Observations of sunward micro-jets from Parker Solar Probe

The successful Parker Solar Probe (PSP) has discovered that the solar wind in the inner heliosphere is much more active than the previous observations beyond 0.3 AU. PSP find there are lot of structures like switchbacks in the Alfvenic slow solar wind. In the slow wind observed in Encounter 8, we find quasi-periodic sunward micro-jets embedded by the slow solar wind around 250-300 km/s. These microjets have the amplitude of ~-50 km/s and the width of 10 minutes. These jets is different with the previous observations of microstreams from Ulysess and switchback jets. The jets have higher density and higher temperature, but lower magnetic field and radial solar wind velocity than the background magnetic field. However, the abundance of the alpha particles has no clear difference. The boundary of the jets have the feature of the slow shocks. We try to find the source of the microjets by trace the flows back to the solar surface.