Modeling solar active regions with flux ropes

Data-constrained Simulation of CME Initiation and PropagationAntonia SavchevaESPM 2014

September 11, 2014

Collaborators: R. Evans, B. van der Holst, Y.Su, E. DeLuca

1OutlineMotivationThe flux rope insertion methodThe 8 April 2010 CMESWMF and AWSoMSimulation set-upResults from the simulationsConclusions2Motivation3CME studies:Static non-linear force-free field (NLFFF) modeling ( e.g. Savcheva & van Ballegooijen 2009, Savcheva et al. 2014)Idealized simulation with prescribed initial and/or boundary conditions (e.g. Aulanier et al. 10, Lugaz et al.13)Data-constrained MHD simulations (first by Kliem et al. 2013, partial box)Need data-constrained and data-driven simul. of CMEs

8 April 2010 region - observations 4First CME observed by AIA; Hinode, STEREO data

NLFFF modelingThe flux rope insertion methodvan Ballegooijen (2004) the Coronal Modeling System (CMS)Potential field extrapolation (data)Insert flux rope along a filament (model)Relax to force-free state using magnetofriction (model)Make a grid of models, then match to observed coronal loops (data)

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Models 8 April 2010 region6Modeled by Su et al. (2011) and Kliem at al. (2013) - studied stability boundaryModels with different axial flux 4x1020 - 11x1020 MxUnstable model with axial flux > 5x1020 Mx

Su et al. (2011)

The Space Weather Modeling Framework (SWMF) and AWSoM 7SWMF uses BATS-R-US global MHD codeBoundary conditions prescribed or synoptic magnetogramInitial condition prescribed TD of GL flux ropes, or NLFFFsAMR, thermodynamics, resistive or ideal MHD, etc.AWSoM Alfven Wave Solar Model (van der Holst et al. 2014)Starts at top of chromosphereStratified atmosphereHeating by dissipation of of Alfven waves byReflectionTurbulent cascade

Setting-up the initial condition8Incorporate 3D grid of partial sun NLFFF model potential field = difference field with open boundariesPotential Source Surface Model + add potential field to difference fieldRun stead state solar wind modelSet up AMR and initiate eruption in the SS SW

Comparison of CME with different initial conditions9Models with: 1) Different axial flux; 2) axial flux = 9x1020 Mx with different scaling of the NLFFF-potential field 4x1020 5x1020 6x1020

7x1020 9x1020 9x1020x1.25 9x1020x2

The scaled model (NLFFF x 2)10

Density ratio Radial VelocityComparison with a TD model11

Same orientation and size of the initial J contour, free energySimilar but:Morphology differencesSpeed differencesAverage front velocity: NLFFF I.C. = 1230 km/sTD I.C. = 2000 km/s NLFFF TDHeight-time and velocity-time plots12Measure where density is 4% above background -> get front of CME, measure velocity of front9x1020 x 2 9x1020 x 1.25 TD corr. 9x1020 x2

Conclusions and future work13The first data-constrained global CME simulation from realistic initial and boundary conditionsExplored the effect of the initial conditions axial flux on the CME propertiesCompared to a TD idealized simulation and showed differencesComputed height-time and velocity-time plotsFuture: Compare the H-t, V-t plots and simulated white light images to observationsPropagate a geoeffective CME to 1AU and simulate signatures at Earth and STEREO 7 Aug 2010

Thank you!14