A step toward data assimilation in solar wind research

Data assimilation is routinely performed for meteorological or oceanographic observations but largely unknown in heliospheric physics. Therefore, this paper will introduce basic concepts of data assimilation methods and their potential benefits to solar wind research. A data assimilation method generally employs multiple data sources and a numerical model in order to provide an accurate global description of the studied environment. This necessitates a very close cooperation between both instrumentalists and modelers because careful understanding (error analysis) of both input and simulated data is required for accurate results. As a particular example of data assimilation in heliospheric research, the paper presents a concept of a newly started project that aims to resolve the transverse solar wind profile at 1 AU from multiple solar wind monitors and the 3D solar wind numerical model ENLIL. When finished, the method will not only provide input data for magnetospheric studies but it will be also extendable to larger heliospheric scales provided that enough data sources exist.