The MHD simulation of the inner heliosphere over 9 years using the observation-based time-varying boundary data.

摘要

The evolution of the inner heliosphere over a 9-year period from 2001 to 2009, from 50 R_s to 1250 R_s, is simulated by means of the time-dependent three-dimensional MHD simulation with a new treatment handling the observation-based temporally evolving boundary data. The inner boundary magnetic field is calculated from the solar surface magnetic field data made at Wilcox Solar Observatory (WSO), and the plasma speed data is from the maps constructed by means of the MHD tomography analysis using the interplanetary scintillation (IPS) data. The density and temperatures are determined by empirical relation functions that are derived from Helios data. In this way, all inner boundary values of the solar wind flowing outward are from measurements. The two ground-based observations, WSO magnetic field and IPS solar wind data, have been long conducted, and we used these two dataset to drive the simulation system over the 9-year span well covering the solar cycle 23. The simulated interplanetary MHD variables are compared with the in-situ measurements, OMNI (nearby the Earth) and the Ulysses. Overall, except the poloidal component of the magnetic field, the simulated MHD variables derived agree very well with the in-situ data.