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Simulating a Solar CycleSimulating a Solar Cycle

• My impetus (in addition to this GEM-FG):My impetus (in addition to this GEM-FG):– Attended 2 CDAWs (2005, 2007) on large Attended 2 CDAWs (2005, 2007) on large

geomagnetic stormsgeomagnetic storms– Examined all intense storms (DstExamined all intense storms (Dstminmin ≤ -100 nT) ≤ -100 nT)

for solar cycle 23 (1996-2005)for solar cycle 23 (1996-2005)– Considered solar sources and geospace Considered solar sources and geospace

consequencesconsequences• Getting diverse communities to talk to each otherGetting diverse communities to talk to each other

• Challenge issued to modelers: Challenge issued to modelers: – Simulate all of these eventsSimulate all of these events

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MethodologyMethodology

• Run HEIDI for all 90 eventsRun HEIDI for all 90 events– HEIDI: Hot Electron and Ion Drift IntegratorHEIDI: Hot Electron and Ion Drift Integrator– Formerly known as the Michigan version of Formerly known as the Michigan version of

RAM (Fok et al., 1993; Jordanova et al., 1996)RAM (Fok et al., 1993; Jordanova et al., 1996)

• Choose a very simplistic set-upChoose a very simplistic set-up– Dipole magnetic fieldDipole magnetic field– Volland-Stern electric field (shielded, Kp driven)Volland-Stern electric field (shielded, Kp driven)– LANL moments for outer boundary conditionLANL moments for outer boundary condition– Just the major species: HJust the major species: H++ and O and O++

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Data-Model ComparisonsData-Model Comparisons

• Limit it to only Dst* for this initial studyLimit it to only Dst* for this initial study

• Definition of "observed Dst*":Definition of "observed Dst*":

• Definition of "simulated Dst*":Definition of "simulated Dst*":

€

Dst* =Dst −DMP + DQ

CIC

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DstDPS* nT[ ] = −3.98 ⋅10−30ERC keV[ ]

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Intense Storms of Solar Cycle 23Intense Storms of Solar Cycle 23

• The numbers: The numbers: – 90 storms in all (1996-2005)90 storms in all (1996-2005)– 79 storms with "good" main phase LANL data79 storms with "good" main phase LANL data– Zhang et al. [JGR, 2007] published solar sources Zhang et al. [JGR, 2007] published solar sources

of all 90 eventsof all 90 events• Jie Zhang of GMU, Jie Zhang of GMU, notnot Jichun Zhang my PhD student Jichun Zhang my PhD student

Event Totals W ith Respect to Driver Classification 1 2 All Events CIR ICME Sheath MC Ejection Complex 3 4 Entire storm list 90 11 79 22 33 12 12 5 Good-data list 79 10 69 21 26 11 11 6

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Data-Model StatisticsData-Model Statistics

• Remember, the only data is Dst*Remember, the only data is Dst*Average Values of Sim ulation Results 1

2 Parameter All Events CIR ICME Sheath MC Ejection Complex 3 4 DPSmin -100 -52 -108 -144 -84 -92 -109 5 DPS/Dst*min 0.78 0.55 0.81 1.05 0.63 0.83 0.76 6 <DPS/Dst*> 0.87 0.66 0.90 1.13 0.75 0.87 0.85 7 Pmax 217 101 233 338 174 189 219 8 Pavg 101 47 108 158 81 84 105 9 Pmax/Pmin 102 62 108 115 81 159 104 10

P/Pavg 2.10 2.04 2.11 2.08 2.08 2.20 2.15 11

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More on Data-Model StatisticsMore on Data-Model Statistics

• Let's look at some of the numbersLet's look at some of the numbersAverage Values of Sim ulation Results 1

2 Parameter All Events CIR ICME Sheath MC Ejection Complex 3 4 DPSmin -100 -52 -108 -144 -84 -92 -109 5 DPS/Dst*min 0.78 0.55 0.81 1.05 0.63 0.83 0.76 6 <DPS/Dst*> 0.87 0.66 0.90 1.13 0.75 0.87 0.85 7 Pmax 217 101 233 338 174 189 219 8 Pavg 101 47 108 158 81 84 105 9 Pmax/Pmin 102 62 108 115 81 159 104 10

P/Pavg 2.10 2.04 2.11 2.08 2.08 2.20 2.15 11

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7

V-S E-field V-S E-field and the ring and the ring

currentcurrent• V-S driving V-S driving

systematically systematically underestimates the underestimates the observed Dst*observed Dst*– Note: Dst* includes CNote: Dst* includes CICIC

– Sheath storms are Sheath storms are better than other driver better than other driver categoriescategories

• Esp. for large eventsEsp. for large events

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DPS/Dst* vs DPS/Dst* vs Dst*Dst*

• Here is a better plot Here is a better plot – Underestimation is Underestimation is

clearly seenclearly seen

• Not the same as Not the same as previous plot:previous plot:– This is for a 12-h This is for a 12-h

average (pre-peak) average (pre-peak) for each stormfor each storm

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DPS and InputDPS and Input

• Input function:Input function:– A(kp) * NcorrA(kp) * Ncorr– Good measure of Good measure of

the resulting ring the resulting ring current intensity in current intensity in the codethe code

– Esp. for CIR-driven Esp. for CIR-driven and MC-driven and MC-driven eventsevents

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Some ExplanationSome Explanation

• Young et al. [1982] composition formula:Young et al. [1982] composition formula:

