Thermosphere-Ionosphere

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�� Thermosphere-Ionosphere-Electrodynamics General Circulation Model TIEGCM Maura Hagan Jiuhou Lei, Gang Lu Ray Roble, Art Richmond, Stan Solomon Ben Foster, Astrid Maute, Liying Qian

High Altitude Observatory National Center for Atmospheric Research Boulder, Colorado USA

12 May 2006 ICTP Space Weather School Maura Hagan - 1 - TIEGCM Objectives • Describe the chemistry, dynamics and electrodynamics of the Earth’s upper atmosphere within a mathematical framework • Diagnose the Earth’s upper atmosphere; develop understanding by comparing model results with observations • Predict future conditions of the Earth’s upper atmosphere (e.g., thermospheric cooling associated with increased CO2) • Strategies: – 1-D: column model (global mean) – 2-D: zonal averages (height & latitude) – 3-D: global

12 May 2006 ICTP Space Weather School Maura Hagan - 2 - Historical Development of TIEGCM • TGCM; an adaptation of the NCAR climate model (ca.1970) – 97 to 500 km (solar minimum) – solar EUV heating – thermospheric composition – molecular diffusion – parameterized ionosphere • TIGCM (ca. 1988) – added ionospheric chemistry and dynamics Ray Roble – parameterized electric fields • TIEGCM (ca. 1992) – added self-consistent low and middle latitude electrodynamics – parameterized high-latitude Art Richmond electrodynamics

12 May 2006 ICTP Space Weather School Maura Hagan - 3 - Thermosphere-Ionosphere-Electrodynamics General Circulation Model TIEGCM

Part 1: Model Overview • functional description • references • select formulations and numerical schemes

12 May 2006 ICTP Space Weather School Maura Hagan - 4 - TIEGCM Functional Description • comprehensive, first-principles, three-dimensional, non-linear representation of the coupled thermosphere and ionosphere system, including a self-consistent solution of the middle and low- latitude dynamo field, • solves the 3-D momentum, energy and continuity equations for neutral and ion species at each time step (typically 120–180s), • employs a semi-implicit, fourth-order, centered finite difference scheme on each pressure surface in a staggered vertical grid, • runs in either serial or parallel mode on a variety of platforms, including Linux workstations and supercomputers. The standard low-resolution grid parameters are: • Latitude: -87.5° to 87.5° in 5° increments • Longitude: -180° to 180° in 5° increments • Altitude: 29 pressure levels from -7 to +6.5 in increments of 2 grid points per scale height • Lower boundary: ~97 km • Upper boundary: ~500–700 km depending on solar activity

12 May 2006 ICTP Space Weather School Maura Hagan - 5 - NCAR TIEGCM Development References: Dickinson, R. E., E. C. Ridley and R. G. Roble, A three-dimensional general circulation model of the thermosphere, J. Geophys. Res., 86, 1499-1512, 1981. Dickinson, R. E., E. C. Ridley and R. G. Roble, Thermospheric general circulation with coupled dynamics and composition, J. Atmos. Sci., 41, 205-219, 1984 . Richmond, A. D., E. C. Ridley and R. G. Roble, A Thermosphere/Ionosphere General Circulation Model with coupled electrodynamics, Geophys. Res. Lett., 19, 601-604, 1992. Roble, R. G., and E. C. Ridley, An auroral model for the NCAR thermospheric general circulation model (TGCM), Annales Geophys., 5A, 369-382, 1987. Roble, R. G., E. C. Ridley and R. E. Dickinson, On the global mean structure of the thermosphere, J. Geophys. Res., 92, 8745-8758, 1987. Roble, R. G., E. C. Ridley, A. D. Richmond and R. E. Dickinson, A coupled thermosphere/ionosphere general circulation model, Geophys. Res. Lett., 15, 1325- 1328, 1988. Roble, R. G., and E. C. Ridley, A thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (time-GCM): equinox solar cycle minimum simulations (30- 500 km), Geophys. Res. Lett., 21, 417-420, 1994. Roble, R. G., Energetics of the mesosphere and thermosphere, AGU, Geophysical Monographs, eds. R. M. Johnson and T. L. Killeen, 87, 1-22, 1995.

