Solar Cycle Variations and the Large-Scale Structure of the Heliosphere: MHD Simulations
Abstract
We present time-dependent, three-dimensional MHD computations of the large-scale structure of the solar corona and heliosphere (out to 5 AU). The primary input to the model is the observed line-of-sight component of the photospheric magnetic field. We investigate several time periods to illustrate variations in heliospheric structure during different phases of the solar cycle. In particular, we emphasize structure at the maximum of the solar activity cycle. We compare the results of the simulations with Ulysses and WIND in situ observations and interplanetary scintillation measurements. We find that the simulations can reproduce the overall large-scale features of the observations and we use the results to speculate on the nature of the high-latitude solar wind that Ulysses will likely encounter during its polar passes in 2000 and 2001. Our results suggest that, due to the presence of equatorial coronal holes, the ordered pattern of CIR tilts and their associated shocks, which was observed during Ulysses initial southward excursion in 1992, will likely disappear as Ulysses traverses toward higher latitudes. We anticipate that while Ulysses will continue to encounter fast streams, they will not persist for more than a fraction of a solar rotation. Finally, the simulations suggest that crossings of the heliospheric current sheet will persist up to approximately 70 degrees heliographic latitude.
- Publication:
-
IAU Joint Discussion
- Pub Date:
- 2000
- Bibcode:
- 2000IAUJD...7E..12R