Merging of coronal and heliospheric numerical two-dimensional MHD models D. Odstrcil, et al., J....
-
date post
21-Dec-2015 -
Category
Documents
-
view
217 -
download
4
Transcript of Merging of coronal and heliospheric numerical two-dimensional MHD models D. Odstrcil, et al., J....
Merging of coronal and heliospheric numerical two-dimensional MHD models
D. Odstrcil, et al., J. Geophys. Res., 107, 2002.
2004 年 10 月 14 日 太陽雑誌会 ( 速報 ) 西田
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.
Numerical Models
• Coronal Model– 2-D axisymmetric resistive MHD equations– Semi-implicit finite difference scheme using st
aggered values
• Heliospheric Model– 2-D axisymmetric ideal MHD equations– Explicit finite difference total-variation-diminis
hing high-resolution Lax-Friendrichs (TVDLF) scheme using cell-centered values
• Merged numerical grid
Fig. 1
• Coronal Model– 200x300 grid points– Nonuniform mesh for th
e streamer
• Heliospheric Model– 340x240 grid points
• The output from the coronal model is used as a boundary condition for the heliospheric solutions
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.
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.
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.