12 May 2006 ICTP Space Weather School Maura Hagan - 6 - TThheerrmmooddyynnaammiicc eeqquuaattiioonn -- ggeenneerraall ffoorrmm

"T "T (Q # L ) = #($ + )% #U & 'T + tot tot "t "Z C p

diabatic adiabatic heating ! heating & cooling

T temperature heat advection Γ atmospheric stability

Z vertical coordinate ln(Po/P) ω vertical velocity = "Z "t U horizontal velocity vector

Qtot total heating rate Ltot total cooling rate Cp specific heat per unit mass ! ! 12 May 2006 ICTP Space Weather School Maura Hagan - 7 - TTIIEEGGCCMM TThheerrmmooddyynnaammiicc eeqquuaattiioonn

Z * $ '. "T ge " , KT "T 2 g 1 "T , = + + KE H Cp#& + )/ "t PoCp "Z -, H "Z % Cp H "Z (0,

'& T RT * (Q " L) "U # $T "%) + , + &Z C m C ! ( p + p g gravitational acceleration -4 Po reference pressure; 5x10 µbar KT molecular thermal conductivity H scale h!eig ht KE eddy diffusion coefficient = eddy thermal conductivity ρ total mass density m mean molecular mass Q heating rate L total cooling rate

12 May 2006 ICTP Space Weather School Maura Hagan - 8 - ! TTIIEEGGCCMM TThheerrmmooddyynnaammiicc eeqquuaattiioonn

diabatic heating • absorption of solar radiation - UV and EUV • absorption of energetic particles • chemical heating - exothermic reactions • ion - neutral collisions; Joule heating

Schematic absorption diabatic cooling of • airglow UV and EUV…. • CO2 infrared cooling up next • nitric oxide (NO) infrared cooling

12 May 2006 ICTP Space Weather School Maura Hagan - 9 - Solar UV & EUV

photoelectron heating photoionization O2 + hν  O + O N2 + hν  N + N

electron ionosphere major minor and with O+ species species and Τε Σnn with O Σnn species Σnn Ion diffusion: diffusion diffusion T Σn 2 energy n O + N + NO+ i O O and N( D) 2 2 2 4 equation N+ in PCE* N N( S) 2 NO

*photochemical equilibrium

heating heating Ion/neutral neutral O chemistry gas recombination energy equation

heating electron/ion/neutral collisions heating neutral-neutral chemistry

12 May 2006 ICTP Space Weather School Maura Hagan - 10 - CCoonnttiinnuuiittyy EEqquuaattiioonn -- ggeenneerraall ffoorrmm

"#n + $ %(#nU) = CSn &CRn "t transport chemical production & loss

ρn ! mass density of species, n U wind velocity vector

CSn mass source of minor species, n CRn mass sink of minor species, n # " = n mass mixing ratio of species, n, for total mass density, ρ n # "# n +U $ %# = S & R "t n n n ! S source of minor species, n CS " CR n S " R = n n R sink of minor species, n n n n #n 12 May 2006 ICTP Space Weather School Maura Hagan - 11 - ! ! TIEGCM Minor Neutral Species Transport:

"#n $Z " % " ( = $e Dn $ En #n + Sn $ Rn "t "Z &'" Z )*

( '%n + Z ' "Z ( ' 1 'm+ " V # $%n +& + e e KE (Z) + %n )* 'Z ,- 'Z )*' Z m 'Z ,- !

Ψn mass mixing ratio of minor species, n D molecular diffusion coefficient ! n En gravitational, thermal diffusion, and frictional interaction with the major species; $ mn 1 #m' 1 #T &1 " " ) "*n + F+n % m m #Z ( T #Z

mn mass of the minor species, n m average mass of the major species !

12 May 2006 ICTP Space Weather School Maura Hagan - 12 - ! TTIIEEGGCCMM SSoolluuttiioonn -- CCoonnttiinnuuiittyy EEqquuaattiioonnss -- 11 derivatives become finite differences at model grid points – for each specie, i – at every grid point, x grid spacing, Δx – at every time, t time step, Δt Chemistry "# i = S $ R "t i i Sufficiently small time step - explicit: m+1 m t S t , m R t , m "i =!" i + # $[ i ( m "i ) % i ( m "i )] Otherwise - implicit: m+1 m t S t , m+1 R t , m+1 "i = "i + # $[ i ( m+1 "i ) % i ( m+1 "i )] !

