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

Atmosphere Layers

The Thermosphere

Atmospheric Distribution under Hydrostatic EquilibriumPressure gradient:For perfect gas approximation:Combining the above 2 equations yields:is the scale heightz is altitudeg(z) is the acceleration of gravityr is mass densityk = Boltzmanns constantM = mean mass of the moleculesIf H does not vary with altitude z:

Atmospheric Density DistributionIf T, M, and g are not functions of z:Each species has its own scale height.

Column DensityColumn Density: the number of molecules per unit area in a column above z0:

Ionospheric Regions

Ionospheric RegionsSolar Min and Max Distributions

Ionospheric RegionsDay and Night Distributions

Sources of IonizationCourtesy of Scot Elkington

Altitude Attenuation of Solar IrradianceThermosphereMesosphereTroposphereStratosphere

Ionization Rate (cm-3 sec-1)Solar MinimumSolar MaximumCourtesy of Stan Solomon

Principal Chemical Processes in the Thermosphere and IonospherePhotoionization:hu + O [ O+ + e-hu + O2 [ O2+ + e-hu + N2 [ N2+ + e-Collisional Ionization:e- + O [ O+ + 2e- Dissociative Recombination:O2+ + e- [ O + ON2+ + e- [ N + NNO+ + e- [ N + OCharge Exchange:H + O+ [ H+ + OO2 + O+ [ O2+ + ON2 + O+ [ N2+ + ORadiative Recombination:O+ + e- [ hu + ORecombination:O + O + N2 [ O2 + N2Conversion:N2+ + O [ NO+ + ON2 + O+ [ NO+ + O

Thermospheric Compositions

Ionospheric Compositions

Electrodynamic ProcessesIn the Ionospere

Ionospheric Currentswhere SP = height integrated Pedersen conductivity SH = height integrated Hall conductivity

Horizontal Current:JPJHIonospheric Currents

Distributions of Ionospheric Currents

Energy Transfer to the IonospherePoyntings Theorem: where

Horizontal Current:Energy Transfer to the Ionosphere(Ohms Law)

Comparison of Energy Inputs From the Sun to the Earth

Solar and Magnetospheric Energy BudgetSolar irradiance: 1017 W (with 0.1% variability)Solar wind kinetic power: 1013~1014 W Magnetospheric power: 1011~1013 WAuroral precipitation: 109~1011 WJoule heating rate: 1010~1012 WRing current injection: 1010~1012 WPlasma sheet heating: ~1011 WPlasmoid ejections: 1010~1011 W Energy input to the magnetosphere: 1016~1018 Joules Energy released by a typical CME: 1024 Joules Mass input into the magnetosphere: 105~106 kg Mass released by typical CME: 2~5x1012 kgPower consumed by US: ~8x1011 W

Solar Flare Effects on the thermosphere and Ionosphere

Electron Density at ~110 km During Flare on 9/7/20051720UT1730UT1740UT1750UT1800UT1810UT1820UT1830UT1840UT1850UT1900UT1910UT1x1033x1051x1033x1051x1033x105cm-3cm-3cm-3Flare onset

Neutral Temperature Change at ~350 km During Flare1720UT1730UT1740UT1750UT1800UT1810UT1820UT1830UT1850UT1910UT2000UT2200UT0100oK0100 oK0100oKFlare onset

Solar Energetic Proton Effects on the Upper Atmosphere

% Change of Electron Density due to SEPsOctober 27 November 5, 2003October 27 November 5, 2003Northern Polar CapSouthern Polar Cap

Changes of NOX (NO+NO2) and Ozone due to SEPsOctober 27 December 31, 2003October 27 December 31, 2003O3NOXO3NOXNorthern Polar CapSouthern Polar Cap

Effects of Magnetospheric Energy Inpouton the Upper Atmosphere

TIEGCM Difference TEC Maps During Storm1600UT1700UT1730UT1800UT1830UT1900UT1930UT2000UT2030UT2100UT2130UT2230UT80-880-880-8

TIEGCM Difference O/N2 Ratio During Storm1600UT1700UT1730UT1800UT1830UT1900UT1930UT2000UT2030UT2100UT2130UT2230UT0.50-0.50.50-0.50.50-0.5

Neutral Temperature Change at ~350 km During Storm1610UT1620UT1630UT1640UT1710UT1730UT1750UT1820UT1900UT1940UT2100UT2130UT0300 Kelven0300 Kelven0300 Kelven

Neutral Temperature Change at ~350kmDuring Flare on Sep. 70100DTN OKDuring Storm on Sep. 100300DTN OK

Homework Assignment

Homework Problem 1:Name the layers 1 to 4Identify the curves A, B, C and D

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.

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 )

Dipole Magnetic Field

Magnetic Reconnection & Circulation

Magnetospheric Topology & Plasma ConvectionBow ShockMagnetopauseNoon-Midnight Meridional Plane

There are generally 2 ways that the Sun tranmits its energies to the Earth: through the radiation of lights at various wavelengths, and through the solar wind interacting with the Earths magnetosphere.Geomagnetic storms are a way that the magnetosphere releases the excessive energies originated from the Sun. Here is ballpark estimate of the different solar and magnetospheric energy inputs:solar radiation is by far the most important form of solar energy output, but with .1% variation over a solar cycle comparison to the power consumed by entire USSPE of MeV energies dissipate below 100 km. These plots show the % change of Ne over Eureka in northern Canada, and over the Antarctic between Oct 27 Nov 5. The peak height of Ne enhancement is around 65 km, compared to the 85km peak height due to ring current electronsWhile the response in electron density to SEPs is somewhat spontaneous, the effects of SPE on the neutral atmosphere is long lasting.the period plotted here is from Oct 27 until the end of the year. During SPE, NO is a result of N2 and O2 dissociation NOx and HOx cause catalytic Ozone destruction Once generate, the Ozone depletion lasts for many monthsThis is noon-midnight meridional cut of the magnetosphere. The out boundary is called magntopause, which separates the geomagnetic field & terretially originated plasmas from the solar widn & IMF domain. Since the Earth acts as an obstacle to the super-sonic SW flows, a bow shock forms at the upper stream of the magnetosphere. Cross the bow shock, SW becomes subsonic. The red lines mark the last closed field lines.In the equatorial plane, the open-closed mangetic field boundary forms an enclosed area marked by the red line. Inside, the flow is sunward, and outside the flow is sunward.Mapping down to the low-latittude ionosphere, because the magnetic field line converges, the outside region maps to the polar cap where the plasma convection is anti-sunward. Note that Noon is on the left. The closed field region maps to lower latitudes where the convection is sunward. Since the plasmas are ExB drift, these flow lines are also equipotentials. For this idealized situation, the OCB coinsides with CRB.