Multi-spacecraft observed magnetic clouds as seen by Helios mission

Abstract A large number of magnetic clouds (MCs) were observed during the operation period of the Helios mission. Some of the MCs were observed by multi-spacecraft, enabling a detailed study of their extension in the inner heliosphere when they pass by more than one observation location. In the present work, we analyzed 62 MCs, including 16 which were observed by multiple spacecraft and 46 observed by a single one. For those MCs observed by a single spacecraft, the cloud's axis, obtained using minimum variance analysis (MVA) on magnetic field data, could be an explanation for the fact that there were no observations at the other spacecraft. Highly inclined MCs, defined as MCs whose axes are inclined more than 45 ∘ from the ecliptic plane, are less likely to be observed by two spacecraft that are close to the ecliptic plane.