! 12 May 2006 ICTP Space Weather School Maura Hagan - 13 - TTIIEEGGCCMM SSoolluuttiioonn -- CCoonnttiinnuuiittyy EEqquuaattiioonnss -- 22 derivatives become finite differences at model grid points – for each specie, i – at every grid point; grid spacing, Δx – at every time step, Δt Eulerian Transport

"#i "Fi + = 0 for flux, Fi = c"i "t "x

leap-frog method: ! m+1 m#1 $t m m ! "i, j = "i, j # %[Fi , j+1 # Fi , j#1 ] $x "t if c #1 (CFL stability condition) "x !

! 12 May 2006 ICTP Space Weather School Maura Hagan - 14 - TTIIEEGGCCMM SSoolluuttiioonn -- CCoonnttiinnuuiittyy EEqquuaattiioonnss -- 33 derivatives become finite differences at model grid points – for each specie, i – at every grid point; grid spacing, Δx – at every time step, Δt Diffusion "# " $ "# ' i = & K i ) for diffusion coefficient, K > 0 "t "x % "x ( explicit: m+1 m ! "i, j # "i, j K m m m "t ! = " # 2" + " stable if 2K 2 #1 $t ($x) 2 ( i , j+1 i , j i, j#1 ) ("x) implicit: m+1 m " # " K m+1 m+1 m#1 i, j i, j = " # 2" + " ! $t ($x) 2 ( i , j+1 i , j i , j+1 ) !

12 May 2006 ICTP Space Weather School Maura Hagan - 15 -

! EEqquuaattiioonnss ooff NNeeuuttrraall MMoottiioonn

( + . 1 " U# " U% " " g " U% " p " U# = $ U# $ U# $& U# $ Z + * 2' + -V % cos# + g 0( µm + µT ) U# 3 $4 ni (U# $V# ) "t r "# rsin# "% "p r "# ) rsin# , "p/ H "p 2

( + . 1 " U% " U# " " g " U# " p " U# = $ U# $ U# $& U# $ Z $* 2' + -U % cos% + g 0( µm + µT ) U# 3 $4 ni (U# $V# ) ! "t r "% rsin% "# "p r "# ) rsin% , "p/ H "p 2 advection pressure Coriolis viscosity ion drag ! gradient 1 "p g # "Z & * "# = # Uz = % ( ) = $% p &U p "Z RT $ "t ' p +g "p r radius of the Earth Ω rotation rate of the Earth ν ion-neutral collision frequency ni ! ! Vk ! k component of ion velocity, V µm molecular viscosity coefficient µT thermal viscosity coefficient

12 May 2006 ICTP Space Weather School Maura Hagan - 16 - TTIIEEGGCCMM IIoonnoosspphheerree ⊗E Continuity Equation electron "[n] = q # l # $ %[n]V ion "t

qe = "qi ne = "ni i i Bb

! V = V || +V " where V ||,V " are the parallel, perpendicular components of V ! For exam!pl e, O+ - 1' 1 * 0 ! V || = .!b " ) g $ &(pi + pe ), + b "U1b / # ( %i + 2 1 Need a global specification of B V " = E # b B in order to solve for E and V ! 12 May 2006 ICTP Space Weather School Maura Hagan - 17 -

! TTIIEEGGCCMM GGeeoommaaggnneettiicc CCoooorrddiinnaatteess

Note the offset between the geographic and geomagnetic poles.

12 May 2006 ICTP Space Weather School Maura Hagan - 18 - TIEGCM Calculations • Upper Boundary - specify - solar flux - aurora - high latitude convection electric field (cross-cap potential drop) • Lower Boundary - specify - tides coming from the lower atmosphere • specify some initial state of the T-I system • on the geographic grid - calculate composition (neutral and ion) - solve the thermal energy equations - solve the neutral equation of motion • on the geomagnetic grid - solve the dynamo equation (low-mid latitudes) - solve the ion and electron equations of motion

12 May 2006 ICTP Space Weather School Maura Hagan - 19 - TIEGCM Ionosphere-Thermosphere Coupling

Why is TEC largest near 0o longitude? Why is TEC comparatively larger in the summer hemisphere?

