LAUSR

Context. During the last decades great progress has been achieved in understanding the properties and the origin of the solar wind. While the sources for the fast solar wind are well understood, the sources for the slow solar wind remain elusive. Aims. The upcoming Solar Orbiter mission aims to improve our understanding of the sources of the solar wind by establishing the link between in situ and remote sensing observations. In this paper we aim to address the problem of linking in situ and remote observations in general and in particular with respect to ESA’s Solar Orbiter mission. Methods. We have used a combination of ballistic back mapping and a potential field source surface model to identify the solar wind source regions at the Sun. As an input we use in situ measurements from the Advanced Composition Explorer and magnetograms obtained from the Michelson Doppler Interferometer on board the Solar Heliospheric Observatory. For the first time we have accounted for the travel time of the solar wind above and also below the source surface. Results. We find that a prediction scheme for the pointing of any remote sensing instrumentation is required to capture a source region not only in space but also in time. An ideal remote-sensing instrument would cover up to ≈50% of all source regions at the right time. In the case of the Spectral Imaging of the Coronal Environment instrument on Solar Orbiter we find that ≈25% of all source regions would be covered. Conclusions. To successfully establish a link between in situ and remote observations the effects of the travel time of the solar wind as well as the magnetic displacement inside the corona cannot be neglected. The predictions needed cannot be based solely on a model, nor on observations alone, only the combination of both is sufficient.