• NNcorrcorr: N: NMPAMPA corrected for composition corrected for composition

• Input function: estimate of ring current Input function: estimate of ring current source termsource term

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ζY 82 =nO+ ,Y 82

nH + ,Y 82

= 0.032exp 0.186Kp+ 0.011F10.7( )

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ncorr = nMPA1+ζY 82

1+ 14ζY 82

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Input function = I = A ⋅ncorr

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Maynard and Chen ConvectionMaynard and Chen Convection

• Kp-driven shielded Volland-Stern 2-cell Kp-driven shielded Volland-Stern 2-cell convection from Maynard and Chen [1975]convection from Maynard and Chen [1975]

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A =0.045

1.− 0.159Kp+ 0.0093Kp2( )

3 kV

RE2

⎡

⎣ ⎢

⎤

⎦ ⎥

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DPS and DPS and either input either input

by itselfby itself• Not nearly as Not nearly as

good as the good as the combined input combined input functionfunction– Esp. for sheath-Esp. for sheath-

driven stormsdriven storms– Kp: plots have a Kp: plots have a

kink near -70 nTkink near -70 nT– Above this, Kp Above this, Kp

is uncorrelatedis uncorrelated

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DPS and DPS and CompositionComposition

• Two trends in all plots:Two trends in all plots:– Smaller than -170 nT:Smaller than -170 nT:

• UncorrelatedUncorrelated• Most values < unityMost values < unity

– Larger than -200 nT:Larger than -200 nT:• Still uncorrelatedStill uncorrelated• Most values > unityMost values > unity

– Is OIs O++ dominance dominance necessary for large Dst necessary for large Dst events?events?

• Plots imply this to be the Plots imply this to be the case...case...

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Conclusions on VS-driven HEIDIConclusions on VS-driven HEIDI• Works well for sheath-driven stormsWorks well for sheath-driven storms

– Inner magnetosphere simple for these storms?Inner magnetosphere simple for these storms?

• Not so good for CIR- or MC-driven stormsNot so good for CIR- or MC-driven storms– Longer events...internal feedback important?Longer events...internal feedback important?

• Kp-DPS correlations have a kinkKp-DPS correlations have a kink– Driving saturates and other terms control Dst?Driving saturates and other terms control Dst?

• OO++/H/H++-DPS correlations are bimodal-DPS correlations are bimodal– HH++ dominates for DPS dominates for DPSminmin > -170 nT, O > -170 nT, O++ for bigger for bigger

stormsstorms– O+ necessary for large events?O+ necessary for large events?

• Local time asymmetry not dependent on driverLocal time asymmetry not dependent on driver– Probably due to constancy of the VS potential patternProbably due to constancy of the VS potential pattern

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Extra SlidesExtra Slides

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Data AnalysisData Analysis

• Results even before we run the codeResults even before we run the codeAverage Values of Inp uts and Data 1

2 Parameter All Events CIR ICME Sheath MC Ejection Complex 3 4 Dst*min -128 -93 -133 -145 -133 -108 -134 5 <Kp> 5.81 4.88 5.94 6.00 6.04 5.75 5.78 6 <A> 1.24 0.90 1.29 1.33 1.32 1.24 1.22 7 <F10.7> 156 128 160 177 151 130 180 8 <[O+]/[H+]> 0.66 0.35 0.70 0.85 0.67 0.44 0.77 9 <NMPA> 1.47 1.39 1.48 1.72 1.29 1.49 1.48 10 <TMPA> 7.38 7.69 7.34 7.12 7.57 7.70 6.87 11 <Ncorr> 2.13 1.74 2.19 2.68 1.85 1.95 2.29 12 <Input function> 3.13 1.72 3.33 4.26 2.87 2.82 3.15 13

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More on Data AnalysisMore on Data Analysis

• Let's look at some interesting numbersLet's look at some interesting numbersAverage Values of Inp uts and Data 1

2 Parameter All Events CIR ICME Sheath MC Ejection Complex 3 4 Dst*min -128 -93 -133 -145 -133 -108 -134 5 <Kp> 5.81 4.88 5.94 6.00 6.04 5.75 5.78 6 <A> 1.24 0.90 1.29 1.33 1.32 1.24 1.22 7 <F10.7> 156 128 160 177 151 130 180 8 <[O+]/[H+]> 0.66 0.35 0.70 0.85 0.67 0.44 0.77 9 <NMPA> 1.47 1.39 1.48 1.72 1.29 1.49 1.48 10 <TMPA> 7.38 7.69 7.34 7.12 7.57 7.70 6.87 11 <Ncorr> 2.13 1.74 2.19 2.68 1.85 1.95 2.29 12 <Input function> 3.13 1.72 3.33 4.26 2.87 2.82 3.15 13

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Dst and InputDst and Input

• Some correlation, Some correlation, but not perfectbut not perfect– Less good relative Less good relative

to DPS-to-Inputto DPS-to-Input

• Final Dst depends Final Dst depends on both in a on both in a complicated waycomplicated way– Time historyTime history– Double rings occurDouble rings occur

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Ring Current Simulations of Ring Current Simulations of the Storms of Solar Cycle 23the Storms of Solar Cycle 23

Mike LiemohnMike Liemohn

University of MichiganUniversity of Michiganto GEM Space Radiation Climatology Focus Group to GEM Space Radiation Climatology Focus Group

June 26, 2008June 26, 2008