Development of the 3‐D MHD model of the solar corona‐solar wind combining system

Abstract

[1] In the framework of integrated numerical space weather prediction, we have developed a 3-D MHD simulation model of the solar surface-solar wind system. We report the construction method of the model and its first results. By implementing a grid system with angularly unstructured and increasing radial spacing, we realized a spherical grid that has no pole singularity and realized a fine grid size around the inner boundary and a wide-range grid up to a size of 1 AU simultaneously. The magnetic field at the inner boundary is specified by the observational data. In order to obtain the supersonic solar wind speed, parameterized source functions are introduced into the momentum and energy equations. These source functions decay exponentially in altitude as widely used in previous studies.The absolute values of the source functions are controlled so as to reflect the topology of the coronal magnetic field. They are increased inside the magnetic flux tube with subradial expansion and reduced inside the magnetic flux tube with overradial expansion. This adjustment aims to reproduce the variation of the solar wind speed according to the coronal magnetic structure. The simulation simultaneously reproduces the plasma-exit structure, the high-and low-temperature regions, the open and closed magnetic field regions in the corona, the fast and slow solar wind, and the sector structure in interplanetary space. It is confirmed from the comparison with observations that the MHD model successfully reproduces many features of both the fine solar coronal structure and the global solar wind structure.

The magnetic field in the solar atmosphere

“…Small-scale features as well as plasma emission from open field lines anchored in polar regions have not been recovered. Advanced MHD techniques have been used to successfully model the variation of the solar wind speed Hu et al 2008;Nakamizo et al 2009;Yang et al 2007. This includes the fast and slow solar wind, the sector structure of the interplanetary magnetic field as well as the shape and location of CHs (see Sect.…”

THREE-DIMENSIONAL SOLARWINDMODELING FROM THE SUN TO EARTH BY A SIP-CESE MHD MODEL WITH A SIX-COMPONENT GRID

“…This is a feature common to the grid mesh in the spherical shell. Even if the numerical schemes are implemented in Cartesian or cylindrical coordinates (Tanaka 1994(Tanaka , 1995(Tanaka , 1999(Tanaka , 2000Groth et al 2000;Cohen et al 2008;Feng et al 2007; Hu et al 2008; Kleimann et al 2009; Nakamizo et al 2009), the computational domain used in solar wind modeling has to approximate the spherical shell geometry.…”

Evolution of Coronal Mass Ejection Morphology With Increasing Heliocentric Distance. Ii. In Situ Observations

“…While these techniques may attempt to deduce the size and orientation of the ICME, the shape is often an explicit assumption of the model used. MHD simulations (e.g., Riley et al 2001;Manchester et al 2004;Odstrcil et al 2004;Lugaz et al 2005;Kataoka et al 2009;Nakamizo et al 2009;Shiota et al 2010) and interplanetary scintillation (IPS) studies (Jackson et al 2007) have also significantly increased our understanding of Figure 1. Schematic displaying the relationship between Earth's bow shock and characteristics of an ICME.…”