12 May 2006 ICTP Space Weather School Maura Hagan - 20 - TIEGCM Ionosphere-Thermosphere Coupling The sub-solar point is at 0o longitude at 12UT; in the Southern hemisphere during December.

V|| U U V||

Thermospheric winds blow from “hot” to “cold” (pressure gradient-ion drag balance) ⇒ decreased (increased) Recombination in the Southern (Northern) hemisphere

12 May 2006 ICTP Space Weather School Maura Hagan - 21 - Thermosphere-Ionosphere-Electrodynamics General Circulation Model TIEGCM Part 2: Model Validation • exemplary effort • highlights of a recent study • a set of 1-D assessments • climatologies of Incoherent Scatter Radar (ISR) data • led by Jiuhou Lei • HAO/ASP Postdoctoral Fellow • PhD 2005, Chinese Academy of Sciences

12 May 2006 ICTP Space Weather School Maura Hagan - 22 - GGlloobbaall IInnccoohheerreenntt SSccaatttteerr RRaaddaarr NNeettwwoorrkk

Millstone Hill, Massachusetts, USA

Primary measurements: • electron density, Ne • electron temperature, Te Arecibo, Puerto Rico • ion temperature, Ti • line-of-sight ion velocity, Vi

12 May 2006 ICTP Space Weather School Maura Hagan - 23 - Sample ISR Climatologies

• electron density (Ne) • electron temperature (Te) • ion temperature (Ti) - Millstone Hill: 1976-2002 - Arecibo: 1966-2000 • geomagnetically undisturbed

- Ap < 30 • solar cycle

- minimum: F10.7 < 100 - maximum: F10.7 > 170 • season - equinox: March & April - summer: June & July - winter: December & January

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 24 - TIEGCM Validation Objective: account for ionosphere - plasmasphere coupling 1- Assess Upper Boundary Conditions using ISR data • electron heat flux before: 7 7 Fday= -6 x10 (F10.7A(θ)) - 4.8 x10 (F10.7) A(θ) = 1 for θ > 45o latitude = sinθ for θ < 45o

Fnight = Fday/2 at night • electron heat flux after: 7 7 Fday= -4 x10 (F10.7A(θ)) - 2 x10 (F10.7) A(θ)= 1 for θ > 45o latitude = sinθ for θ < 45o Fnight = Fday/B(θ) at night B(θ) = 5 for θ = 45o = 10 for θ = 0o

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 25 - TIEGCM Validation

2 - Assess Upper Boundary Conditions using ISR data • O+ flux before: 8 -2 -1 Φday = 2 x10 cm s during daytime (out) 8 -2 -1 Φnight -2 x10 cm s at night (in) • no seasonal or solar cycle dependence

• O+ flux after: 8 -2 -1 Φday = [1+ F10.7r - (.25 + .25F10.7r)β] x10 cm s 8 -2 -1 = [1+ F10.7r - .1β] x10 cm s

8 -2 -1 Φnight = -[.5+ .7F10.7r - (.5 + .8F10.7r)β] x10 cm s 8 -2 -1 = -[.5+ .7F10.7r - .1β] x10 cm s

β=1+sin(π[(ϕ- π/8)/(π/4)]) ϕ=(d-171.25)/(π/365) -3 F10.7r= 8.3 x10 F10.7-0.67 after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 26 - Improving the TIEGCM Upper Boundary Condition

Te before Te after

Ne before Ne after

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 27 - TIEGCM/ISR Comparisons - Millstone (42.6oN, 71.5oW)

electron density

equinox

June solstice

December solstice

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 28 - TIEGCM/ISR Comparisons - Millstone (42.6oN, 71.5oW)

electron temperature

equinox

June solstice

December solstice

after Lei et al., 2006

12 May 2006 ICTP Space Weather School Maura Hagan - 29 - TIEGCM/ISR Comparisons - Millstone (42.6oN, 71.5oW)

ion temperature

equinox

June solstice

December solstice

after Lei et al., 2006

12 May 2006 ICTP Space Weather School Maura Hagan - 30 - TIEGCM/ISR Comparisons - Arecibo (18.3oN, 66.7oW)

electron density

equinox

June solstice

December solstice

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 31 - TIEGCM/ISR Comparisons - Arecibo (18.3oN, 66.7oW)

electron temperature

equinox

June solstice

December solstice

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 32 - TIEGCM/ISR Comparisons - Arecibo (18.3oN, 66.7oW)

ion temperature

equinox

June solstice

December solstice

after Lei et al., 2006 12 May 2006 ICTP Space Weather School Maura Hagan - 33 - TIEGCM Te-Ne Relationship over Millstone

