signal contains
information about the
structure, temperature, and ion
content of the ionosphere.
Image from: http://www.amateur-radio-wiki.net/index.php?title=File:Ionosonde.jpg
Studying the ionosphere with Radio
Use current GPS/GNSS system
•
For GPS navigation our
receivers are constantly
sending radio signals back
and forth from the
satellites.
•
The ionosphere interferes
with these signals and the
level of interference can be
used by scientists to
estimate properties of the
ionosphere.
A. Coster 2013 MIT Haystack
Summary
Geospace environment includes solar
inputs of radiation and high energy
particles
Variations in the solar wind from events
like CMEs, flares, promenances,
faculae,…. May cause geomagnetic
disturbances or storms
Monitoring the ionosphere is important
for understanding the effect of solar
variability on earths environment for
engineering purposes as well as climate
change.
References
• http://www.rare-earth-magnets.com/t-magnetism.aspx
• Free GNU license agreement http://www.gnu.org/copyleft/fdl.html
• "Parts of the Sun." SOHO-Gallery. Web. 01 Aug. 2014.
http://soho.nascom.nasa.gov/gallery/
• http://gnss.be/atmosphere_tutorial.php
• Hathaway, David H. "Sun Spot Cycles." NASA/Marshall Solar Physics.
NASA/Marshall, 4 July 2014. Web. 04 Aug. 2014.
http://solarscience.msfc.nasa.gov/SunspotCycle.shtml
• http://earthobservatory.nasa.gov/Features/EnergyBalance/page4.php
• "Climate and Earth’s Energy Budget : Feature Articles." Climate and
Earth’s Energy Budget : Feature Articles. Web. 08 Aug. 2014.
<http://earthobservatory.nasa.gov/Features/EnergyBalance/page4.php>.
• Shapley, Patricia. "Our Energy Budget." Our Energy Budget. University of
Illinois, 2012. Web. 08 Aug. 2014.
<http://butane.chem.uiuc.edu/pshapley/GenChem2/C1/1.html>.