Predicting the Optimal Poynting Flux for Different Solar Activity Conditions for Realtime Solar Wind Prediction

Its critical to have an accurate solar wind background in the inner heliosphere for space weather prediction, from the arrival of Corotating Interaction Regions (CIRs), to the Coronal Mass Ejections (CMEs), and Solar Energetic Particles (SEPs). In the space weather community, there are two major approaches to predict the solar wind background: one uses empirical or semi-empirical models, e.g., the Wang-Sheeley-Arge (WSA) model; the other is based on first-principles model, e.g., the Alfven Wave Solar atmosphere Model (AWSoM) developed at the University of Michigan. In the past, it was difficult for physics models to perform real-time solar wind predictions, because the computational cost is much higher for physics-based models than for empirical or semi-empirical models, and the optimal input parameters could be different for different solar rotations in which case the user would need to run the model with different input parameters to best predict the solar wind. Nowadays, the computational cost is not a big issue as super computers are much more powerful than before. The remaining issue is that the input parameters could vary. In real-time solar wind prediction, it is necessary to have optimal input parameters in advance. In this presentation, we study the relation between one of the most important parameters for AWSoM, the Poynting flux at the inner boundary, and the magnetic field structure of the solar corona. We obtain the optimal Poynting flux value for nine Carrington rotations in the last solar cycle and correlate it with various characteristics of the solar magnetic field, such as open flux, area of coronal holes, etc.. The preliminary results are encouraging, and suggest that the optimal parameter can be estimated from the magnetograms.