The importance of boundary evolution for solar-wind modelling.

Area of Science:

• Space Physics
• Solar Physics
• Computational Astrophysics

Background:

• The solar wind, a continuous plasma outflow from the Sun's corona, influences near-Earth space weather.
• Current space weather forecasts rely on numerical fluid models constrained by photospheric magnetic field observations.
• Existing models often treat the solar wind as a steady-state flow, discarding valuable time-history information.

Purpose of the Study:

• To compare the accuracy of steady-state versus time-dependent solar wind modeling.
• To identify how steady-state assumptions impact space weather forecast reliability.
• To demonstrate the benefits of a time-dependent approach for improved forecasting.

Main Methods:

• Utilized one year of daily-updated coronal model solutions.
• Comprehensively compared steady-state (SS) solar wind modeling with a time-dependent method.
• Analyzed forecast accuracy, consistency, and heliospheric magnetic field variability.

Main Results:

• The SS approach fundamentally misrepresents the accuracy of coronal models.
• Identified three key forecasting problems linked to the SS approach: paradoxical forecast accuracy, high inconsistency in predictions, and insufficient heliospheric magnetic field variability.
• The time-dependent approach alleviates these issues, providing a more consistent and physically accurate solution.

Conclusions:

• Steady-state solar wind modeling introduces significant inaccuracies in space weather forecasting.
• A time-dependent approach, incorporating solar wind time history, offers a more reliable method for predicting conditions.
• This improved forecasting capability is crucial for mitigating the impact of space weather on technologies.