A Comparative Study of Different Approaches and Potential Improvement to Modeling the Solar Wind

The Wang-Sheeley-Arge (WSA) model is regularly used to predict the background solar wind speed and the interplanetary magnetic field (IMF) polarity from photospheric observation. The predictions near the sun are made from an empirical function which has two parameters: (1) the magnetic expansion factor and (2) the minimum angular distance from a field line foot point to the edge of the coronal hole. A kinetic propagation model is then used to determine the values at 1AU. In this paper, we address two factors can affect the result to a significant extent: (1) treatment of input data and (2) the algorithm used to compute the two parameters. We discuss the effect of synoptic chart resolution and polar field correction, and then analyze the results using three different models (potential field source surface (PFSS) model, Schatten current sheet (SCS) model integrated with PFSS, and horizontal-current current-sheet source surface (HCCSSS) model). We compare the results with observational data, and evaluate them statistically, so as to find a more physically significant scheme that works as well or better