Data-constrained Simulation of CME Initiation and Propagation Antonia Savcheva ESPM 2014 September 11, 2014 Collaborators: R. Evans, B. van der Holst, Y.Su, E. DeLuca 1

Outline  Motivation  The flux rope insertion method  The 8 April 2010 CME  SWMF and AWSoM  Simulation set-up  Results from the simulations  Conclusions 2

Motivation 3  CME 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 4  First CME observed by AIA; Hinode, STEREO data

NLFFF modeling The flux rope insertion method  van 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) 5

Models 8 April 2010 region 6  Modeled by Su et al. (2011) and Kliem at al. (2013) - studied stability boundary  Models with different axial flux – 4x x10 20 Mx  Unstable model with axial flux > 5x10 20 Mx Su et al. (2011)

The Space Weather Modeling Framework (SWMF) and AWSoM 7  SWMF uses BATS-R-US global MHD code  Boundary conditions – prescribed or synoptic magnetogram  Initial condition – prescribed TD of GL flux ropes, or NLFFFs  AMR, thermodynamics, resistive or ideal MHD, etc.  AWSoM – Alfven Wave Solar Model (van der Holst et al. 2014)  Starts at top of chromosphere  Stratified atmosphere  Heating by dissipation of of Alfven waves by  Reflection  Turbulent cascade

Setting-up the initial condition 8  Incorporate 3D grid of partial sun NLFFF model – potential field = difference field with open boundaries  Potential Source Surface Model + add potential field to difference field  Run stead state solar wind model  Set up AMR and initiate eruption in the SS SW

Comparison of CME with different initial conditions 9  Models with: 1) Different axial flux; 2) axial flux = 9x10 20 Mx with different scaling of the NLFFF-potential field 4x x x x x x10 20 x1.25 9x10 20 x2

The scaled model (NLFFF x 2) 10 Density ratio Radial Velocity

Comparison with a TD model 11 Same orientation and size of the initial J contour, free energy Similar but: Morphology differences Speed differences Average front velocity: NLFFF I.C. = 1230 km/s TD I.C. = 2000 km/s NLFFF TD

Height-time and velocity-time plots 12  Measure where density is 4% above background -> get front of CME, measure velocity of front 9x10 20 x 2 9x10 20 x 1.25 TD corr. 9x10 20 x2

Conclusions and future work 13  The first data-constrained global CME simulation from realistic initial and boundary conditions  Explored the effect of the initial condition’s axial flux on the CME properties  Compared to a TD idealized simulation and showed differences  Computed height-time and velocity-time plots  Future:  Compare the H-t, V-t plots and simulated white light images to observations  Propagate a geoeffective CME to 1AU and simulate signatures at Earth and STEREO – 7 Aug 2010

Thank you! 14