Characterisation of in situ signatures of coronal mass ejections interacting with high-speed streams

Interaction of Coronal Mass Ejection (CMEs) with Solar High-Speed Streams (HSSs) could alter their plasma and magnetic field properties. The properties of such an interaction should be encoded in the in-situ plasma and magnetic field observations. To characterise the properties of such interaction, we analyse the in-situ signatures of 28 interplanetary coronal mass ejections (ICMEs)b interacting with high-speed streams (HSS) at 1AU between 2010 and 2018. We analyse the ICME velocity profiles, duration of the sheath and magnetic obstacle (MO), and distortion of the MO, as well as search for the signatures of the reconnection exhausts. We find 20 events where ICME is in front of the HSS and 8 events where it is behind the HSS. Statistical analysis is performed for these two classes of interaction separately. We find that ICMEs interacting with HSS generally show distinct speed profiles for cases where HSS is in front or behind. We find that HSS catching up to ICMEs tends to accelerate them from the back, whereas HSS in front of ICMEs do not significantly alter the typical speed expansion profiles but tends to inhibit the formation of sheath. We find that 70 precent of such events does not show discernible sheath region. We find that the average magnetic field magnitude tends to be higher for cases where the ICME is in front of the HSS compared to when it is behind. Although we find reconnection exhaust signatures in about 30% events, we do not find significant evidence of the distortion of the internal magnetic structure. Our results indicate that interaction with HSS does not significantly influence the ICME internal magnetic structure, however, it may significantly influence its kinematics.