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Merging of coronal and heliospheric numerical two-dimensional MHD models

This paper presents a demonstration of merged coronal and heliospheric 2-D MHD models for simulating transient disturbances in space weather research. The merging of models allows for the simulation of solar wind and magnetic parameters at 1 AU, providing input for geo-effectivity models.

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Merging of coronal and heliospheric numerical two-dimensional MHD models

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  1. 2004年10月14日 太陽雑誌会(速報) 西田 Merging of coronal and heliospheric numerical two-dimensional MHD models D. Odstrcil, et al., J. Geophys. Res., 107, 2002.

  2. Introduction • Space weather research involves a chain of various phenomena occurring simultaneously on different spatial and temporal scales. • An integrated modeling approach is necessary for space weather research. • This paper presents a demonstration of merged coronal and heliospheric 2-D MHD models.

  3. Numerical Models • Coronal Model • 2-D axisymmetric resistive MHD equations • Semi-implicit finite difference scheme using staggered values • Heliospheric Model • 2-D axisymmetric ideal MHD equations • Explicit finite difference total-variation-diminishing high-resolution Lax-Friendrichs (TVDLF) scheme using cell-centered values

  4. Coronal Model • 200x300 grid points • Nonuniform mesh for the streamer • Heliospheric Model • 340x240 grid points • The output from the coronal model is used as a boundary condition for the heliospheric solutions • Merged numerical grid Fig. 1

  5. Ambient State in the corona Fig. 2

  6. Ambient State in the heliosphere Fig. 3

  7. Fig. 4. Blue: 70°, Red: 80°, Black: 90°

  8. Transient Disturbances • The streamer products strongly sheared field lines that are nearly aligned with the neutral line; it is just a convenient mechanism. • The sharing phase lasts 5.2 days. • We reduce the magnetic flux at the photosphere to create a flux rope. • After ~18 hours the arcade erupts.

  9. http://sprg.ssl.berkeley.edu/cism/

  10. Fig. 5

  11. Fig. 6. Blue: 70°, Red: 80°, Black: 90°

  12. Fig. 7

  13. Fig. 8

  14. Fig. 9

  15. Fig. 10 . Blue: 70°, Red: 80°, Black: 90°

  16. Conclusions (1/2) • The merging of coronal and heliospheric MHD models has been successfully implemented for a 2-D ambient state and a transient disturbance. • Different mathematical models, numerical methods, and computational grids were used in this work, and thus the merging of the numerical models was demonstrated for a quote general case.

  17. Conclusions (2/2) • Merged coronal and heliospheric models have enabled the simulation of transient disturbances. • The solar wind and magnetic parameters at 1 AU resulting from the coupled computations can provide input for geo-effectivity models.

  18. Fig. A1

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