MHR@ 300 km MHR 20 6 2 5 500 km 2 15 500 km Heating x Ne 3 3 " ) 0) 4 - 300 km -m 10m 11 11 10 1( 3 -

N ( Ne e e 2 Cooling x N e 5 N Cooling x Ne N " 1 + 0 0 competing processes 50 100 150 200 250 1800 2000 2200 2400 2600 2800 F107 Te (K) F10.7 Te 2200 20 ! 16 300 km ) 2000 300 km K 30) -m ( 11 12 + 1( 1800 Tee N 8 ! T ee threshold e 1600 N - 4

1400 0 + 50 100 150 200 250 1400 1600 1800 2000 2200 F107 Te (K) F10.7 Te

Electron temperature, Te, is expected to decrease with solar activity, as electron density, Ne, increases. But, Lei et al. (2006) show that .. after Lei et al., 2006

12 May 2006 ICTP Space Weather School Maura Hagan - 34 - Thermosphere-Ionosphere-Electrodynamics General Circulation Model TIEGCM Part 3: Case Studies • October-November 2003 Halloween Storms • community effort - realistic drivers - assimilated data • led by Gang Lu HAO Scientist

12 May 2006 ICTP Space Weather School Maura Hagan - 35 - Parameterization

MHD AMIE TIMED

AMIE: Aurora & Assimilative Solar EUV & UV Mapping of Convection Solar EUV & UV Ionospheric Electrodynamics TIMED: Procedure Thermosphere Ionosphere MHD: TIEGCM Mesosphere Magneto- (97-700 km) Energetics & Hydro- Dynamics Dynamic Satellite Model of the Magnetosphere

Tides GSWM: Global Scale GSWM Wave Model

12 May 2006 ICTP Space Weather School Maura Hagan - 36 - CCaassee SSttuuddiieess wwiitthh tthhee NNCCAARR//HHAAOO GGCCMMss High-Latitude Forcing

• GPI forcing: GeoPhysical Indices ⇒ Kp & F10.7 empirical convection electric fields, aurora and solar irradiance forcing • SPE forcing: Solar Proton Event ⇒ energetic particle observations (TIME-GCM) • AMIE forcing: convection electric fields and auroral forcing from assimilated ground-based and satellite observations October - November 2003 Halloween Storms

12 May 2006 ICTP Space Weather School Maura Hagan - 37 - Prevailing Space Weather: Solar Wind and IMF

12 May 2006 ICTP Space Weather School Maura Hagan - 38 - Prevailing Space Weather: Solar Wind and IMF ACE Data for October 28 – November 1, 2003

Magnetic Cloud Magnetic Cloud

…a closer look

SEP SEP 06:20 15:57

12 May 2006 ICTP Space Weather School Maura Hagan - 39 - Prevailing Space Weather: Geomagnetic Activity

12 May 2006 ICTP Space Weather School Maura Hagan - 40 - AIME Forcing Quiet Time Storm Time

12 May 2006 ICTP Space Weather School Maura Hagan - 41 - AIME Forcing

12 May 2006 ICTP Space Weather School Maura Hagan - 42 - TIEGCM Electron Column Densities on 29 October 2003

12 May 2006 ICTP Space Weather School Maura Hagan - 43 - GPS Total Electron Content

courtesy of Anthea Coster and Bill Rideout

12 May 2006 ICTP Space Weather School Maura Hagan - 44 - TIMED-GUVI Observations of Neutral Composition

Note increase in N2 at high latitudes as the storm progresses, in response to auroral heating and associated thermospheric upwelling

courtesy of Larry Paxton

12 May 2006 ICTP Space Weather School Maura Hagan - 45 - Simulated O/N2 Ratios

The GCM captures the

salient features of the O/N2 TIMED-GUVI observations

12 May 2006 ICTP Space Weather School Maura Hagan - 46 - CHAMP Neutral Density Observations at 400km

Nightside

Note, comparisons with TIEGCM in notes from Jeff Forbes’ lecture on 11 May 2006

Dayside

courtesy of Jeff Forbes and Oct 29-31 Xiaoli Zhang

12 May 2006 ICTP Space Weather School Maura Hagan - 47 - Neutral Temperature Difference at ~400 km

Disturbed - Quiet

12 May 2006 ICTP Space Weather School Maura Hagan - 48 - TIEGCM Neutral Temperature Difference at ~400 km Oct 30 1820UT Oct 30 1920UT Oct 30 2120UT 1700 ) K o (

