Prevalent Small-scale Jets in the Solar Atmosphere

Recent high-resolution observations have revealed the prevalence of small-scale jet-like features in the solar atmosphere. While shaping the atmospheric dynamics, these intermittent jets also play an important role in the mass and energy supply to the corona. The characteristics of these jets have been intensively investigated through both space missions and ground-based telescopes. Some major results are summarized as follows: (1) Coronal line profiles at active region boundaries often reveal a blueward asymmetry, suggesting at least two emission components: a primary component accounting for the background emission and a secondary component associated with quasi-periodic high-speed upflows. The secondary component is caused by recurring jets with a velocity of ~50-150 km/s and is associated with propagating disturbances seen from coronal imaging observations. (2) Prevalent small-scale jets from network regions are seen in both chromospheric and TR images. Some fo them appear to be heated to coronal temperatures. At least some of these jets are found to be associated with flux emergence and/or cancellation. (3) Surge-like activity is frequently reported above light bridges, and it appears to have two components: the ever-present short and slow surges likely to be related to the upward leakage of magnetoacoustic waves, and the occasionally occurring long and fast surges caused by intermittent reconnection jets. While significantly improving our understanding of these small-scale jets, Hinode and IRIS observations have also posed new questions that need to be answered through observations from future missions such as Solar Orbiter and Solar-C.