Earth

1
Earths Atmospherewith focus on the upper
atmosphere above 100km(Thermosphere and
Ionosphere)
Gang LuHigh Latitude ObservatoryNational Center
for Atmospheric Research
2007 Summer School for REU
2
Outline

• Atmospheric Layers
• The Thermosphere Ionosphere
• Electrodynamical Processes in the Ionosphere
• Storm Impacts on the Upper Atmosphere
• Homework Problems

3
Atmosphere Layers
4
The Thermosphere
5
Atmospheric Distribution under Hydrostatic
Equilibrium
z is altitude g(z) is the acceleration of
gravity r is mass density
Pressure gradient
For perfect gas approximation
k Boltzmanns constant M mean mass of the
molecules
Combining the above 2 equations yields
is the scale height
If H does not vary with altitude z
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Atmospheric Density Distribution
If T, M, and g are not functions of z
Each species has its own scale height.
7
Column Density
Column Density the number of molecules per unit
area in a column above z0
8
Ionospheric Regions
9
Ionospheric Regions Solar Min and Max
Distributions
10
Ionospheric Regions Day and Night Distributions
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Sources of Ionization
Courtesy of Scot Elkington
12
Altitude Attenuation of Solar Irradiance
Thermosphere
Mesosphere
Stratosphere
Troposphere
13
Ionization Rate (cm-3 sec-1)
Solar Minimum
Solar Maximum
Courtesy of Stan Solomon
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Principal Chemical Processes in the Thermosphere
and Ionosphere
Conversion N2 O NO O N2 O NO O
Photoionization hu O O e- hu O2 O2
e- hu N2 N2 e-
Recombination O O N2 O2 N2
Collisional Ionization e- O O 2e-
Dissociative Recombination O2 e- O O N2
e- N N NO e- N O
Charge Exchange H O H O O2 O O2
O N2 O N2 O
Radiative Recombination O e- hu O
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Thermospheric Compositions
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Ionospheric Compositions
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Electrodynamic Processes In the Ionospere
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Ionospheric Currents
where SP height integrated
Pedersen conductivity SH height
integrated Hall conductivity
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Ionospheric Currents
Horizontal Current
JH
JP
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Distributions of Ionospheric Currents
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Energy Transfer to the Ionosphere
Poyntings Theorem
where
22
Energy Transfer to the Ionosphere
Horizontal Current
(Ohms Law)
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Comparison of Energy Inputs From the Sun to the
Earth
Source Energy Input (W/m2) Deposition Altitude (km)
Solar Radiation Total irradiance UV 200-300nm UV 120-200nm EUV 1368 16 0.1 0.003 Surface 0-50 km 50-120 km 100-500 km
Particles Solar Energetic Protons Magnetosph. Protons Magnetosph. Electrons Galactic Cosmic Rays 0.002 0.001-0.006 0.003-0.03 0.000007 30-90 km 100-130 km 70-130 km 0-90 km
Joule Heating E 1100 mV/m 0.0000140.14 100-500 km
Solar wind Kinetic 1/2rv3 Electromagnetic ExB/m0 0.0003 0.00003
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Solar and Magnetospheric Energy Budget

• Solar irradiance 1017 W (with 0.1 variability)
• Solar wind kinetic power 10131014 W
• Magnetospheric power 10111013 W
• Auroral precipitation 1091011 W
• Joule heating rate 10101012 W
• Ring current injection 10101012 W
• Plasma sheet heating 1011 W
• Plasmoid ejections 10101011 W

Power consumed by US 8x1011 W

• Energy input to the magnetosphere 10161018
  Joules
• Energy released by a typical CME 1024 Joules
• Mass input into the magnetosphere 105106 kg
• Mass released by typical CME 25x1012 kg

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Solar Flare Effects on the thermosphere and
Ionosphere
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Electron Density at 110 km During Flare on
9/7/2005
1720UT
1730UT
1740UT
1750UT
Flare onset
3x105
cm-3
1x103
1800UT
1810UT
1820UT
1830UT
3x105
cm-3
1x103
1840UT
1850UT
1900UT
1910UT
3x105
cm-3
1x103
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Neutral Temperature Change at 350 km During Flare
1720UT
1730UT
1740UT
1750UT
Flare onset
100
oK
0
1800UT
1810UT
1820UT
1830UT
100
oK
0
1850UT
1910UT
2000UT
2200UT
100
oK
0
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Solar Energetic Proton Effects on the Upper
Atmosphere
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Change of Electron Density due to SEPs
Southern Polar Cap
Northern Polar Cap
October 27 November 5, 2003
October 27 November 5, 2003
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Changes of NOX (NONO2) and Ozone due to SEPs
Northern Polar Cap
Southern Polar Cap
NOX
NOX
O3
O3
October 27 December 31, 2003
October 27 December 31, 2003
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Effects of Magnetospheric Energy Inpout on the
Upper Atmosphere
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TIEGCM Difference TEC Maps During Storm
1700UT
1730UT
1800UT
1600UT
8
0
-8
1830UT
1900UT
1930UT
2000UT
8
0
-8
2030UT
2100UT
2130UT
2230UT
8
0
-8
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TIEGCM Difference O/N2 Ratio During Storm
1700UT
1730UT
1800UT
0.5
1600UT
0
-0.5
1830UT
1900UT
1930UT
2000UT
0.5
0
-0.5
2030UT
2100UT
2130UT
2230UT
0.5
0
-0.5
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Neutral Temperature Change at 350 km During Storm
1610UT
1620UT
1630UT
1640UT
300
Kelven
0
1710UT
1730UT
1750UT
1820UT
300
Kelven
0
1900UT
1940UT
2100UT
2130UT
300
Kelven
0
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Neutral Temperature Change at 350km
During Flare on Sep. 7
During Storm on Sep. 10
100
300
DTN OK
DTN OK
0
0
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Homework Assignment
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• Homework Problem 1
• Name the layers 1 to 4
• Identify the curves A, B, C and D

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Homework Problem 2 If the neutral temperature at
300 km is increases from 1300 oK to 1500 oK
during a solar flare event, will the neutral
number density at 300 km increase or decrease?
Assuming the thermosphere is mainly composed of
atomic oxygen.
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Homework Problem 3 When neutral wind is
neglected, Joule heating QJH is simply expressed
as Rewrite the full expression for Joule
heating in the reference frame of neutral wind
. Do neutral winds contribute positively or
negatively to Joule heating? (Hint replacing
with , where )
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Dipole Magnetic Field
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Magnetic Reconnection Circulation
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Noon-Midnight Meridional Plane
Magnetospheric Topology Plasma Convection
Magnetopause
Bow Shock