  In the past decade, significant efforts have been made in developing
physics-based solar wind and coronal mass ejection (CME) models, which have
been or are being transferred to national centers (e.g., SWPC, CCMC) to enable
space weather predictive capability. However, the input data coverage for space
weather forecasting is extremely limited. One major limitation is the solar
magnetic field measurements, which are used to specify the inner boundary
conditions of the global magnetohydrodynamic (MHD) models. In this study, using
the Alfven wave solar model (AWSoM), we quantitatively assess the influence of
the magnetic field map input (synoptic/diachronic vs. synchronic magnetic maps)
on the global modeling of the solar wind and the CME-driven shock in the 2013
April 11 solar energetic particle (SEP) event. Our study shows that due to the
inhomogeneous background solar wind and dynamical evolution of the CME, the
CME-driven shock parameters change significantly both spatially and temporally
as the CME propagates through the heliosphere. The input magnetic map has a
great impact on the shock connectivity and shock properties in the global MHD
simulation. Therefore this study illustrates the importance of taking into
account the model uncertainty due to the imperfect magnetic field measurements
when using the model to provide space weather predictions.
