The role of cmes in the solar cycle and evidence for a floor in the open magnetic flux
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The role of CMEs in the solar cycle and Evidence for a Floor in the Open Magnetic Flux. Nathan Schwadron, N. Crooker, M. J. Owens, C. W. Smith, D. E. Connick, T. S. Horbury, O. C. St Cyr, N. Gopalswamy, S. Yashiro, H. Xie. The Helisphere’s Hale Cycle. N- S+. N+ S-. N- S+. N- S+. N+

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The role of CMEs in the solar cycle and Evidence for a Floor in the Open Magnetic Flux

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The role of cmes in the solar cycle and evidence for a floor in the open magnetic flux

The role of CMEs in the solar cycle and Evidence for a Floor in the Open Magnetic Flux

Nathan Schwadron,

N. Crooker, M. J. Owens, C. W. Smith, D. E. Connick, T. S. Horbury, O. C. St Cyr, N. Gopalswamy, S. Yashiro, H. Xie


The helisphere s hale cycle

The Helisphere’s Hale Cycle

N-

S+

N+

S-

N-

S+

N-

S+

N+

S-


Evolving magnetic flux

Evolving Magnetic Flux

N+

S-

N-

S+

N+

S-

Roughly factor x2 variation

in Open Magnetic Flux

N-

S+

N+

S-

N+

S-

Wang et al., 2000


The role of cmes

The Role of CMEs

CMEs move flux via interchange reconnection

CMEs temporarily add closed magnetic flux, increasing |B|, particularly during solar max


Temporary flux addition by cmes

Temporary Flux Addition by CMEs

Black line shows the observed value of |B| at 1 AU from ACE/Wind

Red line shows simulated value of |B| at 1 AU using LASCO observed CME rates

CME half-life 50 days

Model comparison validates open flux conservation during CME ejections


Cmes and the hale cycle

CMEs and the Hale Cycle

  • CMEs generally have an orientation in agreement in with Hale’s law (Bothmer and Schwenn, Ann. Geophys., 1998)

  • Is the flux opened by Interchange Reconnection sufficient for field reversal?

    • Fopen = Open Flux ~1015 Wb

    • FCME=CME flux ~1012 Wb

    • freq = CME frequency ~ 3/day

    • d = CME footpoint separation

  • Number of Needed CMEs,

  • N =(Fopen/FCME)x(180o/d)

  • Time required for field reversal,

  • T = N/freq ≈ 11 years

  • Solve for footpoint separation

  • d > 5o


The role of cmes in the solar cycle and evidence for a floor in the open magnetic flux

Owens et al., 2006


The role of cmes in the solar cycle and evidence for a floor in the open magnetic flux

Cohen et al, 2009 – See Poster


Cme rate field correlation

CME rate – field correlation

Owens et al., 2008


Cme rate b correlation

CME-rate |B| correlation

Owens et al., 2008


Model of cme b correlation

Model of CME-|B| Correlation

  • |B| Floor of ~ 4 +/- 0.3 nT

  • Δ|B|min~ 0.5 nT (change from this to last min)

  • Accounted for by model if

    • Ejected CME flux of 1-2 x 1013 Wb

    • IC Reconnection time of ~30-50 days

    • Lowers the needed to footpoint separation to > 1 deg

Owens et al., 2008


The observed toroidal ejection rates

The Observed Toroidal Ejection Rates

  • Limits on the flux ejected by CMEs

    • Lower limit of 1x1023 Mx/yr (3x1012 Wb/dy) from Schwadron et al., 2008 based on open flux increase near max

    • Upper limit of 5.5x1023 Mx/yr (16x1012 Wb/dy) from Connick et al. based toroidal ejection rate

    • Owens et al. 2008 finds 1-2x1013 Wb ejected at a rate of 0.5/day => 5-10x1012 Wb/dy

Connick, Smith, Schwadron 2008 (See Poster)


Interchange reconnection mass and energy supply

Interchange Reconnection: Mass and Energy Supply

  • Reconnection leads to 2 beams

  • Loop beam empties loop material into solar wind at Aflven speed

  • SW beam leads to incoming rain from the solar wind

  • Some electron heating

SW

beam

Exhaust

t2

Loop

beam

va

opening

loop

t1

va

va

x

t0


Flux flux scaling

Flux-Flux Scaling

Injected Elec.Mag. Energy/Particle

Constant injected energy/particle implies injected power proportional to particle flux and magnetic flux:

Injected Power proportional to magnetic flux


Solar wind power and mass flux decreases with time

Solar Wind Power and Mass Flux Decreases with Time


Long term evolution

Long-Term Evolution

  • Evidence of Open Flux Conservation over Large Timescales (Svalgaard and Cliver, 2007)


Http cor1 gsfc nasa gov

http://cor1.gsfc.nasa.gov

>400 CMEs

SOHO LASCO CME Rate in 1996-1997 was ~0.5 CMEs/day

Preliminary CME Catalogue

St. Cyr (Jan-Aug 2007)

Hong Xie (Sep 2007-Sep2008)

St. Cyr & Xie (Oct 2008-Jun2009)


Soho lasco cme rate

SOHO LASCO CME Rate


Cmes and the solar cycle

CMEs and the Solar Cycle

  • Clear Correlation between Open Field Flux and CME rate

  • Clear evidence for Interchange Reconnection

  • IR with CMEs should help achieve the reversal

  • Recent observations suggest consistent limits on flux ejection by CMEs

  • The observed ejection rates easily support reversal over the 11 year solar cycle

  • We are now in a prolonged depression in open field strength, ejection rate, solar wind mass flux and solar wind power

    • These are all likely regulated through interchange reconnection with CMEs


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