Solar Wind Modeling and Data Assimilation: Concept and First Results

Up to five simultaneously operating spacecraft monitored the solar wind in 1998-2000 between the L1 point and Earth (ACE, WIND, IMP 8, Geotail, and Interball-1). However, the current space weather prediction methods do not take advantage of these observations made at multiple points. Rather, a single upstream monitor is selected out of the available spacecraft, effectively assuming a completely uniform solar wind flow. We have initiated a project with an aim to assimilate all solar wind observations into the numerical 3D MHD model ENLIL in order to reconstruct the solar wind profile perpendicular to the Sun-Earth line. We present preliminary results of simplified model runs and discuss the benefits and difficulties of data assimilation in the solar wind.