Connecting the Small Solar Wind Transients Observed Remotely to Their In Situ Measurement near 1 au

Abstract Based on the two-vantage observations by the COR2 coronagraphs on board the two STEREO spacecraft between 2010 January 1 and 2010 July 15, we reconstruct the three-dimensional (3D) structures of small solar wind transients in the extended corona and determine their velocities by using the CORrelation-Aided Reconstruction technique. From this data set, we select three small transient events that are predicted to arrive at the L1 point after extrapolating their 3D trajectories in the heliosphere. We find that the predicted trajectories are consistent with the heliospheric observations, and the transients are likely to have also been detected by in situ instruments at L1. The case 1 event is a streamer blob associated with high-density regions across the heliospheric current sheet detected 2 days before the occurrence of a stream interaction region (SIR). The case 2 transient is identified as the bright core of a streamer blowout coronal mass ejection entrained by an SIR, and the case 3 event is merged with the SIR-compressed outflow. The in situ properties related to these events and their ambient plasma flows are consistent with the properties of their source regions, identified after tracing their motion back to the solar surface. This work is an attempt to establish an exact connection between the coronal observations of a small solar wind transient and its in situ measurement at near 1 au and to understand the evolution of solar wind transients in the heliosphere.