The Origin of Extremely Non-radial Solar wind Outflows

摘要: The solar wind flow is primarily radial in nature. However, non-radial flows have been observed on several occasions, which are usually geo-effective and also have consequences on space weather. Despite that the exact origin of the non-radial flows has not yet been addressed. Here, we present our detailed investigations of 12 such non-radial events during the period 1995-2017. All the events of interest present highly non-radial solar wind cases with the azimuthal flow angle exceeding> 6 for a period of one day or more and are selected during the period when no coronal mass ejection and/or co-rotating interaction regions were seen. For most of the events, the near-Earth solar wind density was< 5 cm {-3} for periods of more than one day, similar to the well-known" solar wind disappearance events" wherein an unusual drop of the near-Earth solar wind density< 1 cm {-3} for prolonged periods (> 1 day) was …