N T Δ

Oct 30 2220UT Oct 30 2320UT Oct 31 0020UT 1700 ) K o (

N T Δ

0 12 May 2006 ICTP Space Weather School Maura Hagan - 49 - TIEGCM Diagnostics - Thermosphere October 28 – November 2, 2003 ) W G (

H J

60 % 50 %

20 %

-20 %

-60 ~ 80 %

12 May 2006 ICTP Space Weather School Maura Hagan - 50 - TIEGCM Diagnostics - Ionosphere

October 28 – November 2, 2003

Quiet-time value

- 70 %

12 May 2006 ICTP Space Weather School Maura Hagan - 51 - Recap - Halloween Storm Simulation

• Strong geomagnetic activity with Dst ~ - 450 nT, AE ~ 3500 nT; cross-polar-cap potential drop reaches 350 ~ 400 kV, and Joule heating peaks ~ 5000 GW • Solar energetic protons produce significant ionization in the D- region, causing enhanced riometer absorption in both northern and southern polar regions in TIME-GCM

• Large Joule heating dissipation increases TN in the thermosphere by 700oK (global average), and reaches ~1700oK in local regions

• Significant decrease of O/N2 ratio in the middle latitude region and auroral and subauroral zones

• The global average HmF2 increased by more than 100 km and NmF2 decreased by 70%

12 May 2006 ICTP Space Weather School Maura Hagan - 52 - Other GCM Development Efforts • TIME-GCM (ca. 1992) – moved lower boundary down to 30km – added stratospheric and mesospheric constituents and chemistry – added parameterized gravity wave effects • Ongoing – adding a self-consistent plasmasphere – contributing to the Center for Integrated Space Weather Modeling (CISM) effort – working with other NCAR scientists to extend the Whole Atmosphere Community Climate Model (WACCM) into the thermosphere

12 May 2006 ICTP Space Weather School Maura Hagan - 53 - Extra Slides: Plasmaspheric Model Development SEP during Halloween Storms

12 May 2006 ICTP Space Weather School Maura Hagan - 54 - Plasmasphere Model Development Plan

LFM Global Global Electric Magnetospheric Potential Solver Model

Neutral Wind Electric Field

Conductivity Plasma Rice Interactions Convection Plasmasphere Model Model He+, H+ (e-, O+, He+, H+) He, H

Exosphere (H, He) O e-, O+ Auroral Precipitation and Convection TIEGCM: Thermosphere-Ionosphere

12 May 2006 ICTP Space Weather School Maura Hagan - 55 - 12 May 2006 ICTP Space Weather School Maura Hagan - 56 - Solar Energetic Protons Observed by NOAA-POSE

00 UT, 28 October 2003

107 30-80 keV 80-240 keV 240-800 keV sec - 2 Protons/cm

1 104 2.5-6.9 MeV 6.9-16 MeV 16-35 MeV sec - 2 Protons/cm

10-2

12 May 2006 ICTP Space Weather School Maura Hagan - 57 - Solar Energetic Protons Observed by NOAA-POSE 06 UT, 29 October 2003

7 30-80 keV 80-240 keV 240-800 keV 10 sec - 2 Protons/cm

1 4 2.5-6.9 MeV 6.9-16 MeV 16-35 MeV 10 sec - 2 Protons/cm

10-2

12 May 2006 ICTP Space Weather School Maura Hagan - 58 - Electron Density Enhancement due to SEP

Oct 28 Oct 29 Oct 30 Oct 31 Nov 1 Oct 28 Oct 29 Oct 30 Oct 31 Nov 1

12 May 2006 ICTP Space Weather School Maura Hagan - 59 -