In the realm of space weather forecasting, researchers from the Institute of Space and Astronautical Science at the Japan Aerospace Exploration Agency (JAXA) have been working on improving solar wind speed models. Kyogo Tokoro, Munehito Shoda, and Shinsuke Imada have recently proposed a novel approach to better understand and predict solar wind speeds, which can significantly impact space weather conditions and, consequently, satellite operations and power grid stability on Earth.
Solar wind speed models are crucial for space weather forecasting as they provide low computational cost predictions. One such model, known as the WS model, relies on the asymptotic expansion factor. However, this model has shown limitations, particularly in cases involving pseudostreamers. To address this, the researchers investigated the effect of the radial profile of flux-tube shape on solar wind speed using one-dimensional numerical simulations.
In their simulations, the team injected ad hoc Alfvén waves from the photosphere as an energy source and solved the magnetohydrodynamic (MHD) equations out to the interplanetary space. They found that even when the coronal base magnetic field and the asymptotic expansion factor were fixed, the final solar wind speed varied by approximately 300 km/s depending on changes in the expansion height or non-monotonic expansion. This suggests that the radial profile of the flux-tube shape plays a significant role in determining solar wind speed.
The researchers also discovered that quantities reflecting the radial profile of the flux-tube shape showed a better correlation with solar wind speed than the asymptotic expansion factor. This indicates that a more comprehensive approach, accounting for the expansion factor throughout the corona, is necessary to accurately characterize solar wind speed.
The practical applications of this research for the energy sector lie in improved space weather forecasting. Accurate predictions of solar wind speeds can help mitigate potential impacts on satellite operations, which are integral to global communication and navigation systems. Additionally, better space weather forecasts can aid in protecting power grids from geomagnetic disturbances, ensuring a more stable and reliable energy supply.
This research was published in the Astrophysical Journal, a reputable source for astrophysics and space science research. The findings contribute to the ongoing efforts to enhance our understanding of solar wind dynamics and improve space weather forecasting capabilities.
This article is based on research available at arXiv.