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TOWARDS A REALISTIC, DATA-DRIVEN THERMODYNAMIC MHD MODEL OF THE GLOBAL SOLAR CORONA

TOWARDS A REALISTIC, DATA-DRIVEN THERMODYNAMIC MHD MODEL OF THE GLOBAL SOLAR CORONA. Cooper Downs, Ilia I. Roussev , Bart van der Holst , Noe Lugaz , Igor V. Sokolov , and Tamas I. Gombosi arXiv:0912.2647 submitted 12/08/2009 to ApJ. Abstract.

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TOWARDS A REALISTIC, DATA-DRIVEN THERMODYNAMIC MHD MODEL OF THE GLOBAL SOLAR CORONA

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  1. TOWARDS A REALISTIC, DATA-DRIVEN THERMODYNAMIC MHD MODEL OF THE GLOBAL SOLAR CORONA Cooper Downs, Ilia I. Roussev, Bart van derHolst, NoeLugaz, Igor V. Sokolov, and Tamas I. Gombosi arXiv:0912.2647 submitted 12/08/2009 to ApJ

  2. Abstract • They implemented a thermodynamic energy equation into the global corona model. • They compared the model results to full sun EUV and soft X-Ray observations. • They found that a relative simple empirical heating model is adequate in reproducing structures observed in the low corona. • They showed that the interplay between coronal heating and electron heat conduction provides significant feedback onto the 3D magnetic topology in the low corona.

  3. Coronal Heating Problem • How the solar corona can be heated to 1MK? • Wave or nanoflare? • Hinode • Temperature structure in coronal loop(Tripathi et al. 2009, Kano et al. 2008) • Heating at footpoint of AR loop (Hara et al. 2008) • Timescale of nanoflare (Terzo) • Upflow in plage (Imada et al. 2007) • High temperature plasma (Reale et al. 2009, Ishibashi et al.) • Many simulations • Antolin, P. PhD Thesis • Matsumoto, T. PhD Thesis

  4. Parameterized heating • It is difficult to include the small-scale micro physics of plasma responsible for coronal heating in 3D models. • As a result, heating models are often parameterized as a heating term that depends on various local magnetic and thermodynamic properties that is included in the energy equation. • There are the large number of ad-hoc heating models (e.g. Aschwanden & Schrijver (2002); Schrijver et al. (2004); Abbett (2007); Mok et al. (2008)).

  5. Data driven approach • Constraining physical theories and scenarios through as many observable manifestations available is important. • They modify the global corona model of the Space Weather Modeling Framework (Toth et al. 2005) to include the transition region between the chromosphere and the corona. • The now relevant non-MHD terms (radiation, heat conduction, and coronal heating) are added to the MHD energy equation.

  6. 2. The simulation Tool • They use Space Weather Modeling Framework (SWMF) Solar Corona model (Cohen et al. 2007) and Wang-Sheeley-Arge (WSA) model (Arge et al. 2004). • The advantage of this tool is its ability to simulate the complete 3D environment of any event and Carrington Rotation. • The initial magnetic configuration is extrapolated using the Potential Field Source Surface Method (Altschuler et al. 1977).

  7. 2.2. Including Additional Thermodynamic Terms • Heat conduction • Radiative Loses • Heating Model 1 • Heating Model 2 Total unsigned magnetic flux at the solar surface Local heating weighting function Constant

  8. 2.2. Including Additional Thermodynamic Terms • Coronal hole heating • Open field cutoff • Open field (coronal hole) => only “coronal hole heating” is applied • Closed field => both are applied

  9. 2.3. Boundary Conditions • Chromosphericboundary • Chromospheric values are set to be • Broadening method in transition region • Radiative Energy Balance (REB) Model • In high transition region,

  10. 2.4. Geometric Considerations • Sun-centered 48x48x48Rsun cube. • Average cell size is smallest at the surface (~7000km). • The block-adaptive mesh and adaptive mesh refinement capability.

  11. 3. Model Runs • MDI magnetogram, CR 1913, centered on Aug 27, 1996. • Solar minimum. • Compared with SOHO EIT(171, 195, and 284A), and Yohkoh SXT observation.

  12. Run A Run B Run C Run D Observation

  13. Run C and D Run C (Uniform Heating) Run D (Exponential + AR Heating) This result suggests a complex relationship both between the thermodynamics of the low corona and the global structure of the solar wind.

  14. 4. Detailed analysis (Run D) Run D (Exponential Heating + AR heating) Yohkoh SXT AlMg response

  15. PFSSM (Altschuler et al. 1977) Standard SC model (Cohen et al. 2007) Run D

  16. Standard SC model (Cohen et al. 2007) Run D Obs.

  17. Temperature Distribution Standard SC model (Cohen et al. 2007) Run D R=1.01 R=1.03 R=1.10

  18. Electron Density Distribution Standard SC model (Cohen et al. 2007) Run D R=1.01 R=1.03 R=1.10

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