Neutral density observed (yellow), reference (red), forecast (blue), and analysis (black) for the case when all three satellite data sets were assimilated on October 29 and 30, 2003. The reference provides a benchmark for the model performance without assimilation. Forecast and analysis specifications are produced before, and after data from the current assimilation, interval have been assimilated. In this case, the reference performs poorly because of missing solar wind inputs.